Metlife Stadium in Rutherford, N.J. is one of 16 stadiums hosting 2026 FIFA World Cup matches in the U.S., Canada, and Mexico. —Johnrob—Getty ImagesAny time people from around the world gather together, the risk of certain diseases goes up. With the World Cup underway, health experts are on alert for infectious diseases. Here are some tips from infectious-disease and public-health experts about what to worry about, what not to worry about, and how to best protect yourself.Hantavirus and Ebola have been in the headlines. How worried should I be if I’m attending a match?The risk of getting infected with either virus remains low for the general U.S. public for several reasons. First, both viruses are transmitted by direct contact with an infected person (or rodent, in the case of hantavirus). In the U.S., cases of hantavirus are generally reported in the Pacific Northwest, but some Americans were recently exposed during a cruise that originated in Argentina, where the virus is more common. Those exposed passengers were evacuated to a special biocontainment facility in Nebraska where they were monitored for any signs of disease, and many passengers have been discharged after remaining symptom-free for a period of time. Ebola is transmitted from certain animal species like bats and primates, and while the current outbreak in the Democratic Republic of Congo (DRC) and Uganda is concerning, health officials there are exit-screening people leaving those countries in hopes of keeping the virus contained. The U.S. also recently imposed additional restrictions for anyone arriving in the country from the DRC, Uganda, or South Sudan. The DRC’s World Cup team is training in Houston and changed its training schedule, according to Politico, in part due to U.S. entry restrictions for travelers from the country. The team had planned on convening in the capital city of Kinshasa before flying to the U.S., but the players, who were already out of the country for a match, flew directly to Europe instead. The U.S. Centers for Disease Control and Prevention (CDC) is working with team officials to ensure safe training procedures are in place for the players, officials told Politico. For fans from the DRC traveling to the U.S., those who already received visas will have to spend the 21 days before arriving in the U.S. outside of the DRC, Uganda, and South Sudan, according to current U.S. entry restrictions. Those without visas may not be issued one since the U.S. embassy in the DRC has temporarily suspended issuing visas. What is the biggest infectious disease risk at World Cup matches?Health experts say the more realistic worry is about respiratory diseases like the cold, flu, RSV, and COVID. These spread readily through the air—via coughs and sneezes—especially in crowded conditions. Many stadiums are outdoors, which helps cut down on transmission, but being in tight quarters next to someone who is sick could make you sick as well. “Right now, it’s cold and flu season in the southern hemisphere,” says Dr. Daniel Egan, an infectious-disease physician at Orlando Health. “World Cup matches are a unique scenario of mixing people coming from that area with people up north. Respiratory illnesses are honestly the biggest spreading-possibility illness now.”How can I protect myself from getting sick?It's advice you've heard since childhood, but doctors say the best defense against germs is washing your hands. Traditional soap and water work on a number of levels, from the physical removal and destruction of microbes on your hands to cleaning away any dirt and grime. Finding a sink is the best option, but if one isn’t convenient, then hand sanitizer is a good substitute, says Egan. But, he says, “If you compare them head to head, then soap and water beats out hand sanitizer every single time.” Beyond washing your hands, it’s also helpful to be aware of what your hands are touching. “In any big crowd, it’s a challenge to think of all the different areas that people touch,” says Egan. “Guard rails, handrails, countertops—a lot of people are touching these areas, and that’s how diseases spread.” Viruses like norovirus and stomach bugs that cause gastrointestinal distress are usually spread via contaminated surfaces.The best way to protect yourself from these germs is to also wash your hands—both before and after you use the restroom. That way, any microbes you may pick up from touching surfaces won’t be spread while you undress or use the bathroom. “People have no idea of the surfaces they touch before they go to the bathroom,” says Egan.Are health officials tracking the World Cup for diseases?Health officials are turning to a relatively new way of monitoring microbes that proved useful during COVID: through wastewater. Scientists have developed ultra-sensitive ways to pick up traces of viruses like influenza, COVID, RSV, and more. They use a technology that amplifies tiny signals of pathogenic genes to determine whether certain diseases are rising in a sampled area. Verily Health, an offshoot of Google X, began monitoring wastewater for infectious diseases during COVID in 2020, and now works with the CDC and others to provide up-to-date information on disease trends picked up in wastewater. For the World Cup, Georgetown University and MedStar Health created the Health Security Operations Center, the first non-government public-health emergency center to monitor for infectious diseases. Verily is contributing to the information the operations center is tracking to stay on top of infectious disease trends, by looking for about 30 infectious diseases in wastewater, including in cities where World Cup teams are training. (They are not currently looking for Ebola, but they can if it becomes necessary.) The wastewater monitoring “is public-health response on steroids,” says Dr. Vindell Washington, chief physician executive of Verily. When samples from local wastewater plants come in, they take about three days to fully analyze, he says, compared to the several weeks it might take for people to develop symptoms, get tested, and wait for the results. He says Verily will analyze the data and post them on a website to help people make more informed decisions about infectious-disease risk. Someone with COPD or asthma, for example, could check the dashboard for respiratory illnesses in the area of the game.Doctors can also take advantage of the information to spot trends in a patient's area. Knowing that RSV cases are rising nearby, for example, may raise their suspicion for that virus, which could help guide testing and treatment.It’s part of the effort to empower people with better, real-time information that can have a direct impact in improving their health. “This World Cup is a step forward—we have people coming from around the world, and the disease environment could change relatively quickly,” says Washington. “We need a signal today, and not six weeks from today.”