On May 17, 2018, the CDC published a report that found that, between 2000 and 2014, 493 waterborne disease outbreaks associated with treated recreational water caused at least 27,219 cases and eight deaths. A third of treated recreational waterborne disease outbreaks between 2000 and 2014 occurred in hotel pools or hot tubs.
Cryptosporidium (also known as Crypto), Pseudomonas, and Legionella caused most of the outbreaks in swimming venues in the United States during this time period. Crypto is a parasite tough enough to survive even in properly maintained pools, which causes predominantly gastrointestinal illness. Pseudomonas and Legionella are bacteria that can survive disinfectants in slimy areas of hot tubs, pools, and water playgrounds. Pseudomonas causes folliculitis, also known as hot tub rash, and otitis externa, commonly known as swimmers’ ear. Legionella causes Legionnaires’ disease, a severe pneumonia, and Pontiac fever, a milder illness with flu-like symptoms. Some people are more likely to get sick from Legionella, including people 50 years or older, current or former smokers, people with chronic lung disease, and people with a weakened immune system.
The report described mixed progress in preventing outbreaks caused by germs spread through treated recreational water. The number of respiratory disease outbreaks caused by Legionella increased over time and skin infection outbreaks caused by Pseudomonas decreased over time. Diarrheal disease outbreaks caused by Cryptosporidium leveled off between 2008 and 2014. More than half of outbreaks started in the summer, the peak season for swimming.
Crypto caused 58 percent of outbreaks where a germ was identified linked to pools, hot tubs, and water playgrounds and 89 percent of the illnesses. Crypto spreads in pools when someone sick with the parasite has diarrhea in the water and other swimmers swallow that contaminated water.
“Swallowing just a mouthful of water with Crypto in it can make otherwise healthy kids and adults sick for weeks with watery diarrhea, stomach cramps, nausea, and vomiting,” said Michele Hlavsa, R.N., M.P.H., chief of the CDC’s Healthy Swimming Program. “Chlorine cannot kill Crypto quickly. We need to keep it out of the water in the first place. Don’t go into the water, and don’t let your kids go into the water, if sick with diarrhea.”
The bacteria Legionella and Pseudomonas are the next most leading causes of these outbreaks, with 16 percent of outbreaks caused by Legionella and 13 percent caused by Pseudomonas. If a pool, hot tub, or water playground is not cleaned properly, bacteria can grow and form a slime called biofilm on wet surfaces. Legionella and Pseudomonas can live in this biofilm. It is harder for disinfectants to kill these bacteria when they are protected by biofilm. Pool operators need to maintain proper cleaning practices and disinfectant levels to prevent bacteria from growing and causing illnesses in swimmers. The CDC provides specific recommendations for operating public pools, hot tubs, and water playgrounds in the Model Aquatic Health Code.
See the CDC Announcement
See the CDC Report
See also Medical Risk Law Report: Gut-Wrenching Pain: Liability Risks Related to Gastrointestinal Disorders