Feature Article: Zika Virus — What You Should Know

* Updated April 18, 2016 with new information from the CDC.

Reports about the spread of Zika virus in Central and South America, and concerns about the potential effects on infants of women infected during pregnancy, have led to many questions among parents and other community members. As the situation continues to evolve, the Centers for Disease Control and Prevention (CDC) will deliver updates.

What is Zika virus and how does it spread?

Zika virus is a type of Flavivirus. More commonly known members of this family of viruses include West Nile virus, yellow fever virus and dengue virus. Each of these viruses is most commonly spread through the bite of an infected mosquito.

Zika virus is spread by the Aedes species of mosquitoes, and unlike many other mosquitoes, this type typically bites during the daytime when people are also most active. Mosquitoes become infected after biting an infected person, and then they spread the virus to another person when they bite again.

At this time, other ways that Zika virus spreads are not fully understood. Transmission from mother to fetus has been confirmed, while transmission has been documented through sexual contact has been documented and from mother to fetus; however, significance of transmission via these channels sexual contact as well as whether the virus can also spread through blood transfusions is still being investigated. 

What are the symptoms of Zika virus?

About 1 in 5 people with Zika virus develops symptoms, such as fever, rash, joint pain or conjunctivitis (pink eye). Other symptoms could include muscle pain and headache. Symptoms typically last several days to a week.

Two potential outcomes of Zika virus infection have been worrisome:

• Guillain-Barré Syndrome (GBS) — a condition characterized by weakened muscles and sometimes paralysis, GBS typically resolves after a few weeks. However, the condition is alarming and some people experience permanent nerve damage.
• Microcephaly — a condition in which an infant is born with a significantly smaller head size compared with other infants of the same age and gender. Often, this condition indicates a smaller than normal or underdeveloped brain.

On April 13, 2016, the CDC concluded that Zika virus is a cause of microcephaly and other severe fetal brain defects. Researchers and public health agencies are still studying the connection between Zika infections and GBS.

Why is Zika virus causing infections now?

Zika virus was first identified in Africa in 1947, with the first human cases diagnosed in 1952. Because the symptoms of Zika virus are typically minor and are similar to some other mosquito-borne infections, it is likely that the number of cases diagnosed is only a small percentage of those that have occurred. However, Zika virus seems to be spreading more rapidly for reasons that remain uncertain, but are likely due at least in part to increased international travel.

Who is at risk?

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

Adults are more likely to require medical attention for Zika virus infections, and unborn babies of pregnant women are considered to be at greater risk because of the link between microcephaly and infants born to mothers who were infected during pregnancy. For this reason, pregnant women are being advised not to travel to areas with Zika outbreaks and to abstain from sex or have protected sex with men who may be infected due to recent travel to an infected area.

Is there a vaccine?

No. A vaccine is not available to protect against Zika virus. But because Zika virus is a flavivirus, and two flavivirus vaccines exist (yellow fever and dengue), the path to a Zika vaccine will probably be a straight one.

How can my family stay healthy?

For people who live in or plan to travel to areas where Zika virus is present, the best way to prevent infection is to avoid mosquito bites. You can protect yourself by wearing long pants and long-sleeved shirts and using insect repellants approved by the Environmental Protection Agency (EPA). You can also eliminate standing water to prevent mosquitoes from breeding. The CDC currently recommends that pregnant women avoid travel to countries where Zika virus has been detected, and use protection during each sexual encounter with a male partner who has recently been in a country where Zika virus is present.

You can stay up to date on the situation with Zika virus by visiting these websites:

• Centers for Disease Control and Prevention (CDC)
• World Health Organization (WHO)

This information is available to view and/or download in PDF form [PDF, 661 KB].

Update