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Why Zika risk is low for Olympic athletes in Rio

The Nilton Santos stadium in Rio, one of several Olympic venues.

Some health professionals have lobbied to postpone the upcoming Rio de Janeiro Olympics due to the risk of the Zika virus, which is spread by mosquitos and – less commonly – through sexual intercourse. Other experts disagree that Zika poses a significant enough threat to warrant changing the venue or date of the games, set for August 5 to August 21.

“The risk of Zika infection in Rio during the Olympics is very low,” says Uriel Kitron, chair of Emory’s Department of Environmental Sciences and an expert on mosquito-borne diseases. “But if you are pregnant, or are thinking of getting pregnant right now as part of a couple, then you may want to consider even this low risk of transmission, given the potential serious complications.”

He refers travelers to the current advisory of the Centers for Disease Control and Prevention. The CDC advises women who are pregnant “to consider not going to the Olympics,” due to the link between Zika infections and severe birth defects. The CDC also recommends special precautions for men and women to practice safe sex following any possible exposure to the Zika virus.

When Zika popped up in Brazil last year, Kitron already had ongoing research projects in the country focused on how urban mosquitos spread the viruses of dengue and chikungunga. The population had no immunity to Zika and the virus swept like wildfire through the country. Kitron and his Brazilian colleagues quickly expanded their research to include cases of Zika, which can cause a rash and relatively mild illness, although most of those infected have no symptoms at all. It was not until months later that the more insidious effects of the Zika virus became apparent.

Kitron and his colleagues completed one of the first epidemiological studies, now out in Emerging Infectious Diseases, showing the strong link between the epidemic curve of the outbreak and a spike in cases of Guillain-Barré syndrome and babies born with smaller than normal heads, a condition known as microcephaly.

In the following interview, Kitron discusses some of what is now known about this emerging infectious disease and why mosquito surveillance and control is currently the key to containing its spread.

Why do you think the risk is low for Zika virus transmission during the Olympics?

For one thing, August is the winter season in Rio, when mosquito populations are at their lowest. And the areas where the athletes will be staying and competing are well-maintained, making Olympic visitors even less likely to encounter a mosquito.

The rates of Zika infection in Brazil have gone down drastically since last year, probably because the population now has herd immunity, so that further lowers the risk of transmission. Brazil is no longer the “hot spot” of the Zika pandemic. The horse has already left the barn as Zika has moved throughout Latin America and the Caribbean.

The U.S. territory of Puerto Rico, where an outbreak began more recently, currently has high rates of new Zika infections and summer is the high season for transmission.

Read Full Interview in eScienceCommons »

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