A strain of drug-resistant bacteria normally found in hospitals has recently been discovered in the waters where the 2016 Olympic sailing and wind surfing events will be held in Rio de Janeiro. Klebsiella pneumoniae carbapenemase (KPC) contains an enzyme which makes it resistant to most antibiotics; many who come into contact with the bacteria could become carriers even if they don’t experience symptoms of illness.

Researchers at the Instituto Oswaldo Cruz in Brazil found the “superbug” in three out of five samples taken from along the course of the Carioca River, which flows into the city’s Guanabara Bay where the sailing and wind surfing events will be held. No reported infections due to the contaminated water have been reported, but swimmers have been alerted to the possible danger. The bacteria was first detected in the water at the point where the river passes through areas with homes and hospitals; no bacteria was detected at the headwaters.

Approximately 70% of the sewage from Rio de Janeiro goes untreated and flows into rivers, onto beaches, and into the Guanabara Bay; Olympic organizers pledged to reduce 80% of the sewage and garbage deposited into the water, but state that they will be exploring the findings before responding to this study.