Catching Zika at Olympics Unlikely, Study Finds

     (CN) — Less than two weeks before the Summer Olympics kick off in Rio de Janeiro, Brazil, new research indicates that the threat of the Zika virus to fans and athletes may not be as severe as feared.
     The host nation has been severely affected by the spread of the virus, which has been intensified domestically by a severe recession and political turmoil.
     While Zika is primarily transmitted through mosquito bites, the virus can also be transmitted sexually. Zika’s connection to microcephaly, a congenital disorder that leads to reduced head size and potential brain damage in fetuses, makes the virus particularly dangerous for pregnant women.
     Two separate studies analyzing the risk associated with Zika transmission in Brazil were published.
     In the first study, published in the Annals of Internal Medicine, Yale scientists researched and modeled the risk for Olympics attendees, determining that there was only a small chance they would contract the virus.
     The volume of people traveling to the games in Rio presents straightforward health and safety concerns, with nearly 500,000 visitors projected. Butespite the estimated number of attendees, the researchers found that just three to 37 visitors will contract the virus and bring it home.
     “Our calculation provides worst-case estimates of travel-associated Zika risk by assuming that visitors encounter the same infectious exposures as local residents. Under these pessimistic conditions, we estimate that an individual traveler’s probability of acquiring infection in Rio de Janeiro ranges from 1 in 56,300 to 1 in 6,200,” the report says.
     Their findings are based on a model that compared the spread of Aedes aegypti mosquitoes — the primary vector of Zika — and the spread of the dengue virus during the 2014 World Cup, also in Brazil.
     The researchers noted that many travelers are coming from nations where the virus is already spreading.
     “The possibility that travelers returning from the Olympics may spread Zika has become a polemic issue that has led to athletes dropping out of the event and, without evidence, undue stigmatization of Brazil. This study provides data, which together with initial findings from Brazilian scientists, show that these concerns may be largely exaggerated,” Albert Ko, co-director of the Yale Global Health Justice Partnership, said in a statement.
     The Olympic Games begin Aug. 5.
     A second study published in the journal Nature Microbiology used model-based projections to pinpoint how many childbearing women have either contracted Zika or will by the end of the current outbreak.
     The researchers determined that up to 1.65 million childbearing women could be infected by the end of the “first wave of the epidemic.” Their figure is substantially lower than previous estimates, which did not take into account herd immunity or socio-economic factors, according to the researchers.
     “Projections such as these have an important role to play in the early stages of an epidemic, when planning for surveillance and outbreak response is actively under way both internationally and locally,” the study says.
     The researchers did not estimate how many infected women might give birth to children with microcephaly.

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