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(A-Z listing includes diseases, conditions, tests and procedures)

Zika Virus

Zika Virus: What You Need to Know

  • The Zika virus spreads to humans, primarily from infected Aedes aegypti mosquitos.
  • Zika was first identified in Uganda in 1947 but was not reported in the Americas until early 2015. It is now spreading throughout the Americas.
  • Pregnant women who contract this virus have experienced a much higher rate of birth defects than normally reported, including microcephaly and other neurologic abnormalities.
  • Symptoms of Zika are similar to dengue fever, chikungunya virus and West Nile virus, and include fever, rash and joint pain. Many pregnant women may not exhibit symptoms, even if their fetus has been affected.
  • There is no vaccine or treatment for Zika virus.

What is the Zika virus?

Zika is a mosquito-borne virus, similar to dengue fever, yellow fever or West Nile virus. The virus is predominantly transmitted by infected Aedes aegypti mosquitos, which are found throughout the Americas. Transmission can also occur by intrauterine infection — if a mother is bitten by an infected mosquito and becomes infected, Zika can cross the placenta, affecting the fetus. Reports have also documented transmission at the time of delivery.

There have been some cases of sexual transmission and contraction through blood transfusion or laboratory exposure. These transmissions are thought to only be possible during the incubation period, which is approximately three to 12 days.

While anyone can contract Zika, the impact of the virus has most significantly been seen in pregnant women and their fetuses. Zika during pregnancy has been associated with microcephaly — a condition in which an infant’s head is substantially smaller than expected, leading to developmental issues — and other neurologic abnormalities.

What You Need to Know About Zika Virus

Mosquito sucking blood

At Johns Hopkins Medicine, we are actively examining the ongoing spread of Zika virus in order to ensure the well-being of our patients and employees. On this comprehensive site, you can find facts about the virus and microcephaly, as well as precautions you can take and information about our ongoing research.

Learn more.

What are the symptoms of Zika?

These are the most common symptoms of the Zika virus:

  • Fever

  • Maculopapular rash

  • Arthralgia (joint pain)

  • Conjunctivitis

  • Headache

Only about one in five infected individuals will exhibit symptoms, and they will be mostly mild. Symptoms will usually last several days to a week. It is rare to require hospitalization for the Zika infection.

How is Zika diagnosed?

If you are not pregnant and exhibit Zika symptoms, your physician will perform a blood test for evidence of Zika virus infection.

If you are pregnant and have traveled to a Zika-affected country, your physician will perform a blood test, even if you are not exhibiting any symptoms. You will also have at least one ultrasound to evaluate your fetus for infection.

Facts About Zika Virus

In this informative video, a Johns Hopkins expert discusses information about the spread of Zika virus, related health concerns and the current state of vaccine development.

How is Zika treated?

Antiviral treatment is being investigated, but there is currently no vaccine or medication available to prevent or treat Zika infection. If you are exhibiting symptoms, get plenty of rest and drink fluids to prevent dehydration. You may use acetaminophen for fever. If you are pregnant, you will continue to undergo regular monitoring by your maternal-fetal medicine specialist to watch for fetal abnormalities after your symptoms have passed.

Who is at risk for Zika?

Women who are planning to become pregnant or are currently pregnant are at the greatest risk for the Zika virus if traveling to an area with ongoing outbreaks. While it is unknown if pregnancy itself increases a woman’s vulnerability to the virus, Zika can cross the placenta and affect the fetus. There has been a high rate of birth defects seen among babies whose mothers came in contact with Zika during pregnancy.

More Information About Zika Virus from Johns Hopkins Medicine

Pregnant woman

Zika Virus: Answers from Maternal-Fetal Medicine Specialist Jeanne Sheffield

As the Zika virus becomes more prominent throughout the Americas, awareness efforts are increasing for expectant mothers. In this article, learn how Zika can be contracted, how the virus affects pregnant women in particular and what preventive measures are available.

Read more.

How can Zika be prevented?

The best way to prevent Zika is to avoid exposure. Pregnant women should delay traveling to areas where Zika outbreaks are ongoing. Women who are considering pregnancy should speak with their obstetrician-gynecologists about prospective travel to areas with Zika outbreaks. The Centers for Disease Control and Prevention keeps an updated list of affected countries.

If you have to travel to areas where Zika has been reported, take precautions to avoid mosquito bites:

  • Use Environmental Protection Agency-approved insect repellent and follow the product label. Pregnant women can safely use these approved repellents.

  • Cover any exposed skin if you have to go outside.

  • Stay in air-conditioned and screened-in areas.

Additionally, if a man travels to an area of active Zika virus infection and has a pregnant partner, they should abstain from sexual activity or consistently and correctly use condoms during sex for the duration of the pregnancy.

If you are pregnant and have traveled to a country where Zika virus cases have been reported, please contact your health care provider as soon as possible.

#TomorrowsDiscoveries: Exploiting the Weakness of Mosquitoes | Christopher Potter, Ph.D.

Neuroscientist Christopher Potter and his team understand that mosquitoes pass on a disease through a simple bite. They are working to understand how an insect’s brain interprets and responds to odors. This will allow them to find better methods to stop the spread of diseases, such as malaria and Zika virus.

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