One expert's advice for swimmers at the Rio Olympics? 'Don't put your head underwater.'

Swimmers at the Rio Olympics might have a hard time following one expert's advice on how to avoid getting "violently ill" during the festivities in Brazil. After a study revealed alarmingly high levels of viral contamination in Rio's waters, Valerie Harwood, chair of the Department of Integrative Biology at the University of South Florida, is offering this warning to Rio athletes and tourists: "Don't put your head underwater."

The advice followed the release of the final results of a 16-month-long study commissioned by The Associated Press, which revealed "viral levels at up to 1.7 million times what would be considered worrisome in the United States or Europe." "Seeing that level of human pathogenic virus is pretty much unheard of in surface waters in the U.S.," Harwood told AP. "You would never, ever see these levels because we treat our waste water."

With contamination that high, The Associated Press reported a mere three teaspoons of water can "cause stomach and respiratory illnesses and more rarely heart and brain inflammation."

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More than 1,000 athletes are set to compete in water events at the Rio Olympics, which kick off Friday, Aug. 5. Head over to The Associated Press for more on the story.