According to the CDC’s May 18 Morbidity and Mortality Weekly Report (MMWR), there were 493 outbreaks associated with treated recreational water in the United States between the years 2000 and 2014. Those outbreaks resulted in at least 27,219 cases of illness and eight deaths. Nearly one-third (32 percent) of the disease outbreaks were associated with hotel pools, hot tubs, and spas. Most of the outbreaks occurred during summer months, when people are more likely to hit the water. The CDC defines these outbreaks as occurrences of similar illnesses in two or more people, linked by location and time of exposure. Among the 363 outbreaks with a confirmed infectious source:
Two-hundred twelve (58 percent) were traced to Cryptosporidium, also known as Crypto, a parasite that causes gastrointestinal illness.Fifty-seven (16 percent) were traced to Legionella, which can cause Legionnaires’ disease. At least six of the eight reported deaths were linked to Legionella.Forty-seven (13 percent) were traced to Pseudomonas, which causes folliculitis (“hot tub rash") and otitis externa (“swimmers’ ear”).
How Do You Protect Yourself, Others?
“We see these outbreaks every year, and they’re a reminder that the public needs to take extra steps to be more proactive about protecting their own health,” says lead author Michele Hlavsa, chief of the CDC’s Healthy Swimming Program. To avoid spreading germs to other swimmers, do not swim or let children swim when sick with diarrhea, Hlavsa says. The CDC advises waiting until two weeks after the diarrhea has stopped before swimming. “When we have diarrhea, accidents can occur and illness can spread,” says William Schaffner, MD, professor of preventive medicine and infectious diseases at Vanderbilt University in Nashville, Tennessee. “That’s also why you don’t want pets in these facilities, because they can have accidents as well.” To stop a parasite or harmful bacteria from entering the body, swimmers should avoid swallowing pool water — a common occurrence among children. “If you have kids in the water, they are going to swallow some of it, and that’s why these outbreaks are more common among children,” says Dr. Schaffner.
Check the Water Before You Get In
Recreational waters are typically treated with disinfectants such as chlorine and bromine, but these chemicals are not foolproof in controlling all pathogens. For example, Hlavsa points out that Crypto “can survive for long periods of time at chlorine levels that kill off most germs or inactivate them within minutes.” Another concern is that the water may not have been properly treated. According to the CDC, about 20 percent of 13,864 routine inspections of public hot tubs or spas conducted in 2013 found improper disinfectant concentrations. “I think we underestimate what it takes to run a pool, which is basically a big chemical reactor,” says Hlavsa. If possible, the CDC recommends checking the facility’s inspection scores. “This can mean going online to your local or state health department or checking a posting at the side of a pool,” Hlavsa says. Getting these inspection scores isn’t always easy, Schaffner admits. “Unlike restaurant inspection scores, which are often posted, these inspection scores are often filed away in the manager’s office,” he says. Another option is to check the water yourself. “Doing your own inspection is as simple as taking a test strip and checking the chlorine level and the pH to make sure they are where they need to be,” Hlavsa says. Test strips, which usually cost about $10 for a package of 50, are available at hardware stores and retailers that sell pool supplies. “We have hundreds of thousands of recreational water facilities in the country. Fortunately, the vast majority of them are not sources of illness,” says Schaffner. “I was a little surprised, however, at how frequent these outbreaks have become.” This week (May 21–27) is Healthy and Safe Swimming Week. The CDC provides more information on how to minimize the risk of water-related illness and injury on its website.
