Avoid the mosquitoes.

Don’t drink the water.

In fact, you might not want to even put your toe in the ocean.

Those are some of the health issues facing Brazil as the 2016 Summer Olympics heads to the shores of Rio de Janeiro.

The concerns led a Canadian public health professor to write in the Harvard Public Health Review that the Olympics should be postponed or moved to another location until the outbreak of the Zika virus there is under control.

Health experts interviewed by Healthline said that proposal is an overreaction, but they say athletes and spectators traveling to Brazil should educate themselves about the health threats and take the proper precautions.

The World Health Organization (WHO), the International Olympic Committee (IOC), the U.S. Olympic Committee (USOC) and the U.S. Centers for Disease Control and Prevention (CDC) have all said the games should proceed.

“From what we know about what’s going on in Brazil, we feel they can prevent certain health risks,” said Tom Skinner, senior press officer at the CDC.

The health issues have prompted the CDC as well as the WHO and other organizations to post guidelines for people traveling to Brazil in August for the Olympics.

Read More: U.S. Warned to Brace for Zika Virus »

The Zika Threat

Brazil reports there have been more than 90,000 likely cases of Zika virus infections in their country since February.

The nation’s southeast region, where the Olympics will be held, has more than 35,000 of those cases.

As an illness, Zika is relatively mild for most people. There are flu-like symptoms for a week or so. There is no vaccine yet for the disease transmitted by the same mosquito that carries dengue and other illnesses.

The most serious health threat is to unborn children. Pregnant women who contract Zika can infect a fetus with the disease.

The infection in a developing brain can cause microcephaly in an unborn child. This can cause lifelong brain defects.

Brazilian officials say there are more than 4,900 confirmed or suspected cases of microcephaly related to the Zika virus in their country.

CDC officials say they are monitoring the cases of 279 pregnant women in the United States and Puerto Rico with possible Zika virus infections.

Experts told Healthline that the Zika virus was going to spread around the world with or without the Olympics.

“The Zika virus will move regardless,” said Dr. Dana Hawkinson, an infectious disease physician with the University of Kansas Hospital.

However, the big question is if the Brazil games will speed up that process.

Skinner said the CDC is studying models now to try to predict how much and how quickly Zika will spread after the games, where people from virtually every country in the world will congregate in a relatively small area where Zika has been rampant.

Skinner said in a country like the United States where thousands of people visit Brazil every month, the impact will probably be minimal.

“We don’t feel the additional travel because of the Olympics is going to produce any significant spread of Zika in the United States,” he said.

However, the problem could be more serious in other countries where citizens don’t usually travel to Brazil.

Pregnant women are being advised to avoid South America this year, but a visitor to the Olympic Games could return home with the virus and infect a woman carrying a child.

Hawkinson points out scientists know that Zika stays in the blood stream for about a week. However, they don’t know how long it remains in semen.

“The problem is you never know when you’re going to get pregnant,” he said.

Hawkinson and other health officials agree precautions should be taken, but they also note it will be winter in Brazil in August and mosquito activity is likely to be minimal.

Dr. George Rutherford, a professor in the school of medicine at the University of California, San Francisco, adds that the Olympics will be held near the ocean. That’s salty water where mosquitos don’t usually congregate.

He also points out that Brazil is in the midst of a mosquito abatement program. He says that country has a strong public health system and Rio is a relatively modern city.

There have been concerns over the government’s ability to carry out public health programs because of recent political instability, but Rutherford thinks they’ll follow through with efforts to reduce the Zika virus threat.

“They aren’t going to screw around with this,” he said.

Hawkinson says preventative measures can be taken around the Olympic Village, where the athletes stay. Fumigation and putting screens on windows are among them.

“Steps can be taken that can be effective,” he said.

He and others urged people traveling to Brazil to avoid mosquitoes, wear long sleeve shirts and long pants, and bring plenty of insect repellant.

“Buy a lot of bug spray and use it unsparingly,” he said.

Read More: Unsafe Environments Cause One-Fourth of World’s Deaths »

What’s in the Water?

Beyond mosquitoes flying in the air, there are also concerns of what is lurking in the water near the Olympic sites.

When it submitted its bid to host the 2016 Olympics, Brazil promised to clean up the bays and beaches near Rio.

According to an article in The Atlantic and other publications, Brazil hasn’t made the water quality progress it and others would have like to have seen.

The Atlantic reported Brazil officials say they won’t meet their goal of treating 80 percent of the raw sewage that flows into the bays near Rio. They expect to hit about 65 percent.

Tests conducted by The Associated Press last year showed Olympic waterways were rife with pathogens.

Eric Heil, an Olympic sailor, was treated at a German hospital for flesh-eating bacteria he contracted shortly after sailing in an Olympic test event near Rio last August.

Competitors in sailing events are likely to be exposed to bacteria and viruses from the water. Triathletes who must swim in the bays as part of their event are at even higher risk.

Jackie Buell, director of sports nutrition at The Ohio State University Wexner Medical Center, told Healthline bacteria could be ingested while swallowing water.

Buell noted that athletes tend to have strong immune systems, but heavy training sometimes weakens it.

There is also the danger of drinking water in Brazil.

Buell said this is a concern any time you visit a foreign country, but it could be more of an issue in Brazil this summer.

She said Olympic athletes usually have a corporate sponsor that provides them with imported water and other liquids.

“I’d be shocked if any of them drank the water there,” she said.

The Olympic Village is also an isolated community where there is usually a focus on precautions.

Buell advised anyone traveling to Brazil for the Olympics to buy bottles or cans of liquids that have been imported from developed countries.

She said extra caution should be taken. You can even get sick from ice cubes that are put into glasses of soda or alcohol.