Athletes competing in the upcoming Summer Olympics in Rio de Janeiro will be swimming and boating in waters so contaminated with human feces that they risk becoming violently ill and unable to compete in the games, an investigation has found

An analysis of water quality has revealed dangerously high levels of viruses and bacteria from human sewage in Olympic and Paralympic venues — results that alarmed international experts and dismayed competitors training in Rio, some of whom have already fallen ill with fevers, vomiting, and diarrhea. It is the first independent comprehensive testing for both viruses and bacteria at the Olympic sites. Brazilian officials have assured that the water will be safe for the Olympic athletes. But the government does not test for viruses. Disease-causing viruses in some tests measured up to 1.7 million times what would be considered hazardous on a Southern California beach. Prime beaches are deserted because the surf is thick with putrid sludge, and periodic die-offs leave the Olympic lake, Rodrigo de Freitas, littered with rotting fish. The viral testing found not one water venue safe for swimming or boating. Rodrigo de Freitas Lake was thought be safe, yet its waters were among the most polluted for Olympic sites, with results ranging from 14 million adenoviruses per liter on the low end to 1.7 billion per liter at the high end. Austria's sailing coach has lost training days after sailors fall ill despite extreme precautions. "The Olympic medal is something that you live your life for," he says, "and it can really happen that just a few days before you get ill and you're not able to perform at all." A US expert in waterborne viruses conducted a "conservative" risk assessment, assuming that athletes would ingest three teaspoons of water — far less than athletes say they take in. She found "an infection risk of 99%." Nearly 1,400 of the expected 10,000 Olympic athletes participate in water sports. In 75% of the samples at the Olympic lake, fecal coliforms exceeded Brazil's legal limit for "secondary contact" — in two samples spiking to over 10 times the accepted level. Brazil promised to build eight treatment facilities to filter much of the sewage and household trash. Only one has been built. "Brazilian authorities promised the moon in order to win their Olympic bid and as usual they're not making good on those promises," says a biologist. Rio Gov. Luiz Fernando Pezao has acknowledged "there's not going to be time" to finish the cleanup of the bay.