Zika fears prompted dozens of athletes, including golfer Rory McIlroy and basketball player Stephen Curry, to pull out of the Rio Olympics.
The fears persisted despite assurances that the danger of being infected had been greatly reduced because the Olympics were taking place during Brazil's winter.
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The ongoing Zika outbreak was first detected last year in Brazil, where it has been linked to more than 1,700 cases of microcephaly - a birth defect marked by small head size - in babies of infected mothers.
There is no vaccine for Zika, which usually only causes mild flu-like symptoms in those infected.
The athletes are not leaving anything to chance.
The South Korean Olympic squad unveiled uniforms that cover them from neck to toe. The Australian athletes were provided with "Zika-free" condoms.
"We take mosquito repellent and we're sensible in daytime with what we wear," Hanna Melonz, a British sailing athlete, told Al Jazeera.
"We also don't plan on getting pregnant very quickly."
Source: Al Jazeera and agencies