10 Essential Facts About the Zika Virus

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If you’ve heard about the Zika virus and are wondering what it is, you’re not alone. Clusters of Zika-related birth defects are an international public health emergency, according to the World Health Organization (WHO). And WHO Director-General Margaret Chan, MD, characterizes the situation as an “extraordinary event and a public health threat to other parts of the world.”

A Honduran woman who gave birth to a baby girl with microcephaly in Hackensack, New Jersey, on May 31, was believed to have been infected with Zika in her home country, according to her doctors. And a baby born with microcephaly in January in Oahu, Hawaii, had also been infected with Zika. The child’s mother had previously lived in Brazil — a Zika hot zone with up to 1.3 million cases of infection.

The first Zika-related U.S. death was reported on April 29 in Puerto Rico; the cause was complications from Zika infection, including internal bleeding. Cases of this emerging infectious disease are soaring in the Americas and “spreading explosively,” says WHO’s Dr. Chan, and U.S. travelers are bringing the infection back with them.

Although usually spread by mosquitoes, the Zika virus is also transmitted through sex. The first U.S. case of sexual transmission was confirmed in Texas in early February, and the Centers for Disease Control and Prevention (CDC) has reported 10 more, with other cases being investigated.

For most people, the Zika virus causes only a brief, mild flu-like illness. But new research points to a possible connection to higher rates of Guillain-Barré syndrome in adults, a condition in which the immune system attacks nerves following an infection, causing muscle weakness and paralysis. In pregnant women, the virus can cause birth defects, including microcephaly — an abnormally small head and brain size.


In January, the CDC posted a travel alert advising pregnant women to delay travel to areas where Zika is active. The travel alert list continues to expand and now includes 48 countries or territories in the Americas, the Pacific Islands, and Africa.

The CDC guidelines recommend that pregnant women coming back from these areas get tested for Zika, and that men who have a pregnant partner use condoms if they live in or travel to areas with Zika infection. As of May 26, the Zika Pregnancy Registry notes 206 U.S. cases of Zika in pregnant women, and an additional 166 in U.S. territories, according to the CDC.

With the 2016 summer Olympic Games coming up in Rio de Janeiro, public health experts are worried that the virus may spread far beyond Latin America. The World Health Organization expects Zika to spread to all but two countries in the Americas: Canada and Chile. Athletes who are concerned about Zika should consider skipping the games, the U.S. Olympic Committee now says.

Given the link to birth defects, preventing the spread of Zika is critical, especially for women in their childbearing years.

Here are the facts about the Zika virus:

1. The Zika virus is spread by mosquito bites and by sex. Zika is an RNA virus related to the West Nile, yellow fever, and dengue viruses, and passed on by the bite an infected Aedes mosquito. “A person bitten by a mosquito that has the virus then becomes viremic. They get bitten by another mosquito, which then passes the virus along,” explains Peter Jay Hotez, MD, PhD, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston.

The Zika virus is also sexually transmitted by men infected with Zika to both female and male partners. If your male partner has or had Zika, or traveled to an area where Zika is spreading, condom use is advised for at least six months.

The CDC recommends that if you’re pregnant and your partner had or has Zika, or has been exposed to mosquitoes in regions that have Zika, you should speak with your doctor and also consider using condoms or abstaining from sex throughout pregnancy.

As a safety measure to protect the blood supply and transplant recipients from Zika, the FDA recommends not donating blood, tissue, or organs if, within the last six months, you’ve:

  • Been diagnosed with the Zika virus
  • Been in an area with active Zika virus
  • Had sex with a man who’s had the virus

Banned donations include blood, organs, semen, oocytes, umbilical cord blood, placenta, corneas, bone, skin, and heart valves. Deceased organ or tissue donors are also no longer eligible if they had been diagnosed with Zika within six months of their death.