MEDICAL: DISEASES: ZIKA VIRUS : GUIDES : DIRECTORIES : PUBLICATIONS : MEDICAL: RESOURCES: Zika Virus for Healthcare Providers FROM Centers for Disease Control and Prevention. National Center for Emerging and Zoonotic Infectious Diseases (NCEZID). Division of Vector-Borne Diseases (DVBD)

 

THIS POST CONTAINS SELECTED CONTENT FROM THE CDC WEBSITE
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MEDICAL: DISEASES: ZIKA VIRUS : 
 
GUIDES : 
 
DIRECTORIES : 
 
PUBLICATIONS : 
 
MEDICAL: RESOURCES:  
 
Zika Virus for Healthcare Providers 
 
FROM Centers for Disease Control and Prevention.   
 
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).
 
Division of Vector-Borne Diseases (DVBD)
 
 
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Back to School: Get Books Not Bites!

As your kids head back to school, teach them about Zika and how to prevent mosquito bites.

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About Zika

mosquito

What we know

  • Zika is spread mostly by the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). These mosquitoes are aggressive daytime biters. They can also bite at night.
  • Zika can be passed from a pregnant woman to her fetus. Infection during pregnancy can cause certain birth defects.
  • There is no vaccine or medicine for Zika.
  • The Florida Department of Health has identified an area in one neighborhood of Miami where Zika is being spread by mosquitoes. Learn more.

Overview

How Zika spreads

Zika can be transmitted through

Zika symptoms

most common symptoms

Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. The most common symptoms of Zika are

  • Fever
  • Rash
  • Joint pain
  • Conjunctivitis (red eyes)

Other symptoms include:

  • Muscle pain
  • Headache

Symptoms can last for several days to a week. People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. Once a person has been infected with Zika, they are likely to be protected from future infections.

Why Zika is risky for some people

Zika infection during pregnancy can cause a birth defect of the brain called microcephaly and other severe fetal brain defects. Other problems have been detected among fetuses and infants infected with Zika virus before birth, such as defects of the eye, hearing deficits, and impaired growth. There have also been increased reports of Guillain-Barré syndrome, an uncommon sickness of the nervous system, in areas affected by Zika.

How to prevent Zika

There is no vaccine to prevent Zika. The best way to prevent diseases spread by mosquitoes is to protect yourself and your family from mosquito bites. Here’s how

Treat your clothing

Clothing

  • Wear long-sleeved shirts and long pants.
  • Treat your clothing and gear with permethrin or buy pre-treated items.
using insect spray

Insect repellent

  • Use Environmental Protection Agency (EPA)-registered insect repellents with one of the following active ingredients:
    DEET, picaridin, IR3535, or oil of lemon eucalyptus or para-menthane-diol. Always follow the product label instructions.
  • When used as directed, these insect repellents are proven safe and effective even for pregnant and breastfeeding women.
  • Do not use insect repellents on babies younger than 2 months old.
  • Do not use products containing oil of lemon eucalyptus or para-menthane-diol on children younger than 3 years old.
Mosquito netting

At Home

  • Stay in places with air conditioning and window and door screens to keep mosquitoes outside.
  • Take steps to control mosquitoes inside and outside your home.
  • Mosquito netting can be used to cover babies younger than 2 months old in carriers, strollers, or cribs.
  • Sleep under a mosquito bed net if air conditioned or screened rooms are not available or if sleeping outdoors.
Using condoms or not having sex to prevent Zika

Sexual transmission

  • Prevent sexual transmission of Zika by using condoms or not having sex.

How Zika is diagnosed

  • Diagnosis of Zika is based on a person’s recent travel history, symptoms, and test results.
  • A blood or urine test can confirm a Zika infection.
  • Symptoms of Zika are similar to other illnesses spread through mosquito bites, like dengue and chikungunya.
  • Your doctor or other healthcare provider may order tests to look for several types of infections.
how to treat zika

What to do if you have Zika

There is no specific medicine or vaccine for Zika virus. Treat the symptoms:

  • Get plenty of rest.
  • Drink fluids to prevent dehydration.
  • Take medicine such as acetaminophen to reduce fever and pain.
  • Do not take aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs).
  • If you are taking medicine for another medical condition, talk to your healthcare provider before taking additional medication.

History of Zika

Zika virus was first discovered in 1947 and is named after the Zika Forest in Uganda. In 1952, the first human cases of Zika were detected and since then, outbreaks of Zika have been reported in tropical Africa, Southeast Asia, and the Pacific Islands. Zika outbreaks have probably occurred in many locations. Before 2007, at least 14 cases of Zika had been documented, although other cases were likely to have occurred and were not reported. Because the symptoms of Zika are similar to those of many other diseases, many cases may not have been recognized.

Related Resources

Zika: The Basics of the Virus and How to Protect Against It

Fact SheetsLearn more about Zika with our fact sheets and posters.

What You Need to Know

mosquitoes primarily spread

Zika primarily spreads through infected mosquitoes. You can also get Zika through sex.

Many areas in the United States have the type of mosquitoes that can spread Zika virus. These mosquitoes are aggressive daytime biters and can also bite at night. Also, Zika can be passed through sex from a person who has Zika to his or her sex partners.

prevent mosquito bites

The best way to prevent Zika is to prevent mosquito bites.

  • Use EPA-registered insect repellent. It works!
  • Wear long-sleeved shirts and long pants.
  • Stay in places with air conditioning or window and door screens.
  • Remove standing water around your home.
zika is linked to birth defects

Zika is linked to birth defects.

Zika infection during pregnancy can cause a serious birth defect called microcephaly that is a sign of incomplete brain development. Doctors have also found other problems in pregnancies and among fetuses and infants infected with Zika virus before birth. If you are pregnant and have a partner who lives in or has traveled to an area with Zika, do not have sex, or use condoms the right way, every time, during your pregnancy.

traveling

Pregnant women should not travel to areas with Zika.

If you must travel to one of these areas, talk to your healthcare provider first and strictly follow steps to prevent mosquito bites during your trip.

travelers

Returning travelers infected with Zika can spread the virus through mosquito bites.

During the first week of infection, Zika virus can be found in a person’s blood and can pass from an infected person to a mosquito through mosquito bites. An infected mosquito can then spread the virus to other people.

Couples with a partner who lives in or has traveled to an area with Zika should take steps to protect during sex.

Related Resources

Top 5 Things Everyone Needs to Know About Zika

Zika: What we know and what we don’t know

Questions About Zika

Q: What is Zika?

A: Zika virus disease is caused by the Zika virus, which is spread to people primarily through the bite of an infected mosquito (Aedes aegypti and Aedes albopictus). The illness is usually mild with symptoms lasting up to a week, and many people do not have symptoms or will have only mild symptoms. However, Zika virus infection during pregnancy can cause a serious birth defect called microcephaly and other severe brain defects.

Q: How do people get infected with Zika?

A: Zika is spread to people primarily through the bite of an infected Aedes species mosquito (Aedes aegypti and Aedes albopictus). A pregnant woman can pass Zika to her fetus during pregnancy or around the time of birth. Also, a person with Zika can pass it to his or her sex partners. We encourage people who have traveled to or live in places with Zika to protect themselves by preventing mosquito bites and sexual transmission of Zika.

Q: What health problems can result from getting Zika?

A: Many people infected with Zika will have no symptoms or mild symptoms that last several days to a week. However, Zika infection during pregnancy can cause a serious birth defect called microcephaly and other severe fetal brain defects. Current research suggests that Guillain-Barre syndrome (GBS), an uncommon sickness of the nervous system, is strongly associated with Zika; however, only a small proportion of people with recent Zika virus infection get GBS.

Once someone has been infected with Zika, it’s very likely they’ll be protected from future infections. There is no evidence that past Zika infection poses an increased risk of birth defects in future pregnancies.

Q: Should pregnant women travel to areas where Zika has been confirmed?

A: No. Pregnant women should not travel to any area with Zika. Travelers who go to places with outbreaks of Zika can be infected with Zika, and Zika infection during pregnancy can cause microcephaly and other severe fetal brain defects.

Q: If I am traveling to an area with Zika, should I be concerned about Zika?

A: Travelers who go to places with Zika can be infected with Zika, and CDC has issued travel notices for people traveling to those areas. Many people will have mild or no symptoms. However, Zika can cause microcephaly and other severe birth defects. For this reason, pregnant women should not travel to any area with Zika, and women trying to get pregnant should talk to their doctors before traveling or before their sex partners travel. It is especially important that women who wish to delay or avoid pregnancy consistently use the most effective method of birth control that they are able to use. Those traveling to areas with Zika should take steps during and after they travel to prevent mosquito bites and sexual transmission of Zika.

Q: What can people do to prevent Zika?

A: The best way to prevent Zika is to protect yourself and your family from mosquito bites:

Zika can be spread by a person infected with Zika to his or her sex partners. Condoms can reduce the chance of getting Zika from sex. Condoms include male and female condoms.  To be effective, condoms should be used from start to finish, every time during vaginal, anal, and oral sex and the sharing of sex toys. Not having sex eliminates the risk of getting Zika from sex. Pregnant couples with a partner who traveled to or lives in an area with Zika should use condoms every time they have sex or not have sex during the pregnancy.

Q: What are the symptoms of Zika virus disease?

A: The most common symptoms of Zika virus disease are fever, rash, joint pain, and red eyes. Other symptoms include muscle pain and headache. Many people infected with Zika won’t have symptoms or will have mild symptoms, which can last for several days to a week.

Q: How is Zika diagnosed?

A: To diagnose Zika, your doctor will ask you about recent travel and symptoms you may have, and collect blood or urine to test for Zika or similar viruses.

Q: Can someone who returned from an area with Zika get tested for the virus?

A: Zika virus testing is performed at CDC and some state and territorial health departments. See your doctor if you have Zika symptoms and have recentlybeen in an area with Zika. Your doctor may order tests to look for Zika or similar viruses like dengue and chikungunya.

Q:What should pregnant women who have recently traveled to an area with Zika do?

A: Pregnant women who have recently traveled to an area with Zika should talk to their doctor about their travel, even if they don’t feel sick. Pregnant women should see a doctor if they have any Zika symptoms during their trip or within 2 weeks after traveling. All pregnant women can protect themselves by avoiding travel to an area with Zika, preventing mosquito bites, and following recommended precautions against getting Zika through sex.

Prevention

A husband and wife with their two children

What we know

  • No vaccine exists to prevent Zika.
  • Prevent Zika by avoiding mosquito bites.
  • Mosquitoes that spread Zika virus bite during the day and night.
  • Mosquitoes that spread Zika virus also spread dengue and chikungunya viruses.
  • Zika can be passed through sex from a person who has Zika to his or her sex partners. Condoms can reduce the chance of getting Zika from sex. Condoms include male and female condoms.
  • Local mosquito-borne Zika virus transmission has been reported in two areas of Miami. Learn more.

What you can do to protect yourself and others

  • PROTECT YOURSELF & OTHERS

    Prevent mosquito bites, plan for travel, protect during sex and more.

  • PREVENT MOSQUITO BITES

    The best way to prevent Zika is to protect yourself from mosquito bites.

  • PLAN FOR TRAVEL

    Learn what to do before, during, and after your trip to protect yourself and others.

  • PROTECT YOURSELF DURING SEX

    Learn how to prevent sexual transmission of Zika, especially if you or your partner is pregnant.

  • PROTECT YOURSELF & OTHERS

    Prevent mosquito bites, plan for travel, protect during sex and more.

  • PREVENT MOSQUITO BITES

    The best way to prevent Zika is to protect yourself from mosquito bites.

  • PLAN FOR TRAVEL

    Learn what to do before, during, and after your trip to protect yourself and others.

  • PROTECT YOURSELF DURING SEX

    Learn how to prevent sexual transmission of Zika, especially if you or your partner is pregnant.

Protect Yourself & Others

a husband with his hand on his pregnant wife's stomach

Use the tips below to protect yourself & others from Zika

  • Following these tips will help to protect you, your partner, your family, your friends, and your community from Zika. The more steps you take, the more protected you are.

a bottle of insect repellent

Prevent mosquito bites

  • Zika virus is spread to people mainly through the bite of an infected mosquito.
  • Mosquitoes that spread Zika virus bite mostly during the day, but they can also bite at night.
  • The best way to prevent Zika is to protect yourself from mosquito bites.

What you can do

Build a Zika Prevention Kit

Be prepared

If you live in a state or area with the mosquito that spreads the Zika virus and are concerned about Zika, build your own Zika Prevention Kit with the items below. Reducing the risk for Zika is particularly important for pregnant women.

Your kit should include:

a bed net used to cover your sleeping area

Bed net

  • Keep mosquitoes out of your room, day and night. If your room is not well screened, use a bed net when sleeping or resting.
  • Mosquitoes can live indoors and will bite at any time, day or night.

a package of standing water treatment tabs

Standing water treatment tabs

  • Use water treatment tabs to kill larvae in standing water around your house. Do not put them in water you drink.
  • Always follow directions on the package.
  • When used as directed, these tabs will not harm you or your pets (dogs and cats).

a bottle of insect repellent

Insect repellent

  • Insect repellent will help keep mosquitoes from biting you.
  • Always follow directions on the package.
  • Use only an EPA-registered insect repellent.
  • Do not spray repellent on the skin under clothing.
  • If you are also using sunscreen, apply sunscreen first and insect repellent second.
  • When used as directed, these insect repellents are proven safe and effective even for pregnant and breastfeeding women.
  • Learn how to prevent mosquito bites.

a can of permethrin spray

Permethrin spray

  • Spray your clothing and gear with permethrin to help protect yourself from mosquito bites.
  • Always follow the directions on the bottle. Reapply as directed.
  • Do not spray permethrin on your skin.

a box of condoms

Condom

  • During sex, it is possible to get Zika virus from a person who has Zika.
  • If you have sex (vaginal, anal, or oral) with a partner who may have been exposed to Zika, you should use condoms the right way every time.
  • Follow directions on the box.
  • Condoms can also help prevent HIV and other sexually transmitted diseases.
  • Learn how to protect during sex and use condoms correctly. See Condom Dos and Don’ts. English[PDF – 2 pages] Spanish[PDF – 2 pages]

Build Your Own Zika Prevention Kit

Zika Prevention Kit for Pregnant Women flyer thumbnail

Build Your Own Zika Prevention Kit

Zika Prevention Kit Materials

Zika Prevention Kit Material List
Pregnant and Living in an Area with Zika?
Pregnant? Protect Yourself from Mosquito Bites
Condom Use Palm Card
Larvicide Dunk Use Wallet Cards
Bed Net Use Wallet Cards

Prevent Mosquito Bites

Protect yourself and your family from mosquito bites

a human hand pointing to the instructions on a can of insect repellent

Use Insect Repellent

Use Environmental Protection Agency (EPA)-registered insect repellents with one of the active ingredients below. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women.

A chart showing examples of insect repellents broken down by active ingredients and product brands that contain those ingredients.  The first active ingredient listed is DEET. Some examples of brand name products containing DEET are OFF, Cutter, Sawyer, and Ultrathon. The second active ingredient listed is Picaridin, also know as KBR 3023, Bayrepel, and icardin. Some examples of brand name products containing Picaridin are Cutter Advanced, Skin So Soft Bug Guard Plus, and Autan, which is found outside the United States. The third active ingredient listed is Oil of lemon eucalyptus or para-menthane-diol. An example of a brand name product containing Oil of lemon eucalyptus is Repel. The fourth and final active ingredient listed is IR3535.  Some examples of brand name products containing IR3535 are Skin So Soft Bug Guard Plus Expedition and SkinSmart.* Insect repellent brand names are provided for your information only. The Centers for Disease Control and Prevention and the U.S. Department of Health and Human Services cannot recommend or endorse any name brand products.

Tips for Everyone

  • Always follow the product label instructions.
  • Reapply insect repellent as directed.
    • Do not spray repellent on the skin under clothing.
    • If you are also using sunscreen, apply sunscreen first and insect repellent second.

Tips for Babies & Children

an adult male applying insect repellent to a child's face

  • Always follow instructions when applying insect repellent to children.
  • Do not use insect repellent on babies younger than 2 months old.
  • Do not apply insect repellent onto a child’s hands, eyes, mouth, and cut or irritated skin.
    • Adults: Spray insect repellent onto your hands and then apply to a child’s face.
  • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.

Natural insect repellents (repellents not registered with EPA)

  • We do not know the effectiveness of non-EPA registered insect repellents, including some natural repellents.
  • To protect yourself against diseases like chikungunya, dengue, and Zika, CDC and EPA recommend using an EPA-registered insect repellent.
  • Choosing an EPA-registered repellent ensures the EPA has evaluated the product for effectiveness.
  • Visit the EPA website to learn more.

a babies crib covered by a mosquito net

Protect your baby or child

  • Dress your child in clothing that covers arms and legs.
  • Cover crib, stroller, and baby carrier with mosquito netting.

a bottle of insect repellent shown spraying clothing

Wear long-sleeved shirts and long pants

  • Treat items, such as boots, pants, socks, and tents, with permethrin or buy permethrin-treated clothing and gear.
    • Permethrin-treated clothing will protect you after multiple washings. See product information to find out how long the protection will last.
    • If treating items yourself, follow the product instructions.
    • Do not use permethrin products directly on skin.

a mosquito protected house

Take steps to control mosquitoes inside and outside your home

  • Use screens on windows and doors. Repair holes in screens to keep mosquitoes outside.
  • Use air conditioning when available.
    • Sleep under a mosquito bed net if air conditioned or screened rooms are not available or if sleeping outdoors.
  • Once a week, empty and scrub, turn over, cover, or throw out items that hold water, such as tires, buckets, planters, toys, pools, birdbaths, flowerpots, or trash containers. Check inside and outside your home. Mosquitoes lay eggs near water.

Controlling Mosquitoes at Home

illustration of a woman pouring water from a bucket

Control mosquitoes outside your home

Remove standing water where mosquitoes could lay eggs

  • Once a week, empty and scrub, turn over, cover, or throw out any items that hold water like tires, buckets, planters, toys, pools, birdbaths, flowerpot saucers, or trash containers. Mosquitoes lay eggs near water.
  • Tightly cover water storage containers (buckets, cisterns, rain barrels) so that mosquitoes cannot get inside to lay eggs.
  • For containers without lids, use wire mesh with holes smaller than an adult mosquito.
  • Use larvicides to treat large containers of water that will not be used for drinking and cannot be covered or dumped out.
  • If you have a septic tank, repair cracks or gaps. Cover open vent or plumbing pipes. Use wire mesh with holes smaller than an adult mosquito.

Kill mosquitoes outside your home

  • Use an outdoor insect spray made to kill mosquitoes in areas where they rest.
  • Mosquitoes rest in dark, humid areas like under patio furniture, or under the carport or garage. When using insecticides, always follow label instructions.
illustration of a mosquito that has been crossed out with a red mark

Control mosquitoes inside your home

Keep mosquitoes out

  • Install or repair and use window and door screens. Do not leave doors propped open.
  • Use air conditioning when possible.

Remove standing water where mosquitoes could lay eggs

  • Once a week, empty and scrub, turn over, cover, or throw out any items that hold water like vases and flowerpot saucers. Mosquitoes lay eggs near water.

Kill mosquitoes inside your home

  • Kill mosquitoes inside your home. Use an indoor insect fogger* or indoor insect spray* to kill mosquitoes and treat areas where they rest. These products work immediately, and may need to be reapplied. When using insecticides, always follow label directions. Only using insecticide will not keep your home free of mosquitoes.
  • Mosquitoes rest in dark, humid places like under the sink, in closets, under furniture, or in the laundry room.
Product Active ingredient Brand name examples** How long it works
Indoor insect spray Imidacloprid, β-Cyfluthrin Home Pest Instect Killer, Raid Ortho, HotShot, EcoLogic 7-10 days
Indoor insect spray Tetramethrin, Cypermethrin HotShot, Raid, Real Kil, Spectracide Up to 6 weeks

**Insecticide brand names are provided for your information only. CDC and the U.S. Department of Health and Human Services cannot recommend or endorse any name brand products.

Plan for Travel

Before your trip

a pregnant woman standing in front of a world globe

If you are pregnant or trying to get pregnant

During your trip

a bottle of insect repellent

Protect yourself from mosquito bites

a bed net product

Keep mosquitoes outside

  • Stay in places with air conditioning and with window/door screens.
  • Use a bed net if air conditioned or screened rooms are not available or if sleeping outdoors.

After your trip

illustration of a mosquito that is crossed out with a red mark

Protect yourself from mosquito bites

  • Even if you do not feel sick, travelers returning to the United States from an area with Zika should take steps to prevent mosquito bites for 3 weeks so they do not spread Zika to mosquitoes that could spread the virus to other people.

a pregnant couple pictured next to a box of condoms

Protect yourself during sex

  • Protect yourself during sex, especially if your partner traveled to an area with Zika or if you are pregnant or considering getting pregnant.
  • The amount of time you need to protect yourself during sex depends on whether your partner has symptoms and whether you are pregnant or trying to get pregnant. For specific guidelines, see protect yourself during sex.

illustration of a doctor holding a clipboard

See a doctor or healthcare professional

Transmission & Risks

Through mosquito bites

Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (Ae. aegypti and Ae. albopictus). These are the same mosquitoes that spread dengue and chikungunyaviruses.

  • These mosquitoes typically lay eggs in and near standing water in things like buckets, bowls, animal dishes, flower pots and vases.  They prefer to bite people, and live indoors and outdoors near people.
    • Mosquitoes that spread chikungunya, dengue, and Zika are aggressive daytime biters, but they can also bite at night.
  • Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites.

From mother to child

  • A pregnant woman can pass Zika virus to her fetus during pregnancy. Zika is a cause of microcephaly and other severe fetal brain defects. We are studying the full range of other potential health problems that Zika virus infection during pregnancy may cause.
  • A pregnant woman already infected with Zika virus can pass the virus to her fetus during the pregnancy or around the time of birth.
  • To date, there are no reports of infants getting Zika virus through breastfeeding. Because of the benefits of breastfeeding, mothers are encouraged to breastfeed even in areas where Zika virus is found.

Through sex

  • Zika can be passed through sex from a person who has Zika to his or her partners. Zika can be passed through sex, even if the infected person does not have symptoms at the time.
    • It can be passed from a person with Zika before their symptoms start, while they have symptoms, and after their symptoms end.
    • Though not well documented, the virus may also be passed by a person who carries the virus but never develops symptoms.
  • Studies are underway to find out how long Zika stays in the semen and vaginal fluids of people who have Zika, and how long it can be passed to sex partners. We know that Zika can remain in semen longer than in other body fluids, including vaginal fluids, urine, and blood.

Through blood transfusion

  • To date, there have not been any confirmed blood transfusion transmission cases in the United States.
  • There have been multiple reports of blood transfusion transmission cases in Brazil. These reports are currently being investigated.
  • During the French Polynesian outbreak, 2.8% of blood donors tested positive for Zika and in previous outbreaks, the virus has been found in blood donors.

Through laboratory exposure

  • Prior to the current outbreak, there were four reports of laboratory acquired Zika virus infections, although the route of transmission was not clearly established in all cases.
  • As of June 15, 2016, there has been one reported case of laboratory-acquired Zika virus disease in the United States.

Risks

  • Anyone who lives in or travels to an area where Zika virus is found and has not already been infected with Zika virus can get it from mosquito bites. Once a person has been infected, he or she is likely to be protected from future infections.

Zika and Sexual Transmission

Basics of Zika Virus and Sex

Transmission

  • Zika can be passed through sex from a person who has Zika to his or her sex partners.
  • Sex includes vaginal, anal, oral sex, and the sharing of sex toys.
  • Zika can be passed through sex, even if the person does not have symptoms at the time.
    • It can be passed from a person with Zika before their symptoms start, while they have symptoms, and after their symptoms end.
    • Though not well documented, the virus may also be passed by a person who carries the virus but never develops symptoms.
  • Studies are underway to find out how long Zika stays in the semen and vaginal fluids of people who have Zika, and how long it can be passed to sex partners. We know that Zika can remain in semen longer than in other body fluids, including vaginal fluids, urine, and blood.

Prevention Basics

  • Condoms can reduce the chance of getting Zika from sex.
    • Condoms include male and female condoms.
    • Dental dams (latex or polyurethane sheets) may also be used for certain types of oral sex (mouth to vagina or mouth to anus).
  • To be effective, condoms should be used from start to finish, every time during vaginal, anal, and oral sex.
  • Not sharing sex toys can also reduce the risk of spreading Zika to sex partners.
  • Not having sex eliminates the risk of getting Zika from sex.

What CDC is Doing

CDC and other public health partners continue to study Zika virus and how it is spread and will share new information as it becomes available. This continuing research may help us find out:

  • How common it is for Zika to be passed during sex by a man or woman.
  • If Zika can be passed through saliva during deep kissing.
  • If Zika passed to a pregnant woman during sex has a different risk for birth defects than Zika transmitted by a mosquito bite.

How to Prevent Sexual Transmission of Zika

Pregnant Couples collapsed

Couples Considering Pregnancy collapsed

Others Concerned About the Sexual Transmission of Zika collapsed

Sexual Transmission and Testing

  • Pregnant women with possible sexual exposure to Zika should be tested for Zika infection.
  • CDC recommends Zika virus testing for people who may have been exposed to Zika through sex and who have Zika symptoms.
  • Testing blood, semen, vaginal fluids, or urine is not recommended to determine how likely a person is to pass Zika virus through sex. This is because there is still a lot we don’t know about the virus and how to interpret test results. Available tests may not accurately identify the presence of Zika or a person’s risk of passing it on through sex.
  • As we learn more and as tests improve, these tests may become more helpful for determining a person’s risk of passing Zika through sex.

Additional Resources

Zika and Sex: Information for men who have pregnant partners and live in or recently traveled to areas with Zika

Zika and Sex: Information for pregnant women living in areas with Zika

Pregnant and living in an area with Zika?

Pregnant? Read this before you travel

Zika and sexual transmission - What we know and what we dont know factsheet thumbnail

Basics of Zika virus and sex

How to Protect Yourself from Getting Zika from Sex Information for People whose Partner Traveled to an Area with Zika factsheet thumbnail

Zika and Sexual Transmission: For People Whose Partner Traveled to an Area with Zika

How to Protect yourself from getting zika from Sex Information for people living in areas with zika fact sheet thumbnail

Zika and Sexual Transmission: For People Living in an Area with Zika

Zika and Blood Transfusion

  • BLOOD AND TISSUE COLLECTION CENTERS

  • AREAS AT RISK

What we know

  • Zika virus currently poses a low risk to the blood supply in the continental US, but this could change depending on how many people become infected with the virus.
  • There is a strong possibility that Zika virus can be spread through blood transfusions.
    • Because most people infected with the Zika virus don’t show any symptoms, blood donors may not know they have been infected.
    • There have been cases of Zika transmission through blood transfusion in Brazil. During the previous French Polynesian Zika virus outbreak, 2.8% of blood donors tested positive for Zika and in previous outbreaks, the virus has been found in blood donors.
  • On August 26, 2016, the US Food and Drug Administration (FDA) issued revised guidance to prevent the spread of Zika virus through the blood supply. This new FDA guidance calls for blood collection centers in the United States to screen all donated blood for Zika virus.

Zika Virus Blood Screening

  • Blood donor screening on the basis of a questionnaire, without a laboratory test, is insufficient for identifying Zika-infected donors in areas with active mosquito-borne transmission of Zika virus due to the high rate of asymptomatic infection.
  • Although there is no FDA-licensed test for Zika virus, testing for Zika became available through two separate Investigational New Drug (IND) applications for blood collected in Puerto Rico and mainland United States.  The tests became available on April 3, 2016 (Roche Molecular Systems, Inc.) and June 20, 2016 (Hologic, Inc./Grifols).
    • Puerto Rico began using the Roche IND on April 3, 2016
    • Texas, Florida, Alabama, Mississippi, Georgia, and South Carolina are currently using one of the two INDs.
    • Additional locations in the US are expected to implement testing in the coming months.
  • Blood donations that test positive for Zika virus are removed from the blood supply.

For Blood Collection Centers and Health Departments

One of the most important aspects of blood safety is making sure donated blood does not cause harm. One way CDC plays an important role in keeping the blood supply safe is by assisting state and local health departments and hospitals in investigating reports of potential infectious disease transmission. CDC developed an Investigation Toolkit: Transfusion-Transmitted Infections (TTI) as a resource to facilitate investigating and tracking potential transfusion-associated cases of infection (e.g., by public health departments). The toolkit provides a broadly applicable framework for transfusion investigations.

Zika and Animals

What we know

a female Aedes aegypti mosquito as she was obtaining a blood-meal from a human host through her fascicle

Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito (A. aegypti and A. albopictus). These are the same mosquitoes that spread dengue andchikungunya viruses. At this time there have been no reports of other animals becoming sick with Zika or of being able to spread Zika to people or other animals.

  • At this time, animals do not appear to be involved in the spread of Zika virus.
  • There is no evidence that Zika virus is spread to people from contact with animals.
  • There have not been any reports of pets or other types of animals becoming sick with Zika virus. However, more research is needed to better understand Zika virus in animals.

Zika in animals

Zika virus was first discovered in a monkey with a mild fever in the Zika Forest of Uganda in the 1940s. Nonhuman primates (apes and monkeys) have shown the ability to become infected with Zika virus; but, only a few naturally and experimentally infected monkeys and apes have had any signs of illness at all, and then it was only a mild, transient fever without any other symptoms. A small number of monkeys were reported to have Zika virus in one study done in 2016 in an area of Brazil with high numbers of human illness. More research is needed to better understand the potential for monkeys and apes to be reservoirs for Zika virus. The prevalence of Zika virus in monkeys and other nonhuman primates is currently unknown.

There is also limited evidence from one study done in Indonesia in the late 1970s that horses, cows, carabaos (water buffaloes), goats, ducks, and bats could become infected with Zika, but there is no evidence that they develop disease or pose a risk for Zika virus transmission to humans. There have not been any reports of pets or other types of animals becoming sick with Zika virus. More information on Zika virus transmission is available here.

Zika and microcephaly in animal pregnancy

Microcephaly has not been reported among populations of monkeys and apes in areas with previous or ongoing Zika virus transmission. This type of birth defect has not been reported with Zika virus infection in animals living in areas where Zika virus is present. However, more research is needed to better understand Zika virus and microcephaly in animal pregnancy.

golden retriever lying in the grass

Risk to monkeys and apes in the United States

The risk of monkeys and apes in the United States becoming infected with Zika virus is low. All monkeys and apes imported into the United States undergo a mandatory 31-day quarantine period on arrival.

  • The monkeys and apes are held indoors or in screened enclosures where the risk of mosquito contact is low.
  • Any monkey or ape that may have entered quarantine with an active Zika virus infection would not be able to pass it to others without mosquitoes.
  • Monkeys and apes develop antibodies to Zika virus within 14 days of infection; once antibodies develop, a person or primate can no longer spread the virus. All imported monkeys and apes should be free of Zika virus by the end of the quarantine period and thus pose no risk of infecting local mosquito populations

Bringing pets or other animals into the United States

Some animals, including monkeys and apes, are not allowed to be imported as pets under any circumstances. Each state and US territory has its own rules for pet ownership and importation, and these rules may be different from federal regulations. You can find more information about animal importation here.

Symptoms, Testing, & Treatment

Diagnosis

What we know

  • Many people infected with Zika virus won’t have symptoms or will only have mild symptoms.
  • A blood or urine test can confirm Zika infection diagnosis.
  • There is no specific medicine for Zika.

Symptoms

Zika Virus Symptoms

Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. The most common symptoms of Zika are

  • Fever
  • Rash
  • Joint pain
  • Conjunctivitis (red eyes)

Other symptoms include:

  • Muscle pain
  • Headache

How long symptoms last

Zika is usually mild with symptoms lasting for several days to a week. People usually don’t get sick enough to go to the hospital, and they very rarely die of Zika. For this reason, many people might not realize they have been infected. Symptoms of Zika are similar to other viruses spread through mosquito bites, like dengue and chikungunya.

How soon you should be tested

Zika virus usually remains in the blood of an infected person for about a week. See your doctor or other healthcare provider if you develop symptoms and you live in or have recently traveled to an area with Zika. Your doctor or other healthcare provider may order blood tests to look for Zika or other similar viruses like dengue or chikungunya. Once a person has been infected, he or she is likely to be protected from future infections.

When to see a doctor or healthcare provider

See your doctor or other healthcare provider if you have the symptoms described above and have visited an area with Zika, this is especially important if you are pregnant.  Be sure to tell your doctor or other healthcare provider where you traveled.

If you think you have Zika

Related Resources

Doctor’s Visit Checklist: For Pregnant Women Who Traveled to an Area with Zika

Doctor’s Visit Checklist: For Pregnant Women Living in an Area with Zika

Testing for Zika

Diagnosis

Diagnosis

  • Diagnosis of Zika is based on a person’s recent travel history, symptoms, and test results.
  • A blood or urine test can confirm a Zika infection.
  • Your doctor or other healthcare provider may order blood tests to look for Zika or other similar viruses like dengue or chikungunya.

Sexual Transmission and Testing

  • CDC recommends Zika virus testing for people who may have been exposed to Zika through sex and who have Zika symptoms.
  • A pregnant woman with possible exposure to Zika virus from sex should be tested. Possible exposure to Zika virus from sex includes sex without a barrier to protect against infection with a partner who traveled to or lives in an area with Zika.
  • Testing blood, semen, vaginal fluids, or urine is not recommended to determine how likely a person is to pass Zika virus through sex. This is because there is still a lot we don’t know about the virus and how to interpret test results. Available tests may not accurately identify the presence of Zika or a person’s risk of passing it on.
  • As we learn more and as tests improve, these tests may become more helpful for determining a person’s risk of passing Zika through sex.

If you think you may have or had Zika

Related Resources

For Nonpregnant Women: A Positive Zika Virus Test: What does it mean for me?

For Pregnant Women: A Positive Zika Virus Test: What does it mean for me?

For Men: A Positive Zika Virus Test: What does it mean for me?

For Parents: A Positive Zika Virus Test: What does it mean for my child?

What happens when I am tested for Zika and when will I get my results?

Fact SheetsLearn more about Zika with our fact sheets and posters.

Treatment

Treatment

There is no specific medicine or vaccine for Zika virus.

  • Treat the symptoms.
  • Get plenty of rest.
  • Drink fluids to prevent dehydration.
  • Take medicine such as acetaminophen (Tylenol®) or paracetamol to reduce fever and pain.
  • Do not take aspirin and other non-steroidal anti-inflammatory drugs (NSAIDS) until dengue can be ruled out to reduce the risk of bleeding.
  • If you are taking medicine for another medical condition, talk to your healthcare provider before taking additional medication.

If you think you may have or had Zika

Tell your doctor or healthcare provider and take these steps to protect others.

Areas with Zika

Key Facts

Blood and Tissue Collection Community

Areas of active transmission for blood and tissue safety intervention

More

Local mosquito-borne transmission

Local mosquito populations infected with Zika virus can transmit it to humans. “What is Local Transmission?”  [PDF – 1 page]

Travel-associated transmission (imported case)

Infection associated with travel to an area with local mosquito-borne transmission.

See “What is an imported case?”[PDF – 1 page]

All Countries & Territories with Active Zika Virus Transmission

Americas
  • Anguilla
  • Antigua and Barbuda
  • Argentina
  • Aruba
  • The Bahamas
  • Barbados
  • Belize
  • Bolivia
  • Bonaire
  • Brazil
  • British Virgin Islands
  • Cayman Islands
  • Colombia
  • Commonwealth of
    Puerto Rico, US territory
  • Costa Rica
  • Cuba
  • Curacao
  • Dominica
  • Dominican Republic
  • Ecuador
  • El Salvador
  • French Guiana
  • Grenada
  • Guadeloupe
  • Guatemala
  • Guyana
  • Haiti
  • Honduras
  • Jamaica
  • Martinique
  • Mexico
  • Nicaragua
  • Panama
  • Paraguay
  • Peru
  • Saba
  • Saint Barthélemy
  • Saint Lucia
  • Saint Martin
  • Saint Vincent and the Grenadines
  • Sint Eustatius
  • Sint Maarten
  • Suriname
  • Trinidad and Tobago
  • Turks and Caicos
  • United States
  • U.S. Virgin Islands
  • Venezuela
Oceania/Pacific Islands
  • American Samoa
  • Fiji
  • Kosrae, Federated States of Micronesia
  • Marshall Islands
  • New Caledonia
  • Papua New Guinea
  • Samoa
  • Tonga
Africa
  • Cape Verde
Asia
  • Singapore

Case Counts in the US

As of August 31, 2016 (5 am EST)

  • Zika virus disease and Zika virus congenital infection are nationally notifiable conditions.
  • This update from the CDC Arboviral Disease Branch includes provisional data reported to ArboNET for January 01, 2015 – August 31, 2016.

US States

  • Locally acquired mosquito-borne cases reported: 35
  • Travel-associated cases reported: 2,686
  • Laboratory acquired cases reported:  1
  • Total: 2,722
    • Sexually transmitted: 23
    • Guillain-Barré syndrome: 7

MAPS OF ZIKA IN THE US

US Territories

  • Locally acquired cases reported: 14,059
  • Travel-associated cases reported: 51
  • Total: 14,110*
    • Guillain-Barré syndrome: 32

*Sexually transmitted cases are not reported for US territories because with local transmission of Zika virus it is not possible to determine whether infection occurred due to mosquito-borne or sexual transmission.

Laboratory-confirmed Zika virus disease cases reported to ArboNET by state or territory — United States, 2015–2016 (as of August 31, 2016)§

States Travel-associated cases*
No. (% of cases in states)
(N=2,687)
Locally acquired cases†
No. (% of cases in states)
(N=35)
Alabama 24    (1) 0    (0)
Arizona 20    (1) 0    (0)
Arkansas 9      (<1) 0    (0)
California 152  (6) 0    (0)
Colorado 27    (1) 0    (0)
Connecticut 52    (2) 0    (0)
Delaware 11    (<1) 0    (0)
District of Columbia 11    (<1) 0    (0)
Florida 507  (19) 35    (100)
Georgia 69    (3) 0    (0)
Hawaii 11    (<1) 0    (0)
Idaho 2      (<1) 0    (0)
Illinois 51    (2) 0    (0)
Indiana 31    (1) 0    (0)
Iowa 14    (1) 0    (0)
Kansas 13    (<1) 0    (0)
Kentucky 20    (1) 0    (0)
Louisiana 26    (1) 0    (0)
Maine 11    (<1) 0    (0)
Maryland 85    (3) 0    (0)
Massachusetts 65    (2) 0    (0)
Michigan 43    (2) 0    (0)
Minnesota 40    (1) 0    (0)
Mississippi 18    (1) 0    (0)
Missouri 23    (1) 0    (0)
Montana 7      (<1) 0    (0)
Nebraska 8      (<1) 0    (0)
Nevada 13    (<1) 0    (0)
New Hampshire 8      (<1) 0    (0)
New Jersey 91    (3) 0    (0)
New Mexico 3      (<1) 0    (0)
New York 625  (23) 0    (0)
North Carolina 48    (2) 0    (0)
North Dakota 1      (<1) 0    (0)
Ohio 33    (1) 0    (0)
Oklahoma 20    (1) 0    (0)
Oregon 19    (1) 0    (0)
Pennsylvania†† 90    (3) 0    (0)
Rhode Island 28    (1) 0    (0)
South Carolina 31    (1) 0    (0)
South Dakota 1      (<1) 0    (0)
Tennessee 37    (1) 0    (0)
Texas 136  (5) 0    (0)
Utah 10    (<1) 0    (0)
Vermont 7      (<1) 0    (0)
Virginia 75    (3) 0    (0)
Washington 26    (1) 0    (0)
West Virginia 11    (<1) 0    (0)
Wisconsin 24    (1) 0    (0)
Territories Travel-associated cases*
No. (% of cases in territories)
(N=51)
Locally acquired cases†
No. (% of cases in territories)
(N=14,059)
American Samoa 0      (0) 47         (<1)
Puerto Rico 50    (98) 13,791**  (98)
US Virgin Islands 1      (2) 221       (2)

§Only includes cases meeting the probable or confirmed CSTE case definition and does not include asymptomatic infections unless the case is a pregnant woman with a complication of pregnancy
*Travelers returning from affected areas, their sexual contacts, or infants infected in utero
†Presumed local mosquito-borne transmission
††One additional case acquired through laboratory transmission
**During the week of August 24–31, 2016, the Puerto Rico Department of Health retroactively reported approximately 5,000 cases identified from June 4–August 6, 2016, resulting in a larger than normal increase in cases over prior weeks.

Pregnant Women with Any Laboratory Evidence of Possible Zika Virus Infection in the United States and Territories, 2016

Pregnant Women with Any Laboratory Evidence of Possible Zika Virus Infection

US States and the District of Columbia*

624

*Includes aggregated data reported to the US Zika Pregnancy Registry as of August 25, 2016

US Territories**

971

**Includes aggregated data from the US territories reported to the US Zika Pregnancy Registry and data from Puerto Rico reported to the Zika Active Pregnancy Surveillance System as of August 25, 2016

About These Numbers

What these updated numbers show

  • These numbers reflect the number of pregnancies with laboratory evidence of possible Zika virus infection that have been reported to the pregnancy surveillance systems. There are some delays in reporting.  The latest numbers on the total number of pregnant women with Zika are typically available on the individual websites for each jurisdiction.  In addition, reported numbers may increase or decrease as preliminary information is clarified.
  • This information will help healthcare providers as they counsel pregnant women affected by Zika and is essential for planning at the federal, state, and local levels for clinical, public health, and other services needed to support pregnant women and families affected by Zika.

What these new numbers do not show

  • These new numbers are not comparable to the previous reports. These updated numbers reflect a different, broader population of pregnant women.
  • These updated numbers are not real time estimates. They will reflect the number of pregnant women reported with any laboratory evidence of possible Zika virus infection as of 12 noon every Thursday the week prior; numbers will be delayed one week.

Where do these numbers come from?

These data reflect pregnant women in the US Zika Pregnancy Registry and the Zika Active Pregnancy Surveillance System in Puerto Rico. CDC, in collaboration with state, local, tribal and territorial health departments, established these registries for comprehensive monitoring of pregnancy and infant outcomes following Zika virus infection.

The data collected through these registries will be used to update recommendations for clinical care, to plan for services and support for pregnant women and families affected by Zika virus, and to improve prevention of Zika virus infection during pregnancy.

What are the outcomes for these pregnancies?

Visit CDC’s webpage for updated counts of poor pregnancy outcomes related to Zika. Most of the pregnancies monitored by these systems are ongoing. CDC will not report outcomes until pregnancies are complete.

Outcomes of Pregnancies with Laboratory Evidence of Possible Zika Virus Infection in the United States, 2016

Pregnancy Outcomes in the United States and the District of Columbia

Liveborn infants with birth defects*

16

Includes aggregated data reported to the US Zika Pregnancy Registry as of August 25, 2016

Pregnancy losses with birth defects**

5

Includes aggregated data reported to the US Zika Pregnancy Registry as of August 25, 2016

Pregnancy Outcomes in the United States Territories

Liveborn infants with birth defects*

1

Includes aggregated data from the US territories reported to the US Zika Pregnancy Registry and data from Puerto Rico reported to the Zika Active Pregnancy Surveillance System as of August 25, 2016

Pregnancy losses with birth defects**

1

Includes aggregated data from the US territories reported to the US Zika Pregnancy Registry and data from Puerto Rico reported to the Zika Active Pregnancy Surveillance System as of August 25, 2016

What these numbers show
  • These numbers reflect the number of poor outcomes among pregnancies with laboratory evidence of possible Zika virus infection that have been reported to the pregnancy surveillance systems. There are some delays in reporting.  The latest numbers on the total number of pregnant women with Zika are typically available on the individual websites for each jurisdiction.  In addition, reported numbers may increase or decrease as preliminary information is clarified.
  • The number of live-born infants and pregnancy losses with birth defects are combined for the 50 US states, the District of Columbia, and the US territories. To protect the privacy of the women and children affected by Zika, CDC is not reporting individual state, tribal, territorial or jurisdictional level data.
  • The poor birth outcomes reported include those that have been detected in infants infected with Zika before or during birth, including microcephaly, calcium deposits in the brain indicating possible brain damage, excess fluid in the brain cavities and surrounding the brain, absent or poorly formed brain structures, abnormal eye development, or other problems resulting from damage to brain that affects nerves, muscles and bones, such as clubfoot or inflexible joints, and confirmed hearing loss.

What these new numbers do not show

  • These numbers are not real time estimates. They will reflect the outcomes of pregnancies reported with any laboratory evidence of possible Zika virus infection as of 12 noon every Thursday the week prior; numbers will be delayed one week.
  • These numbers do not reflect outcomes among ongoing pregnancies.
  • Although these outcomes occurred in pregnancies with laboratory evidence of Zika virus infection, we do not know whether they were caused by Zika virus infection or other factors.

Where do these numbers come from?

  • These data reflect pregnancies reported to the US Zika Pregnancy Registry and the Zika Active Pregnancy Surveillance System. CDC, in collaboration with state, local, tribal and territorial health departments, established these systems for comprehensive monitoring of pregnancy and infant outcomes following Zika virus infection.
  • The data collected through these systems will be used to update recommendations for clinical care, to plan for services and support for pregnant women and families affected by Zika virus, and to improve prevention of Zika virus infection during pregnancy.

These registries are covered by an assurance of confidentiality. This protection requires us to safeguard the information collected for the pregnant women and infants in the registries.

* Includes microcephaly, calcium deposits in the brain indicating possible brain damage, excess fluid in the brain cavities and surrounding the brain, absent or poorly formed brain structures, abnormal eye development, or other problems resulting from damage to the brain that affects nerves, muscles and bones, such as clubfoot or inflexible joints, and confirmed hearing loss.

**Includes miscarriage, stillbirths, and terminations with evidence of the birth defects mentioned above

Maps of Zika in the United States

Zika Cases Reported in the United States

Laboratory-confirmed Zika virus disease cases reported to ArboNET by state or territory (as of August 31, 2016)

Map of the United States showing Travel-associated and Locally acquired cases of the Zika virus.  The locations and number of cases can be found in the table below.

*See detailed map of the areas with active Zika virus transmission below.

Laboratory-confirmed Zika virus disease cases reported to ArboNET by state or territory — United States, 2015–2016 (as of August 31, 2016)§

States Travel-associated cases*
No. (% of cases in states)
(N=2,687)
Locally acquired cases†
No. (% of cases in states)
(N=35)
Alabama 24    (1) 0    (0)
Arizona 20    (1) 0    (0)
Arkansas 9      (<1) 0    (0)
California 152  (6) 0    (0)
Colorado 27    (1) 0    (0)
Connecticut 52    (2) 0    (0)
Delaware 11    (<1) 0    (0)
District of Columbia 11    (<1) 0    (0)
Florida 507  (19) 35    (100)
Georgia 69    (3) 0    (0)
Hawaii 11    (<1) 0    (0)
Idaho 2      (<1) 0    (0)
Illinois 51    (2) 0    (0)
Indiana 31    (1) 0    (0)
Iowa 14    (1) 0    (0)
Kansas 13    (<1) 0    (0)
Kentucky 20    (1) 0    (0)
Louisiana 26    (1) 0    (0)
Maine 11    (<1) 0    (0)
Maryland 85    (3) 0    (0)
Massachusetts 65    (2) 0    (0)
Michigan 43    (2) 0    (0)
Minnesota 40    (1) 0    (0)
Mississippi 18    (1) 0    (0)
Missouri 23    (1) 0    (0)
Montana 7      (<1) 0    (0)
Nebraska 8      (<1) 0    (0)
Nevada 13    (<1) 0    (0)
New Hampshire 8      (<1) 0    (0)
New Jersey 91    (3) 0    (0)
New Mexico 3      (<1) 0    (0)
New York 625  (23) 0    (0)
North Carolina 48    (2) 0    (0)
North Dakota 1      (<1) 0    (0)
Ohio 33    (1) 0    (0)
Oklahoma 20    (1) 0    (0)
Oregon 19    (1) 0    (0)
Pennsylvania†† 90    (3) 0    (0)
Rhode Island 28    (1) 0    (0)
South Carolina 31    (1) 0    (0)
South Dakota 1      (<1) 0    (0)
Tennessee 37    (1) 0    (0)
Texas 136  (5) 0    (0)
Utah 10    (<1) 0    (0)
Vermont 7      (<1) 0    (0)
Virginia 75    (3) 0    (0)
Washington 26    (1) 0    (0)
West Virginia 11    (<1) 0    (0)
Wisconsin 24    (1) 0    (0)
Territories Travel-associated cases*
No. (% of cases in territories)
(N=51)
Locally acquired cases†
No. (% of cases in territories)
(N=14,059)
American Samoa 0      (0) 47         (<1)
Puerto Rico 50    (98) 13,791**  (98)
US Virgin Islands 1      (2) 221       (2)

§Only includes cases meeting the probable or confirmed CSTE case definition and does not include asymptomatic infections unless the case is a pregnant woman with a complication of pregnancy
*Travelers returning from affected areas, their sexual contacts, or infants infected in utero
†Presumed local mosquito-borne transmission
††One additional case acquired through laboratory transmission
**During the week of August 24–31, 2016, the Puerto Rico Department of Health retroactively reported approximately 5,000 cases identified from June 4–August 6, 2016, resulting in a larger than normal increase in cases over prior weeks.

Active Zika Virus Transmission in Florida

Active Zika Virus Transmission in Florida

The Florida Department of Health has identified two areas in Miami with active transmission of Zika virus. See advice for people living in or traveling to these areas.

ZIKA in Your Area: What To Do

Key Facts

  • Zika virus is primarily spread to people through the bite of an infected mosquito.
  • Many people who get infected never have symptoms. In people who get sick, symptoms (fever, rash, joint pain, and red eyes) are usually mild and resolve completely.
  • Zika can cause serious birth defects in babies born to women who were infected with Zika virus during pregnancy. Zika has also been linked to Guillain-Barré syndrome (GBS), a rare disorder that can cause muscle weakness and sometimes paralysis. Most people fully recover from GBS, but some have permanent damage and, in some cases, people have died.
  • Zika can be passed through sex from a person who has Zika to his or her partners. Zika can be passed through sex, even if the infected person does not have symptoms at the time.
  • Because there is no vaccine or treatment for Zika, people living in or traveling to areas with Zika should take steps to prevent infection.

Mosquito

Prevent mosquito bites

Everyone living in or traveling to areas with Zika  should take steps to prevent mosquito bites:

  • Cover exposed skin by wearing long-sleeved shirts and long pants.
  • Use EPA-registered insect repellents that contain one of the following active ingredients: DEET, picaridin, IR3535, or oil of lemon eucalyptus or para-menthane-diol.  Always use as directed.
    • Pregnant and breastfeeding women can use all EPA-registered insect repellents according to the product label.
    • Most repellents can be used on children older than 2 months old. To apply, adults should spray insect repellent onto hands and then apply to a child’s face.
      • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
  • Use permethrin-treated clothing and gear (boots, pants, socks, tents). You can buy pre-treated items or treat them yourself.*
  • Stay and sleep in screened-in or air-conditioned rooms.
  • Sleep under a mosquito bed net if air conditioned or screened rooms are not available or if sleeping outdoors.
  • Mosquito netting can be used to cover babies younger than 2 months old in carriers, strollers, or cribs to protect them from mosquito bites.
  • Take steps to control mosquitoes in and around your home.

Prevent spread through sex

Prevent sexual transmission of Zika by using condoms or not having sex.

Condoms can reduce the chance of getting Zika from sex. To be effective, condoms should be used from start to finish, every time during vaginal, anal, and oral sex and the sharing of sex toys. Zika can be passed from a person with Zika before their symptoms start, while they have symptoms, and after their symptoms end.

  • All pregnant women with sex partners who live in or have traveled to an area with Zika should use condoms or not have sex during their pregnancy, even if their partners do not have Zika symptoms, or if their symptoms have gone away.
  • Couples who traveled to the area can consider using condoms or not having sex for at least 8 weeks after travel.
  • Anyone concerned about sexual transmission of Zika can consider using condoms or not having sex while there is Zika in the area.

 

Pregnant women: Get tested for Zika

Graphic of pregnant woman talking with her Doctor
  • All pregnant women who live in or have traveled to areas with Zika should receive routine prenatal care, including an ultrasound at 18–20 weeks.
  • Pregnant women who have symptoms of Zika (fever, rash, joint pain, red eyes) and live in or have traveled to areas with Zika should be tested as soon as symptoms start.
  • Pregnant women who do not have symptoms and live in or have traveled to an area with Zika should be tested at the start of prenatal care, and again halfway through the second trimester (18–20 weeks).

Pregnant women with possible exposure to Zika virus from sex should be tested if either they or their partners develop symptoms of Zika.

Discuss pregnancy planning with your healthcare provider

Graphic of a woman talking with her Doctor
  • Women and their partners should discuss pregnancy planning with a trusted doctor or other healthcare provider.
  • Women who want to get pregnant should talk with their healthcare provider about their goals for having children.
  • They should also talk with their healthcare provider about the potential risk of Zika virus infection during pregnancy as well as their partner’s potential exposures to Zika virus.
  • As part of counseling with healthcare providers, some women and their partners living in areas with Zika might decide to delay pregnancy.
  • The recommended times to wait before trying to get pregnant, based on whether either partner has had symptoms, are described below:

 

How Long to Wait Before Trying to Have a Baby When Living in an Area with Zika Transmission
Women Men
Zika symptoms At least 8 weeks after symptoms At least 6 months after symptoms start
No Zika symptoms Talk with doctor or healthcare provider Talk with doctor or healthcare provider

Women who do not want to get pregnant should talk with their doctor or healthcare provider about ways to prevent unintended pregnancy, including birth control methods. Women should consider safety, effectiveness, availability, and acceptability when choosing a birth control method.

If you or your partner becomes pregnant, talk with your doctor

  • You are at risk of getting Zika throughout your pregnancy. For this reason, CDC recommends testing at the first prenatal visit and a second test in the second trimester.
  • If you have symptoms of Zika (fever, rash, joint pain, or red eyes) at any time during your pregnancy, you should be tested for Zika. A healthcare provider may also test for similar diseases, like dengue or chikungunya.

Women who do not want to get pregnant

Women who do not want to get pregnant should talk with their doctor or healthcare provider about ways to prevent unintended pregnancy, including birth control methods. Women should consider safety, effectiveness, availability, and acceptability when choosing a birth control method.

If you get sick

If you feel sick and think you may have Zika
Graphic of Woman laying down on a bed
  • Talk to your doctor if you develop a fever with a rash, joint pain, or red eyes. Tell him or her about your travel.
  • Take acetaminophen (paracetamol) to relieve fever and pain. Do not take aspirin, products containing aspirin, or other nonsteroidal anti-inflammatory drugs, such as ibuprofen, until dengue can be ruled out
  • Get lots of rest and drink plenty of liquids.

During the first week of infection, Zika virus can be found in the blood and passed from an infected person to another mosquito through mosquito bites. An infected mosquito can then spread the virus to other people.

To help prevent others from getting sick, strictly follow steps to prevent mosquito bites during the first week of illness.

Mosquito Control

mosquito

Everyone can help control mosquitoes

  • Professionals from local government departments or mosquito control districts develop mosquito control plans, perform tasks to control young and adult mosquitoes, and evaluate the effectiveness of actions taken.
  • You, your neighbors, and the community can also take steps to reduce mosquitoes in and around your home and in your neighborhood.

Integrated Mosquito Management

Integrated Mosquito Management for Aedes aegypti and Aedes albopictus mosquitoes

Local governments and mosquito control programs often use an integrated mosquito management (IMM) or integrated vector management (IVM) approach to control mosquitoes. IMM uses a combination of methods to prevent and control mosquitoes that spread viruses, like Zika, dengue, and chikungunya. IMM is based on an understanding of mosquito biology, the mosquito life cycle, and the way mosquitoes spread viruses. IMM uses methods that, when followed correctly, are safe and have been scientifically proven to reduce mosquito populations.

Everyone can help control mosquitoes.

  • Professionals from local government departments or mosquito control districts develop mosquito control plans, perform tasks to control young and adult mosquitoes, and evaluate the effectiveness of actions taken.
  • You, your neighbors, and the community can also take steps to reduce mosquitoes in and around your home and in your neighborhood.

Estimated range of Aedes aegypti and Aedes albopictus

Conduct mosquito surveillance

Conduct mosquito surveillance

Mosquito control plans include steps that are taken before control efforts begin and before people start getting sick with a virus spread by mosquitoes. Professionals need to understand what types and numbers of mosquitoes are in an area. In order to find out this information, mosquito control experts conduct surveillance. Surveillance activities can include:

  • Monitoring places where adult mosquitoes lay eggs and where young mosquitoes can be found
  • Tracking mosquito populations and the viruses they may be carrying
  • Determining if EPA-registered insecticides will be effective

These activities help professionals determine if, when, and where control activities are needed to manage mosquito populations before people start getting sick. If professionals discover that local mosquitoes are carrying viruses (like dengue, Zika, or others), they start implementing other activities identified in their mosquito control plans.

Remove places where mosquitoes lay eggs

Remove places where mosquitoes lay eggs

Removing places where mosquitoes lay eggs is an important step. Mosquitoes lay eggs near water because young mosquitoes need water to survive. Professionals and the public can remove standing water.

  • Professionals at local government agencies and mosquito control districts may collect and dispose of illegally dumped tires, clean up and maintain public spaces like parks and greenways, and clean up illegal dumps and roadside trash.
  • You, your neighbors, and community can remove standing water. Once a week, items that hold water like tires, buckets, planters, toys, pools birdbaths, flower pot saucers, and trash containers should be emptied and scrubbed, turned over, covered, or thrown away.
  • If needed, a community clean up event can be held to remove large items like tires that collect water.
Control young mosquitoes

Control young mosquitoes

Once mosquito eggs hatch, they become larvae and then pupae. Both larvae and pupae live in standing water. Dumping or removing standing water in and around your home is one way to control young mosquitoes. For standing water that cannot be dumped or drained, a larvicide can be used to kill larvae. Larvicides[PDF – 1 page] are products used to kill young mosquitoes before they become biting adults.

The public and professionals can use US Environmental Protection Agency (EPA)-registered larvicides according to label instructions.

  • Professionals treat water-holding structures and containers in public places, like storm drains or urns in cemeteries. They may also treat standing water on private property as part of a neighborhood cleanup campaign.
  • People can treat fountains, septic tanks, and pool covers that hold water with larvicides.

Controlling young mosquitoes before they become adults, can minimize widespread use of insecticides that kill adult mosquitoes.

Control adult mosquitoes

Control adult mosquitoes

Adult mosquitoes can spread viruses (like dengue, Zika, or others) that make you sick. When surveillance activities show that adult mosquito populations are increasing or that they are spreading viruses, professionals may decide to apply adulticides[PDF – 1 page] to kill adult mosquitoes. Adulticides help to reduce the number of mosquitoes in an area and reduce the risk that people will get sick. The public and professionals can use US Environmental Protection Agency (EPA)-registered adulticides according to label instructions.

  • If mosquitoes are spreading viruses over larger areas, professionals spray adulticides by using backpack sprayers, trucks[PDF – 1 page], or airplanes[PDF – 1 page]
  • People can buy adulticides and use them inside and outside their homes.

Monitor control programs

To make sure that mosquito control activities are working, professionals monitor the effectiveness of their efforts to control both young and adult mosquitoes. For example, if an insecticide didn’t work as well as predicted, then professionals may conduct additional studies on insecticide resistance or evaluate the equipment used to apply insecticides..

Related Resources

Mosquito Control: What you need to know about using larvicides

Mosquito Control: What you need to know about using adulticides

Mosquito Control: What you need to know about truck-mounted spraying

Estimated range of Aedes aegypti and Aedes albopictus in the United States, 2016 fact sheet thumbnail

Estimated range of Aedes albopictus andAedes aegypti in the United States, 2016 Maps

Mosquito Control: What you need to know about filling tree holes

Keep mosquitoes out of your septic tank factsheet thumbnail

Keep mosquitoes out of your septic tank

Mosquito Control: What you need to know about indoor spraying

Mosquito Control: What you need to know about outdoor spraying

Mosquito Control: What state and local mosquito control programs do

Interim CDC Recommendations for Zika Vector Control in the Continental United States

Accompanying guidance to CDC Guidelines for Development of State and Local Risk-based Zika Action Plans *Does not include guidance specific to US territories

Early season mosquito control efforts can decrease the risk of eventual Zika transmission. In addition, effective control of Zika will depend on prompt and aggressive intervention when human cases are first identified. All at-risk communities should prepare for Zika virus activity, and should evaluate and prepare control plans for mosquito populations in their state as part of Zika Action Plan preparedness efforts.  A comprehensive review of health code, enforcement practices and property access will aid the implementation of a vector control plan.

Many states already have vector control programs. With the exception of states who have responded to past outbreaks of dengue and chikungunya, most state plans focus on control of mosquitoes for the prevention of West Nile virus (WNV). The biology and behavior of Aedes aegypti and Aedes albopictusare different from the mosquitoes that transmit WNV. Therefore, the tools used for surveillance of these species as well as strategies for control will be different from WNV mosquitoes.

Before mosquito season

  • State, tribes, and local governments should consider using an Integrated Vector Management (IVM) strategy as they develop their mosquito control plans (See Appendix).
  • Public health officials and vector control officials should develop a communications network to ensure timely exchange of information, and collaboratively share information to guide optimum vector control efforts. This network should be part of the state’s Incident Management structure, and should report efforts and plans to the state Incident Manager (IM).
  • To prepare for the possible introduction of Zika virus, states, tribes, and local governments should review historical data and maps regarding the presence of Aedes aegypti and Aedes albopictus. If maps are outdated and resources permit, plan new surveys and assessments to be conducted during mosquito season.
  • Responding officials should review existing staffing capacity, resource allocation, and technical expertise at the local level for vector control and consider use of intergovernmental agreements for vector control to help adjacent counties outside their jurisdiction, as well as pre-positioning contracts with vendors to supply additional capacity.
  • Responding officials should link vector control efforts with communication efforts. This includes ensuring public education campaigns include information not just on personal protection measures, but also how citizens may reduce or eliminate breeding sites for Ae. aegypti and Ae. albopictus, and to motivate the community to remove and dispose of any water holding containers.

Mosquito Season

  • Using the plan previously developed, survey and map presence of Aedes aegypti and Aedes albopictus within the state.
  • Actively engage community to encourage removal of larval habitat and Aedes breeding sites, including community cleanup campaigns (tire removal, trash pickup, removal and cleaning of small and large containers). Leverage partnerships with local governments and non-profits for support.
  • If resources and technical expertise permits, conduct rapid insecticide resistance testing for local mosquito populations, in order to know the pesticides most likely to be effective in the event of Zika transmission.
  • Use larvicides in containers and bodies of water that cannot be removed or dumped.

Confirmed transmission (first case, or several cases in a single household or building)

  • Implement Targeted Control efforts around the case-patient’s home or building. Conduct intensified larval and adult mosquito control in a 150 yard radius (or other boundary as deemed appropriate) around the case patient home.  Targeted control activities involving home visits should be closely coordinated with concurrent educational efforts and messaging.
  • Consider adding community-based adult mosquito control consisting of outdoor residual spraying, and space spraying if necessary.
  • Intensify larviciding and source reduction efforts.
  • Consider targeted indoor residual spraying in areas where A/C and screens aren’t widely available.

Widespread transmission within a county or jurisdiction

  • Vector control efforts should align with state, tribal, and local government decisions regarding boundaries for declaring an area as a site of “active Zika transmission”. This may model county lines, or be a zipcode designation. At this phase, officials should plan to intensify and expand vector control efforts within the areas of active transmission.
  • In addition to continuing to target case-patient homes and the surrounding vicinity, area-wide treatments with larvicides and adulticides using application methods appropriate for the scale of the treatment area should be considered. Control plans should be tailored to the local needs, and might require truck or aerial spraying (aerial for areas > 2,000 acres) or a combination of both.
  • Monitor for effectiveness of treatments through trapping and retreat if mosquito numbers begin to increase again.
  • For areas where A/C and screens aren’t widely available, consider adding targeted indoor residual spraying to vulnerable homes.

Widespread transmission within multiple counties or the state

  • Expand vector control efforts for regional or state coverage.

Appendix

Effective mosquito management programs based on Integrated Vector Management (IVM) principles may help prevent the introduction of Zika to an area. IVM principles include approaching mosquito control through careful planning, and using a variety of interventions targeting both larval and adult mosquito control, and including both chemical and non-chemical methods. Properly planned and executed, IVM ensures a more effective level of control than can be achieved by one single approach. States, tribes, and local governments should develop plans tailored to their individual needs, and should consider basing those plans on the principles of IVM.

IVM is ideally anchored by a mosquito monitoring program providing data that describe local conditions and habitats that produce Aedes mosquitoes, as well as the abundance of those mosquitoes over the course of a season. These data can help inform decisions about implementing mosquito control activities appropriate to the situation. The implementation of an effective IVM program for Aedes requires trained staff with a knowledge of the mosquito life cycle and expertise in monitoring methods. Details for how to conduct assessment and control activities for both larval and adult Aedes mosquitoes may be found on CDC’s Chikungunya website.

Immature Mosquito Monitoring

Larval monitoring can help state, tribal, and local governments monitor Aedes activity and make early decisions for control, even in advance of suspected Zika cases in humans. This involves sampling a wide range of aquatic habitats, and requires trained inspectors to identify larval production sites, collect larval specimens on a regular basis from known larval habitats, and to regularly look for new sources. This information can be used to determine where and when source reduction or larval control efforts should be implemented. Common methods for collecting information on the number and locations of larvalAe. aegypti and Ae. albopictus are ovitraps and larval/pupal surveys.

Adult Mosquito Monitoring

Adult mosquito monitoring is used to determine the abundance adult vector mosquitoes, and identify areas where control measures are needed. It is also useful to assess the effectiveness of intervention methods. Currently, testing mosquitoes for Zika virus is not currently recommended, as this virus does not have a known animal reservoir outside of humans in the United States and there is no expected advantage to be obtained over good human surveillance programs.

Various methods are available for monitoring adult mosquitoes. Traps targeting adult Culex species are not affective at capturing Ae aegypti and Ae. albopictus.  The most frequently used trap for adult Aedes surveillance is the BG Sentinel trap, but other trap types are available. Adult mosquito surveillance should consist of a series of collecting sites at which mosquitoes are sampled on a regular schedule. Fixed trap sites allow monitoring of trends in mosquito abundance over time and are essential for obtaining information to guide control efforts. Additional trap sites can be utilized on an ad hoc basis to provide additional information about mosquito activity and effectiveness of control efforts.

Mosquito Control Activities

Mosquito control should ideally be conducted during mosquito season, even before cases of Zika are recognized, and be based on the results of larval and adult mosquito monitoring programs that have identified areas in need of control. Additionally, at the point of the first human case of Zika, more routine mosquito control efforts must be quickly and aggressively amplified to prevent risk levels from increasing to the point of a widespread human disease outbreak.

Larval Mosquito Control

The objective of the larval mosquito control is to manage mosquito populations before they emerge as adults. This can be an efficient method of managing mosquito populations if the mosquito breeding sites are accessible. However larval control alone may not attain the levels of mosquito population reduction needed to maintain Zika risk at low levels, and must be accompanied by measures to control the adult mosquito populations as well. In outbreak situations, larval control complements adult mosquito control measures by preventing new vector mosquitoes from being produced. However, larval control alone is unlikely to be able to stop Zika outbreaks once virus amplification has reached levels causing human infections.

Numerous methods are available for controlling larval mosquitoes.

  • Source reduction: Source reduction is the elimination or removal of habitats that produce mosquitoes. This can range from draining and scrubbing water holding containers on a weekly basis to properly disposing of discarded tires, rain barrels, and trash containers that may harbor rain water. This can be difficult to accomplish with the Zika virus vector Ae. aegypti that readily utilizes very small water containers. Active community engagement, as well as ensuring community access to trash services for removal of debris, are critical to the success of a source reduction campaign. Source reduction may be improved through home visits to examine possible mosquito breeding sites and educating homeowners.
  • Larvicide Application: For situations not conducive to source reduction, pesticides registered by EPA for larval mosquito control may be applied when larvae are detected or added to containers that could potentially serve as breeding sites. Several larval mosquito control pesticides are available. (See Table 1.) Methods for delivering larvicides include the use of hand-held application devices, from truck-mounted sprayers, from aircraft, or from a combination of methods. More details are provided below.
  • Combined Approach: A combination approach utilizing source reduction and larviciding that is tailored to local contexts and the provision of adequate field staff with proper training is required to properly identify larval production sites and implement the appropriate management tools for that site.

Adult Mosquito Control

Source reduction and larvicide treatments alone are unlikely to be adequate to maintain adult mosquito populations at levels sufficiently low enough to limit virus amplification. The objective of the adult mosquito control component of an IVM program is to complement the larval management program by reducing the abundance of adult, actively biting mosquitoes in an area, thereby reducing the number of eggs laid in breeding sites. In addition, during an outbreak, adult mosquito control is crucial to immediately reduce the abundance of biting, infected adult mosquitoes. A list of EPA registered chemicals available for controlling adult mosquitoes is in Table 2. Numerous methods are available for controlling adult Aedes mosquitoes.

  • Targeted Outdoor Residual Spraying: In situations where long-lasting control is desired (at the case-patient household or building level, for example) an approach aimed at outdoor spraying of surfaces likely to serve as adult mosquito resting sites may be achieved with hand-held application devices (Trout et al. 2010) at the target and in a 150 yard radius around the target. Ideally, pesticide decisions should be preceded by an assessment of possible resistance to the chemicals. Targeted adulticide treatments should be accompanied by larval reduction methods as described above. In these situations (i.e. providing a barrier around a pregnant woman’s or case-patient’s home), in order to arrest viral spread, this method requires aggressive attention and rapid action. (Vasquez-Prokopec 2010)
  • Indoor Residual Spraying: Indoor residual spraying should be considered for homes that do not have adequate screening or air conditioning. Two chemicals with EPA registration allowing indoor use for mosquitoes are deltamethrin and bifenthrin.  Spraying should target sites within the home where mosquitoes rest.  They include the back of closets, under furniture and other dark undisturbed sites behind furniture and in corners. (Vazques-Prokopec 2010)
  • Widespread Outdoor Application: In situations where adult Aedes mosquito populations are very high or more widespread local transmission of Zika is recognized, in addition to the household or building targeted approach, more widespread adulticide applications using pesticides registered by EPA can be used. Pesticides for adult mosquito control can be applied to wider areas using hand-held application devices, from truck-mounted sprayers, from aircraft, or from a combination of methods. This type of spraying is known as space spraying, as opposed to residual spraying described above, and its effect is transient when used without concurrent larval control (i.e., the insecticide must come into contact with a mosquito at the time of being sprayed in order to have an impact).
    • Hand-held devices are useful to manage relatively small areas, but are limited in their capacity to treat large areas quickly during an outbreak.
    • Truck-based applications may reach larger areas, but may have gaps in coverage due to limitations of the road infrastructure.
    • Aerial application of mosquito control adulticides is required when large areas must be treated quickly.  Applications using trucks and aircraft should be timed around dusk and/or dawn.
    • Both truck and aerially-applied pesticides for adult mosquito control are applied using ultra-low-volume (ULV) technology in which a very small volume of pesticide is applied per acre in an aerosol of minute droplets designed to contain sufficient pesticide to kill mosquitoes that are contacted by the droplets. Information describing ULV spray technology and the factors affecting effectiveness of ground and aerially-applied ULV pesticides is reviewed in Mount et al. 1996, Mount 1998, and Bonds 2012.

Risk and Safety of Vector Control Pesticides and Practices

Insecticides to control larval and adult mosquitoes are registered specifically for that use by the U.S. Environmental Protection Agency (EPA). Instructions provided on the product labels prescribe the required application and use parameters, and must be strictly followed. Pesticide use should be restricted to trained and licensed technicians, according to state, tribal, or local legal requirements. Research has demonstrated that ULV application of mosquito control adulticides did not produce detectable exposure or increases in asthma events in persons living in treated areas (Karpati et al. 2004, Currier et al. 2005, Duprey et al. 2008).

Legal Action to Achieve Access or Control

Individually-owned private properties may be major sources of mosquito production. Examples include accumulations of discarded tires or other trash, neglected water features that become stagnant and produce mosquitoes. Local public health statutes or public nuisance regulations may be employed to gain access for surveillance and control, or to require the property owner to mitigate the problem. Proactive communication with residents and public education programs may alleviate the need to use legal actions. However, legal efforts may be required to eliminate persistent mosquito production sites.

Insecticide Resistance Management

In order to delay or prevent the development of insecticide resistance in vector populations, integrated vector management programs should include a resistance management component (Florida Coordinating Council on Mosquito Control 1998). Ideally, this should include annual monitoring of the status of resistance in the target populations, or resistance assessments in local areas ahead of decisions for chemical applications.

CDC has developed an assay to determine if a particular active ingredient is able to kill mosquito vectors. The technique, referred to as the CDC bottle bioassay, is simple, rapid, and economical compared with alternatives. The results can help guide the choice of insecticide used for spraying. A practical laboratory manual that describes how to perform and interpret the CDC bottle bioassay is available online[PDF – 28 pages]. For additional information about obtaining and performing the bottle bioassay, contact CDC at bottleassay@….

Table 1 Insecticides targeting larval mosquitoes

Active Ingredient Chemical Type
Bacillus thruengensis isralensis Microbial
Bacillus sphaericus Microbial
Spinosyn Microbial
Oils Surface film
Novaluron Insect growth regulator
Methoprene Insect growth regulator
Temephos Organophosphate

Table 2 Insecticides targeting adult mosquitoes

Active Ingredient Use Chemical Type
Deltamethrin Space spray/residual spray Pyrethroid
Etofenprox Space spray Pyrethroid
Permethrin Space spray Pyrethroid
d-Phenothrin (Sumethrin) Space spray Pyrethroid
Pyrethrins/Pyrethrum Space spray Pyrethroid
Chlorpyrifos Space spray Organophosphate
Malathion Space spray Organophosphate
Naled Space spray Organophosphate
Alpha-cypermethrin Residual spray Pyrethroid
Bifenthrin Residual spray Pyrethroid
Lambda-cyhalothrin Residual spray Pyrethroid
Tau-fluvalinate Residual spray Pyrethroid
Imidacloprid/beta-cyfluthrin Residual spray Neonicotinoid/Pyrethroid mix

References

Bonds JA. 2012. Ultra-low-volume space sprays in mosquito control: a critical review. Med Vet Entomol. 26(2):121-30.

Currier M, McNeill, M, Campbell D, Newton N, Marr JS Perry E, Berg SW, Barr DB, Luber GE, Kieszak MA, Rogers HS, Backer LC Belson MG Bubin C Azziz-Baumgartner E, Duprey ZH. 2005. Human exposure to mosquito-control pesticides- Mississippi, North Carolina, and Virginia, 2002 and 2003. MMWR. 54:529-532.

Duprey Z, Rivers S, Luber G, Becker A, Blackmore C, Barr D, Weerasekera G, Kieszak S, Flanders WD, Rubin C. 2008. Community aerial mosquito control and naled exposure. J Am Mosq Control Assoc. 24:42-46. Doi:10.2987/5559.1

Florida Coordinating Committee Mosquito Control. 1998. Florida mosquito control: the state mission as defined by mosquito controllers, regulators, and environmental managers[PDF – 259 pages]. Gainesville, FL: University of Florida. Accessed 5/7/2013

Karpati AM, Perrin MC, Matte T, Leighton J, Schwartz J, Barr RG. 2004. Pesticide spraying for West Nile virus control and emergency department asthma visits in New York City, 2000. Environ Health Perspect. 112(11):1183-7.

Mount GA. 1998. A critical review of ultralow-volume aerosols of insecticide applied with vehicle-mounted generators for adult mosquito control. J Am Mosq Control Assoc. 14(3):305-34.

Mount GA, Biery TL, Haile DG. 1996. A review of ultralow-volume aerial sprays of insecticide for mosquito control. J Am Mosq Control Assoc. 12(4):601-18.

Trout RT, Brown GC, Potter MR, Hubbard JL. 2007. Efficacy of two Pyrethroid insecticides applied as barrier treatments for managing mosquito (Dipters: Culicidae) populaitons in suburban residential properties.  J. Med. Entomo. 44:470-477

Vazques-Prokopec GM, Kitron U, Montgomery B, Horne P, Ritchie SA. 2010.  Quantifying the spatial dimension of dengue virus epidemic spread within a tropical urban environment. PLoS Negl. Trop. Dis. 4:  e920. doi:10.1371/journal.pntd.0000920

Insecticide Resistance

Person in lab holding a glass bottle.

The use of insecticides to kill mosquitoes that spread Zika, dengue, and chikungunya viruses, is one part of an integrated mosquito management program. Insecticides may be used by professionals and by homeowners. Insecticides can be applied by hand (indoor and outdoor sprays and foggers), by truck, or by aerial (airplane) spraying.

Over time and repeated use, insecticide resistance can occur in mosquito populations. Insecticide resistance is an overall reduction in the ability of an insecticide product to kill mosquitoes. This means that, when used as directed, the product no longer works, or only partially works. Insecticide resistance can be product specific, or it can develop to a certain class(es) of product.

In order to delay or prevent the development of insecticide resistance in vector populations, integrated vector management programs should include a resistance management component (Florida Coordinating Council on Mosquito Control 1998). Ideally, this should include annual monitoring of the status of resistance in target populations to:

  • Provide baseline data for program planning and pesticide selection before the start of control operations.
  • Detect resistance at an early stage so that timely management can be implemented.
  • Continuously monitor the effect of control strategies on insecticide resistance.

How Insecticide Resistance is Measured

Monitoring for resistance in the vector population is essential and is useful in determining the potential causes for control failures, should they occur. CDC has developed an assay to determine if a particular insecticide formulation (combination of the active ingredient in the insecticide and inactive ingredients) is able to kill mosquito vectors. The technique, referred to as the CDC bottle bioassay, is simple, rapid, and economical compared with alternatives. The results can help guide the choice of insecticide used for spraying.

How the Bottle Bioassay Works

  • A bottle is coated with a known amount of insecticide. Mosquitoes are then put into the bottle and observed until for a pre-determined period of time (diagnostic time).
  • Resistance is determined by the percentage of mosquitoes that die (mortality rate) in the diagnostic time.

Insecticide Resistance Testing in Puerto Rico

Beginning in February of 2016, CDC Entomologists located at the Dengue Branch carried out Bottle Bioassays tests to determine the presence of insecticide resistance of Aedes aegypti to the most commonly used EPA-approved insecticides for mosquito control. CDC entomologists collected mosquitoes from many locations throughout Puerto Rico and brought them to the laboratory. Bioassay testing was performed in the laboratory with laboratory reagent grade chemicals and all organisms used were discarded in the laboratory waste at the Dengue Branch.

Results from testing show that the mosquitoes collected from 38 locations in 23 of the 78 municipalities in Puerto Rico are either resistant or partially resistant to many insecticides tested. Resistance has been observed in permethrin and malathion, two commonly used insecticides in Puerto Rico.

Results are presented below as maps showing whether Aedes aegypti were susceptible, partially resistant, or resistant to specific insecticides from the municipalities shown.


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MEDICAL: DISEASES: ZIKA VIRUS : GUIDES : DIRECTORIES : PUBLICATIONS : MEDICAL: RESOURCES: Zika Virus for Healthcare Providers FROM Centers for Disease Control and Prevention. National Center for Emerging and Zoonotic Infectious Diseases (NCEZID). Division of Vector-Borne Diseases (DVBD)

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