Stelberto Soares, a municipal engineer who has worked on Rio sanitation issues for decades, said that the government’s efforts to clean the waters were superficial at best.

“They can try to block big items like sofas and dead bodies, but these rivers are pure sludge,” he said, “so the bacteria and viruses are going to just pass through.”

“We just have to keep our mouths closed,” said 24-year-old Afrodite Zegers of the Dutch sailing team – one of the 10,000 athletes from 205 countries competing in Brazil.

Scientists and researchers found a wide array of disease-causing viruses and bacteria that can cause ailments such as diarrhea, vomiting, and death in people will poor immune systems.