Zika 101

Anne Schuchat

By Dr. Anne Schuchat

The Zika virus is spread to people through the bite of infected mosquitos. About one in five people who get infected with Zika virus will show symptoms.

In the past several weeks, increased cases of Zika virus disease (Zika) have been reported in South and Central America, and to a limited degree, in the Commonwealth of Puerto Rico, a U.S. territory, and the U.S. Virgin Islands. Zika is a little known illness spread by a certain type of mosquito. Although most people who may be exposed to Zika virus will have only mild or no symptoms, there has been evidence linking Zika virus to negative effects on pregnancies in some cases, which has received widespread public attention. We understand that this news is concerning, especially to pregnant women and their families who may travel to or live in affected areas. Here are some answers to common questions about Zika.

What is Zika?

The Zika virus is spread to people through the bite of infected mosquitos. About one in five people who get infected with Zika virus will show symptoms. Most of those who get sick experience only mild symptoms that last about a week. The most common symptoms are fever, rash, joint pain, and red eyes (conjunctivitis). It's rare for someone infected with Zika to become seriously sick or die. Zika is not spread through routine direct person-to-person contact.

Zika and Pregnancy

While anyone can be infected with Zika, what makes it stand out from other mosquito-borne illnesses is the effect it appears to have on pregnancy. We know that Zika can spread from a pregnant mother to her baby, and that infection during pregnancy may be linked to birth defects, such as a condition called microcephaly (when a baby's head is smaller than expected when compared with babies of the same sex and age). Our understanding of the link between Zika and pregnancy is evolving.

Because of the possible risk to unborn babies, the U.S. Centers for Disease Control and Prevention (CDC) recommends that women who are pregnant or trying to become pregnant consider postponing travel to areas with local Zika transmission. If you are pregnant and must travel to one of these areas, talk to your health care provider first and strictly follow steps to prevent mosquito bites. As we learn more about this disease, our guidance may change based on new information important for the public to know.

How to Protect Yourself from Zika

Because there are currently no vaccines or treatment for Zika, the best way to protect yourself is to prevent mosquito bites. You can do this by wearing long-sleeved shirts and long pants and treating your clothing and other items with permethrin. Use an Environmental Protection Agency (EPA)-registered insect repellant as directed. You shouldn't use insect repellant on babies younger than 2 months of age; instead, dress your baby in clothing that covers arms and legs and cover the crib, stroller, or baby carrier with mosquito netting.

If you've recently traveled to an area with Zika and develop a rash, joint pain, or red eyes, tell your doctor that you traveled to a country with Zika virus. Because the symptoms of Zika are similar to dengue and chikungunya, special blood tests may be needed.

If you get sick with Zika, make sure to get plenty of rest and fluids, and take medicines like acetaminophen or paracetamol to reduce fever and pain. Don't take aspirin or other non-steroidal anti-inflammatory drugs like ibuprofen. You can also prevent others from getting sick by avoiding mosquito bites during the first week of illness following the same steps outlined above, because Zika virus can stay in the blood during the first week of infection.

Zika in the Continental U.S.?

Although Zika has been in the news recently, outbreaks of Zika have previously been reported in tropical Africa, Southeast Asia, and the Pacific Islands. In May 2015, the Pan American Health Organization issued an alert for the first confirmed infection in Brazil. Since then, local transmission of Zika virus has been reported in more than 20 other countries and territories in Latin America and the Caribbean. Because the mosquitoes that spread Zika are found throughout the tropics, outbreaks of the disease will likely continue.

Zika is currently not found in the continental United States, but cases of Zika have been reported in returning travelers. Because of the recent outbreaks in the Americas, we expect to see more cases of Zika in travelers visiting or returning to the United States. Many areas in the continental U.S., primarily in the Southeast and Gulf Coast regions, have mosquitoes that can become infected with and spread Zika virus, so it is possible that these imported cases could result in local spread of the virus in some areas of the United States. Limited local transmission may occur in the mainland United States, but we believe it is unlikely that we will see widespread transmission of Zika in the mainland United States. Recent outbreaks in the United States of chikungunya and dengue were quite small compared with outbreaks in South America.

What HHS Is Doing

In response to recent outbreaks of Zika, CDC issued travel health notices for people traveling to areas where Zika virus transmission is ongoing. Specific areas where Zika virus transmission is ongoing are often difficult to determine and are likely to keep changing over time. It's important to keep up to date on CDC's travel notices for recommendations on what to do if you travel to an area with Zika. CDC has also provided guidance, in consultation with major medical societies, to the health care community.

We are working with countries with widespread transmission of Zika to learn as much about the virus as we can, as quickly as we can. Our goal is to prevent Zika infection, especially among women who are pregnant or thinking about getting pregnant, and to help those who have traveled to areas with widespread transmission learn as quickly as possible if they have been infected. We are preparing for additional potential Zika cases in the United States by working with state and local health departments and educating doctors and other health care providers on how to test and care for patients. We are working with government scientists, outside experts, and the private sector to speed the development of tests, treatments and vaccines, and improved mosquito-control methods. CDC and the National Institutes of Health are also increasing their support for scientific research to learn more about this disease so that advice can be updated and new safeguards and medical responses can be developed. NIH is also supporting research to develop rapid diagnostics, treatments, and vaccine candidates.

Get the most up to update information on the CDC website at http://www.cdc.gov/zika/.

Zika 101 was originally posted in the Jan. 28, 2016 version of the U.S. Department of Health and Human Services (HHS) blog.

Dr. Anne Schuchat is the Principal Deputy Director at the CDC.