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Increases in Recreational Water Illness at Hotels Needs More Attention

A great focal point of a family vacation is often the hotel pool. It can be loud, the sun loungers scarce and dry towels hard to find, but the children love it and you can almost ignore the inevitable screams of delight to allow yourself a few minutes to relax.

Hundreds of thousands of us use hotel swimming pools every year. We do so knowing that they are owned and operated by legitimate businesses that have your best interests at heart. The pool water is clear, you can smell the chlorine and that usually gives us peace of mind. But lurking in that clear, chlorinated water can be cryptosporidium, legionella and pseudomonas. All organisms that can send you or members of your family running to the bathroom, or worse, the hospital.

From 2000 to 2014 there were 493 cases of recreational water illnesses (RWI) reported, resulting in 27,219 individual illnesses and eight deaths. Of the 493 cases of RWI, 157 (32%) were reported to have occurred at hotels. The leading culprit was cryptosporidium, which causes gastrointestinal illness. This was followed by legionella, which causes severe pneumonia and Pontiac fever, a milder illness with flu-like symptoms. Finally pseudomonas, which causes swimmers ear and hot tub rash.

Of the 493 reported cases at hotels, over half of the outbreaks occurred in the months of June, July and August, coinciding with the summer vacation season. However, with the number of indoor aquatic facilities at hotels increasing, it is expected that these outbreaks will transition from being predominantly in the summertime, to all year round.

Water Illnesses Chart

FIGURE 1. Number of outbreaks associated with treated recreational water (N = 493), by etiology and month — United States, 2000–2014*

Hotels are not the only venues faced with this problem. Hot tubs and spas, interactive water features, community pools, school pools, private pools and any aquatic facility is a breeding ground for these organisms.

Cryptosporidium events occur due to diarrhea being introduced to the water and it subsequently being ingested. For most facilities the `go to’ treatment is chlorine, but cryptosporidium is extremely chlorine-resistant. The Centers for Disease Control and Prevention (CDC) recommends a concentration of at least 1 ppm of free chlorine to inactivate most pathogens within a few minutes, but cryptosporidium can survive for more than seven days. Cryptosporidium’s tolerance to chlorine allows it to survive in the water, produce outbreaks that may spread to multiple aquatic venues and cause thousands to become sick.

In contrast, legionella and pseudomonas do not have the same resistance as cryptosporidium and are effectively controlled using chlorine. However, these pathogens must have the proper concentrations of chlorine present in the water for inactivation to occur. In 2013 a study found that out of 13,864 inspections, 20% of the venues were not maintaining proper levels of disinfectants.

The CDC recommends that when a diarrhea incident occurs, the water be hyperchlorinated to achieve a 3-log inactivation of cryptosporidium. Ultraviolet disinfection and ozone equipment are both effective in eliminating cryptosporidium, legionella and pseudomonas. Ultraviolet technology is listed within the Model Aquatic Health Code (MAHC) as an approved secondary disinfectant for aquatic venues and is strongly recommended when there is an increased risk of contamination (e.g. aquatic venues intended for children aged <5 years old).

Unlike chlorine, ultraviolet technology inactivates these organisms immediately and is therefore a very effective solution. However, it is important that ultraviolet systems are correctly designed and specified to ensure the water passing through them receives maximum exposure to the ultraviolet light.

Improving aquatic design, construction, operation and management of public venues is key to preventing RWI outbreaks. The adoption of MAHC by US states will help to fuel these improvements. The general public also has an important role to play in ensuring aquatic venues remain safe. Should we or our children suffer from the symptoms of diarrhea, we should not swim and must try to avoid public aquatic facilities until we are fully recovered.

By: John Psaroudis

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CDC. Morbidity and Mortality Weekly Report (MMWR)

CDC. Surveillance reports for recreational water–associated disease & outbreaks. Atlanta, GA: US Department of Health and Human Services, CDC; 2017.