Athletes competing in next year's 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 AP investigation has found. An AP analysis of water quality 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. Highlights from the extensive AP investigation: