Super hot, super windy, super wavy. Those are the kinds of “supers” Olympic sailors and windsurfers generally have to prepare for. But there’s apparently a new challenge in Rio’s Guanabara Bay and Carioca River, where some athletes will compete in the 2016 Summer Olympics — super bacteria. And yep, it’s the kind that can kill you. Per the Associated Press:

The Instituto Oswaldo Cruz, Brazil’s most respected health research institute, said it has discovered bacteria that produce an enzyme that make it resistant to most forms of treatment in water samples taken from various spots along the Carioca River. Among the spots is where the river flows into the city’s Guanabara Bay, site of the 2016 sailing and wind surfing events.

The enzyme in question is called the KPC enzyme, which gained notoriety in the United States in 2012 when it was found in 37 states, mostly in hospitals, where it had an estimated mortality rate of 50 percent in patients with suppressed immune systems.

“The illnesses caused by these microorganisms are the same as those caused by common bacteria, but they require stronger antibiotics and, sometimes, can require hospitalization,” the study’s coordinator, Ana Paula D’Alincourt Carvalho Assef, told the AP. “Since the super bacteria are resistant to the most modern medications, doctors need to rely on drugs that are rarely used because they are toxic to the organism.”

Surely, Olympic athletes, who for the most part, are robust, healthy and have strong immune systems are less at-risk, though, right?

Not so surely, actually, the Instituto says. There has yet to be a case of super bacteria infection from the contaminated waters the Instituto tested, but just because no one’s gotten sick doesn’t mean the super bug doesn’t pose a threat to the wider world.

“Carriers can take these resistant bacteria back to their own environments and to other people, resulting in a cycle of dissemination,” the Instituto said, speaking of people who may have gotten contaminated but not have succumb to illness.

This was not how it was supposed to be. As part of its Olympic bid, Rio had promised to reduce pollution in the Guanabara Bay, which has become a receptacle for some of the city of 12 million’s untreated sewage, by 80 percent, the BBC reports. In June, however, Rio Mayor Eduardo Paes said that goal would not be met.

The state of the bay is a disappointment to many sailing teams, including the U.S. contingent.

“Our job is to prepare our athletes and we encourage all clean-up efforts on Guanabara Bay,” Josh Adams, Managing Director of U.S. Olympic sailing told The Washington Post. Adams says the organization is taking the new findings seriously and will compare them to their own water sample test findings, which the team’s medical staff took earlier this year.

“We are going to follow what the experts recommend,” Adams said, referring to the U.S. medical team’s analysis, which is ongoing. He was quick to add, however, that the Instituto’s findings will not immediately affect the training regimen of U.S. Sailing Team Sperry Top-Sider, which has 14 athletes racing in Guanabara Bay this week.

“We are preparing to race the Olympic games at this venue and don’t expect it to change,” he said.