Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention


A Zika infection is caused by a virus that is usually passed from an infected mosquito.

The virus may cause flu-like symptoms in some but has little effect on most people.

The virus can cause significant birth defects to developing fetuses. More studies are needed to determine the exact reason but national organizations have issued some safety guidelines.

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A specific type of mosquito can pick up the Zika virus when it bites someone with a current infection. The mosquito can then pass the virus to the next person it bites.

Though most infections pass from mosquito to person, some infection may pass from person to person:

  • The virus may pass during sexual intercourse with a Zika infected man, whether or not he has symptoms.
  • The virus can pass to a fetus if the woman was infected with Zika during or just before pregnancy.

Risk Factors

The greatest risk factor is spending time in a high-risk area without proper mosquito protection. A current outbreak of Zika has been reported in:

  • South America, particularly Brazil; Colombia, Bolivia, Ecuador, French Guiana, Guatemala, Guyana, Paraguay, Suriname, and Venezuela
  • Mexico and Central America, particularly El Salvador; Honduras, and Panama
  • The Caribbean, particularly Barbados, Dominican Republic, Guadeloupe, Haiti, Martinique, Puerto Rico, and Saint Martin
  • Southeast Asia and the Pacific Islands

Previous outbreaks have been reported in Africa. Check with government travel resources to see where current outbreaks are before you travel.


If symptoms develop, they may appear a few days after the bite. Symptoms may last a few days to a week and can include:

  • Fever
  • Rash
  • Conjunctivitis—redness and irritation of the eye
  • Headache
  • Joint pain
  • Muscle pain

Zika infection in pregnant women may cause certain complications for the baby, such as:

  • Microcephaly—a small head due to underdevelopment of the brain
  • Fetal brain defects
  • Eye defects
  • Hearing loss
  • Impaired growth
  • Spasticity and seizures
  • Abnormal joints
  • High muscle tone


You will be asked about your symptoms and medical history. A physical exam will be done. Talk to your doctor about any recent travel, especially to high-risk places. Your doctor may suspect a Zika infection based on your symptoms and travel history.

A blood test is needed to confirm Zika. Since Zika passes on its own in a few days, the blood test not done routinely in pregnant women.

If you are at risk due to travel to high-risk area or sexual exposure:

  • You should be tested if you have symptoms of Zika or if an ultrasound shows that your fetus has abnormalities that might be related to Zika infection.
  • You may be offered testing if you have other risk factors

If you live in or frequently travel to high-risk areas:

  • You should be tested if you have symptoms of Zika.
  • You may be offered testingat your first prenatal care visit, followed by two additional rounds of testing at regular prenatal care visits during your pregnancy.

If the test is positive for Zika and you are pregnant, you may be referred to a maternal-fetal specialist or an infectious disease specialist with expertise in pregnancy.

If you are planning to become pregnant and have traveled or live in high-risk places, talk to your doctor about whether you or your partner should be tested for Zika virus.


There are no medications to treat a Zika infection. If symptoms appear, they should pass on their own within a week. Basic home care, including rest and drinking enough fluids, can help with recovery.

Acetaminophen may be advised to help decrease fever or pain. Other over the counter medications, like nonsteroidal anti-inflammatory drugs (NSAIDs), are not advised if the specific virus has not been identified. NSAIDs and aspirin can cause complications with other mosquito-borne illnesses, such as dengue infection.

If you have the Zika virus, it can be passed directly to other people through sexual contact. If a mosquito bites you while you are infected, that mosquito can then pass the infection to someone else. The mosquito will most often affect people nearby, such as family members or neighbors. It is important to take precautions against mosquito bites while you are infected, for about a week, to prevent the spread of the virus.

Family Planning

The Zika virus may exist in the body or in sperm for a short time even after symptoms have passed. To decrease the risk of passing the virus to a new fetus the US Center for Disease Control (CDC) recommends:

  • Women who have been infected or suspect an infection should wait at least 8 weeks before trying to get pregnant.
  • Men who have been infected or had possible exposure to Zika should wait at least 6 months before trying for pregnancy.


There are some recommended precautions for women who are pregnant.

  • Pregnant women who live in areas without Zika should:
    • Delay travel to any area where Zika virus is spreading.
    • If travel is unavoidable, pregnant women should closely follow mosquito precautions. Travel advisories are available from the Centers for Disease Control and Prevention or the World Health Organization.
    • Use a condom during sex or abstain from sex with a male partner who has lived in or traveled to an area with Zika.
    • See a doctor or healthcare provider.
  • Pregnant women who live in areas with Zika should:
    • Closely follow mosquito precautions.
    • Use a condom during sex or abstain from sex with a male partner who has lived in or traveled to an area with Zika.
    • See a doctor or healthcare provider.