Zika Virus Outbreak

What is the Zika virus?

The Zika virus is a mosquito-borne flavivirus that was discovered in Uganda’s Zika forest in 1947. Prior to 2015, outbreaks of Zika virus infection had been reported in parts of Africa, Asia, and the South Pacific. In May of 2015, an outbreak was reported in northeastern Brazil, and the virus has continued to spread throughout the Americas. Updates on affected countries and territories are available online from the CDC and the Pan American Health Organization (PAHO)

How is the Zika virus transmitted?

The Zika virus is transmitted to humans primarily through the bite of an infected Aedes species mosquito (Ae aegypti and Ae aldopticu), both of which are present in the United States. Human-to-human transmission of the virus can also occur through sexual contact, and from a mother to her fetus during pregnancy.

The incubation period for the Zika virus is unknown, butis thought to be a few days to a week. The CDC estimates that approximately one in five people infected with the virus will develop symptoms of Zika virus infection.

What are the symptoms of Zika virus infection?

The following are the most common symptoms:

• Fever
• Maculopapular rash
• Joint pain
• Conjunctivitis
• Muscle pain
• Headache

These symptoms are similar to the symptoms of dengue and chikungunya, which are transmitted to humans by the same species of mosquitoes that transmits the Zika virus.

In most cases, people who have Zika virus infection only have mild symptoms, typically lasting for several days to a week. A person who has Zika virus infection is not likely to develop symptoms severe enough to require hospitalization. Deaths from the infection are rare.

In some areas (e.g., Brazil), there has been an increase in reported cases of Guillain-Barré syndrome in patients who have been infected by the Zika virus. However, a direct link between Zika virus infection and Guillain-Barré syndrome has not been established.

What are the risks of Zika virus infection during pregnancy? 

Currently, data on pregnant women infected with the Zika virus is limited. According to the CDC, there is no evidence that shows pregnant women are more susceptible to the virus or that Zika virus infection is more severe during pregnancy. However, Zika infection during pregnancy can cause microcephaly and other severe brain defects in the fetus. The CDC recommends that all pregnant women consider postponing travel to areas where Zika virus infection has been reported. Pregnant women in these areas should take steps to avoid mosquito bites.

Who should be tested for Zika?

Anyone with symptoms typical of the Zika virus who was in an active transmission area within 2 weeks of the onset of symptoms or had sex with an individual who traveled to an affected area, may be infected and should be tested. Asymptomatic pregnant women who have traveled to an active Zika transmissionaffected area or had sexual contact with someone who was in an affected area should be tested within two weeks of possible exposure. Testing is not recommended in asymptomatic women who are not pregnant or in asymptomatic men and children.

How is Zika virus infection diagnosed?

Preliminary diagnosis of Zika virus infection is based on clinical findings and epidemiologic characteristics (e.g., travel history). Diagnostic testing for Zika includes a serum test within a week after onset of symptoms or urine testing within two weeks of onset of symptoms. See the CDC algorithm for testing in women who are pregnant. If you suspect one of your patients has this infection, you should notify your state or local health department to facilitate testing for the virus and disease surveillance.

What is the treatment for Zika virus infection?

Supportive care is the primary treatment for Zika virus infection. Currently, no antiviral medication is available.

Is there a vaccine or medication that prevents Zika virus infection?

No. Currently, no vaccine or medication to prevent infection with the Zika virus is available. There is a vaccine in development that has been approved for human trials.

How can Zika virus infection be prevented?

One way to prevent Zika virus infections is to avoid mosquito bites. People living in or traveling to areas that are affected by the Zika virus should take steps to avoid mosquito bites, including:

• Stay in air-conditioned or screened-in places. 
• Use insect repellent according to label instructions. This includes repellents that contain DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), or 2-undecanone.
• Wear light-colored pants and shirts with long sleeves.
• Treat clothing with permethrin (a spray that repels mosquitoes) according to label instructions or buy permethrin-treated clothing.

Another way to prevent Zika virus infections is to avoid sexual transmission. The Zika virus can be sexually transmitted by an infected individual, even if they do not have symptoms. Transmission can occur during vaginal, oral, or anal sex, as well as by the sharing of sex toys. People living in or traveling to areas affected by Zika should take steps to avoid sexual transmission, including the following:

• Use condoms or abstain from sex.
• Use dental dams for oral sex.
• Do not share sex toys.