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Infectious Diseases

The Zika Virus

A biting Aedes aegypti mosquito, which is responsible for transmitting Zika virus.
Photo Courtesy of: James Gathany, Centers for Disease Control and Prevention

NIH launches multiple research efforts to understand the Zika virus and find a vaccine.

Zika virus is a member of the flavivirus family. Other flaviviruses include dengue, yellow fever, and West Nile virus. Like its relatives, Zika virus is primarily transmitted to humans through the bite of infected Aedes aegypti mosquitoes.

It may also be transmitted from an infected pregnant woman to her baby during pregnancy or around the time of birth. Spread of the Zika virus through blood transfusion and sexual contact has been reported. Most people who become infected with Zika virus do not become sick. For the 20 percent of people who do become sick, the illness is generally mild with symptoms that include fever, rash, joint pain, or conjunctivitis (red eyes) and lasts several days to a week.


There have been reports of a serious birth defect of the brain called microcephaly among babies born to infected women. Microcephaly is a condition in which a baby's head is abnormally small and can be associated with incomplete brain development. Currently, it is unclear what link, if any, Zika infection may have to microcephaly. International research organizations are investigating.

There have also been reports of Guillain-Barré syndrome (GBS) in some countries where Zika transmission is occurring. GBS is a rare autoimmune disorder in which damaged nerve cells cause muscle weakness and, sometimes, paralysis. Most people recover from GBS, but some have permanent damage and in rare cases GBS can lead to death.

Anthony S. Fauci, MD, Director of the National Institute of Allergy and Infectious Diseases.
Photo Courtesy of NIH

"You could have a Zika virus vaccine in large-scale clinical trials in 2017, which is rocket speed for a vaccine."

NIAID Zika Virus Research

The National Institute of Allergy and Infectious Diseases (NIAID) at NIH is accelerating research in areas such as:

  • The natural history of the Zika virus
  • Basic research on how it causes disease
  • Diagnostics to rapidly determine if someone is or has been infected with Zika
  • How to distinguish it from other flaviviruses
  • Development of treatments and vaccines

Although Zika virus is new to the Western Hemisphere, NIAID scientists and grantees have long studied Zika relatives, such as dengue and West Nile virus. Those studies provide a springboard to accelerate investigations of Zika and may yield approaches to developing therapeutics and vaccines that will combat Zika virus.

NIAID is working with its partners in government, academia, and the pharmaceutical and biotechnology industries to better understand Zika virus, the disease it causes, and ways to combat it.

It is possible that an investigational Zika vaccine will be ready to enter early-stage human trials in 2016. An early-stage trial would examine whether an experimental vaccine is safe and generates immune responses in vaccinated volunteers.

"You could have a Zika virus vaccine in large-scale clinical trials in 2017, which is rocket speed for a vaccine," said NIAID Director Dr. Anthony S. Fauci.

Find Out More

Spring 2016 Issue: Volume 11 Number 1 Page 14-15