RIO DE JANEIRO — Mexico sailing coach Agustin Bellocchio offered a tip to sailors and windsurfers at this week's Olympic test event in Rio de Janeiro's polluted Guanabara Bay: Don't swallow the water.

"Shut your mouth when you're in the bay, and don't take in any water," said Bellocchio, an Argentine working for Mexico. "Everyone knows this bay is badly contaminated."

Much of the focus at the recent test events for sailing and rowing has been on having limited contact with the water. Amid reports of high pollution in Rio's waters, athletes are getting advice from team doctors and their federations about precautions to avoid becoming ill.

How hard is that? To get an idea, picture golfers not touching grass with their hands. Or figure skaters fearful of taking ill from a fall on the ice.

"It's not normally such a consideration at any other events, but clearly it's a consideration here," said Peter Conde, the performance director for the Australian sailing team.

Conde said Australia has installed hand sanitizers on the coach boats, the dinghies that coaches ride.

"We need to clean our hands after we've handled ropes, or touched the water or anything of that nature," Conde said.

Asked if this was standard practice, Conde replied: "Definitely not."

Polish windsurfer Malgorzata Bialecka said she took a spill into the bay the other day and said "the water doesn't smell good."

"I had to swim in this water and it wasn't nice," she said. "And I was a little bit afraid after that."

Rio's pollution has been in the spotlight since an independent five-month analysis by The Associated Press published July 30 showed dangerously high levels of viruses from human sewage at all Rio Olympic water venues.

Under growing pressure, Rio state officials are employing stop-gap measures to retrieve floating rubbish from the bay, track detritus from helicopters, and step up bacteria-only monitoring. The IOC has declined to endorse testing for viruses, which can cause stomach and respiratory ailments that could knock an athlete out of competition.

Local organizers and the International Olympic Committee have rejected moving rowing and sailing to cleaner venues.

Rowers in a test event a week ago in Rodrigo de Freitas Lagoon sterilized their oars with bleach, sealed water bottles in plastic zip-top bags, and carried antiseptic mouthwash.

"I don't think in this lake they'll be throwing the coxswain into the water," quipped Swiss rower Katharina Strahl.

Dr. Nebojsa Nikolic, the top medical official of the International Sailing Federation, met over the weekend with team doctors to remind about basic hygiene, shots for hepatitis A and typhoid and other preventative measures.

"Frankly, sailors are thinking about how to win the medals, not how to not get infected," Nikolic said.

Sailors in Rio are encouraged to shower or hose off after leaving the water, a common practice in sailing events. Dr. Nikolic recounted seeing some grab water bottles with wet hands soaked in polluted bay water.

"Sailors come back and they are thinking about hydration," he said. "They start on the boat, and they don't think to clean themselves. So if someone immediately drinks from the bottle with soiled hands, you have the risk of transporting disease."

A bout of diarrhea could sideline an athlete for several days, jeopardizing any chance at an Olympic medal.

The Americans seem among the hardest hit with illnesses, although it's difficult to connect falling ill directly to the polluted water.

"Our team had a few isolated incidents of a fast-moving bug which impacted a few of our athletes," said Josh Adams, managing director of U.S. Olympic Sailing.

Adams said 15 American athletes were in Rio, but declined to give a specific number who fell ill.

At least a dozen American athletes, in a squad of 40, fell ill at the rowing test. An American team physician speculated it was the water, but test-event officials attributed it to "travel diarrhea."

"We're well aware of the concerns over the water," Adams said.

Many teams have trained for years in Rio, hoping to build immunity. Several have done water-quality tests. And over the weekend, dozens of sailors watched as a brown substance poured into the bay, just a few meters (feet) away from a boat launching ramp.

Olympic gold-medalist Nathan Outteridge told The Australian newspaper of sailing through sewage flowing into the bay to reach the race course.

"You just don't want to have to be dealing with stuff like that," he said.