Zika Virus Disease

Zika virus disease (Zika) is a disease caused by Zika virus that is spread to people primarily through the bite of an infected Aedes species mosquito. The most common symptoms of Zika are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito. 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. Once a person has been infected, he or she is likely to be protected from future infections.

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.

In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infection in Brazil and on Feb 1, 2016, the World Health Organization (WHO) declared Zika virus a public health emergency of international concern (PHEIC). Local transmission has been reported in many other countries and territories. Zika virus likely will continue to spread to new areas.

Specific areas with ongoing Zika virus transmission is ongoing are often difficult to determine and are likely to change over time. If traveling, please visitthe CDC Travelers' Health site for the most updated travel information.

What we know

• No vaccine exists to prevent Zika virus disease (Zika).
• Prevent Zika by avoiding mosquito bites (see below).
• Mosquitoes that spread Zika virus bite mostly during the daytime.
• Mosquitoes that spread Zika virus also spread dengue and chikungunya viruses.
• Prevent sexual transmission of Zika by using condoms or not having sex

Steps to prevent mosquito bites

When in areas with Zika and other diseases spread by mosquitoes, take the following steps:

• Wear long-sleeved shirts and long pants.
• Stay in places with air conditioning or that use window and door screens to keep mosquitoes outside.
• Sleep under a mosquito bed net if you are overseas or outside and are not able to protect yourself from mosquito bites.
• Use Environmental Protection Agency (EPA)-registered insect repellents. When used as directed, EPA-registered insect repellents are proven safe and effective, even for pregnant and breast-feeding women.
  • 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 before applying insect repellent.
• If you have a baby or child:
  • Do not use insect repellent on babies younger than 2 months of age.
  • Dress your child in clothing that covers arms and legs, or
  • Cover crib, stroller, and baby carrier with mosquito netting.
  • 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.
• Treat clothing and gear with permethrin or purchase permethrin-treated items.
  • Treated clothing remains protective after multiple washings. See product information to learn how long the protection will last.
  • If treating items yourself, follow the product instructions carefully.
  • Do NOT use permethrin products directly on skin. They are intended to treat clothing.

Even if they 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 uninfected mosquitoes.

If you have Zika, protect others from getting sick

• 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, avoid mosquito bites during the first week of illness.
• Zika virus can be spread during sex by a man infected with Zika to his sex partners.
  • We do not know how long the virus is present in the semen of men who have had Zika.
  • We do know that the virus can stay in semen longer than in blood.
• To help prevent spreading Zika from sex, you can use condoms the right way every time you have sex. This includes vaginal, anal, and oral (mouth-to-penis) sex. Not having sex is the best way to be sure that someone does not get sexually transmitted Zika virus.

If you are a man who lives in or has traveled to an area with Zika

• If your partner is pregnant, either use condoms the right way every time you have vaginal, anal, and oral (mouth-to-penis) sex or they should not have sex during the pregnancy.
  • Even if they 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 uninfected mosquitoes.

If you are concerned about getting Zika from a male sex partner

• You can use condoms the right way every time you have vaginal, anal, and oral (mouth-to-penis) sex.  Condoms also prevent HIV and other STDs.  Not having sex is the best way to be sure that you do not get sexually transmitted Zika virus.
  • Pregnant women should talk to a doctor or healthcare provider if they or their male sex partners recently traveled to an area with Zika, even if they don’t feel sick.

Information for travelers

• Traveling? Visit CDC's Travelers Health website to see if the country you plan to visit has any travel health notices.
• Even if they 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 uninfected mosquitoes.
• CDC has posted maps that show elevation levels in countries with Zika.

Symptoms

• Most people infected with Zika virus won’t even know they have the disease because they won’t have symptoms. The most common symptoms of Zika are fever, rash, joint pain, or conjunctivitis (red eyes). Other common symptoms include muscle pain and headache. The incubation period (the time from exposure to symptoms) for Zika virus disease is not known, but is likely to be a few days to a week.
• • See your healthcare provider if you are pregnant and develop a fever, rash, joint pain, or red eyes within 2 weeks after traveling to a place where Zika has been reported. Be sure to tell your health care provider where you traveled.
• The illness is usually mild with symptoms lasting for several days to a week after being bitten by an infected mosquito.
• 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.
• Zika virus usually remains in the blood of an infected person for about a week but it can be found longer in some people.
• Once a person has been infected, he or she is likely to be protected from future infections.

Diagnosis

• The symptoms of Zika are similar to those of dengue and chikungunya, diseases spread through the same mosquitoes that transmit Zika.
• See your healthcare provider if you develop the symptoms described above and have visited an area where Zika is found.
• If you have recently traveled, tell your healthcare provider when and where you traveled.
• Your healthcare provider may order blood tests to look for Zika or other similar viruses like dengue or chikungunya.

Treatment

• There is no vaccine to prevent or medicine to treat 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 have Zika, prevent mosquito bites for the first week of your illness.
• During the first week of infection, Zika virus can be found in the blood and passed from an infected person to a mosquito through mosquito bites.
• An infected mosquito can then spread the virus to other people.