• Wed. Jun 29th, 2022
Zika virus

Zika virus is often transmitted to humans by mosquito bites, primarily in tropical and subtropical regions of the world. Most people infected with the Zika virus have no signs. Some people have a mild fever, rash, and muscle aches. In rare cases, the Zika virus can cause brain or nervous system problems, such as Guilin-Barre syndrome, even in those who show no signs of infection. Infections caused by the Zika virus are also known as Zika, Zika fever, or Zika virus infection.

Women infected with the Zika virus during pregnancy have a higher risk of miscarriage. Zika virus infection during pregnancy also increases the risk of severe birth defects in children, including a dangerous brain condition called microcephaly.

Researchers are working to find a vaccine for the Zika virus. For now, the best way to prevent infection is to avoid mosquito bites and reduce mosquito habitat.


As many as 4 out of 5 people infected with the Zika virus have no signs. When symptoms do appears, they usually begin two to 14 days after a person is bitten by an infected mosquito. Symptoms commonly last about a week, and most people recover fully.

Symptoms of the Zika virus most generally include:

  • Rash
  • Mild fever
  • Joint pain, particularly in the hands or feet
  • Red eyes (conjunctivitis)

Other symptoms may include:

  • Abdominal pain
  • Muscle pain
  • Headache
  • Eye pain
  • Fatigue or a general feeling of discomfort


Zika virus is often spread from person to person through the bite of an infected person. The mosquitoes known to carry the virus include two Aedes mosquitoes, which are found worldwide.

When a mosquito bites someone who is already infected with the Zika virus, the virus attacks the mosquito. Later, when an infected mosquito bites another person, the virus enters the person’s bloodstream and causes infection.

During pregnancy, the Zika virus is transmitted from mother to fetus. 

The virus is spread through sexual contact and from one person to another. In some cases, people get the virus through blood transfusions or organ donations.

Risk factors

High-risk factors for Zika virus infection include:

  • Living or traveling in countries where there have been outbreaks. Being in tropical and subtropical regions increases the risk of contracting the Zika virus. Particularly high-risk areas include the Pacific Islands, several countries in Central, South, and North America, and islands near West Africa. As mosquitoes carrying the Zika virus are found around the world, outbreaks may continue to spread to new areas.
  • Most Zika virus infections have been reported in the United States by travelers returning to the United States from other areas. But the mosquitoes that carry the Zika virus live in some parts of the United States and its regions. Florida, Texas, U.S. Local outbreaks have been reported in the Virgin Islands and Puerto Rico.
  • Having unprotected sex. Zika virus is spread from one person to another through sexual contact. Zika virus can increase the risk of infection for up to three months after unprotected sexual intercourse. For this reason, pregnant women who have recently resided in the area where the Zika virus is common or who have traveled should use a condom during sexual activity or abstain from sexual intercourse until the baby is born. All other couples can reduce the risk of sexual transmission by using a condom or by avoiding sexual activity for up to three months after the trip.


Women who are infected with the Zika virus during pregnancy have an increased risk of miscarriage, preterm birth, and stillbirth. Zika virus infection during pregnancy also increases the risk of serious birth defects in infants (congenital Zika syndrome), including:

  • A much smaller than the normal brain and head size (microcephaly), with a partly collapsed skull
  • Brain damage and reduced brain tissue
  • Eye damage
  • Joint problems, including limited motion
  • Reduced body movement due to too much muscle tone after birth

In adults, infection with the Zika virus may cause brain or nervous system complications, such as Guillain-Barre syndrome, even in people who never show symptoms of infection.

When to see a doctor

See your doctor if you think you or a family member may have the Zika virus, especially if you have recently traveled to an infected area. The U.S. Centers for Disease Control and Prevention (CDC) has blood tests to detect the Zika virus and other viruses transmitted by mosquitoes.

If you have been pregnant and have recently traveled to an area where the Zika virus is common, ask your doctor if you should be tested, even if there are no symptoms.