Things You Need to Know About Zika Virus

First published February 2016
Updated November 2025

Zika is a viral infection that is spread mostly by mosquito bites in tropical and near-tropical parts of the world. It causes mild to severe illness; most who are infected recover completely.

How is Zika spread?

The Zika virus is mostly spread by mosquito bites. Sometimes Zika can also be spread from person to person via intercourse, or to fetuses if their carrier is infected while pregnant. It is rarely spread through blood transfusions or tissue donations from a person with a recent infection. It cannot be spread through coughing, sneezing, kissing, food, or water.

Where is Zika found?

The Zika virus was first discovered in 1947 in Uganda. For many years, Zika outbreaks were mostly small and confined to Africa and Asia; however, in the early 2000s the virus began to cause larger outbreaks, and in the 2010s it spread to the Americas for the first time.

The mosquito that spreads Zika has been found on 6 of the 7 continents (all except Antarctica), mostly in countries in and around the tropics. The mosquitos’ range has expanded over recent years, so it may spread to new areas in the future. For example, although the United States and Europe are not considered typical “Zika areas,” cases were identified in the Texas and Florida (in 2016) and in France (in 2019), reflecting changes in weather patterns and mosquito habitats.

What are the symptoms of Zika virus infection?

Most people with Zika virus infection have no or mild symptoms. If a person does get sick, they usually start to feel ill about one week (and no more than two weeks) after infection, and may report fever, red eyes, itchy skin rash, headache, and joint/muscle pain. Sometimes they have arm and leg swelling, or swollen lymph nodes. Symptoms can last for only a couple of days up to one week.

It is unusual to get severely sick from Zika. Most people don’t need to be admitted to the hospital, but rarely, people with Zika can develop abnormal blood clotting or inflammation of the nerves, eyes, or brain and spinal cord that needs closer monitoring.

Almost all people infected with Zika after birth recover fully and have no long-term health problems. A small percentage can develop Guillain-Barré syndrome (when the body’s immune system attacks its own nerve cells) after infection, which can cause weakness and sometimes paralysis that can last up to months. Even in this case, though, most people do eventually recover.

If a mother is infected with Zika while pregnant, it can cause severe birth defects in the baby, even if she has no symptoms. Birth defects due to Zika infection are seen in about 1 out of every 20 exposed babies and are more common if a mother is infected early in her pregnancy.

The birth defects seen with Zika infection during pregnancy can be serious or mild. In the most severe cases, children may have a very small brain (microcephaly), stiff muscles and joints, feeding problems, hearing loss, poor vision, and seizures. Some of these problems may be lifelong. Some children may initially appear well at birth but then develop health problems, so they need to be monitored closely by a doctor as they grow.

How is Zika treated?

Current treatment of Zika virus consists of managing symptoms with lots of rest, fluids, and an over-the-counter medicine like acetaminophen for management of fever or pain.

Until your doctor is sure that you have Zika, they may treat you like you have a dengue infection, because dengue (similar to Zika) can lead to severe swelling and bleeding if not managed carefully. Dengue requires special monitoring of your blood counts until the fever goes away, and non-steroidal anti-inflammatory drugs (NSAIDs) like aspirin, ibuprofen, or naproxen should be avoided until the doctor says that it is safe to use them.

If someone develops Guillain-Barré syndrome following Zika infection, they often need hospital monitoring and may be given an antibody treatment (intravenous immunoglobulin, or IVIG) to try to stop the inflammation. If they continue to be sick even after IVIG then other treatments may be given.

Children with birth defects due to Zika virus benefit from close follow up with their doctor and referral to eye doctors, ear doctors and therapists to help with feeding, speech, and movement.

How can Zika be prevented?

Because the mosquitoes that spread Zika are found in the U.S. during warm-weather months, it is important to take measures to prevent mosquito bites. Use screens on windows and doors, wear long-sleeved shirts and long pants outside, and apply DEET- or picaridin-containing insect repellants on exposed skin as directed. DEET and picaridin are safe for young children, but should be applied by an adult, avoiding the eyes, nose, mouth, and hands (where it can be accidentally eaten).

You can also consider treating clothing and gear with permethrin, which repels mosquitoes and ticks for up to 30 days and lasts through multiple washes. Permethrin does not have an odor and is safe even for use around babies. It should not be used directly on the skin.

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. Strictly follow steps to prevent mosquito bites during the first week of illness, to avoid passing it to others.

• Zika virus can be spread during sex by a person infected with Zika to his/her sex partners, so condom use is critical.
• Avoid donating blood for 4 months and tissue (like umbilical cord blood, placenta, eggs, or semen) for 6 months after Zika infection.

Learn more and keep up to date on Zika information by visiting the CDC website.