Most of our patients have been or will be exposed to water in a recreational setting this summer. As health care providers, we might not routinely consider illnesses associated with recreational water exposure or discuss preventive strategies; however, the Centers for Disease Control and Prevention has been actively promoting awareness about recreational water illnesses for years. May 18-24, 2015, was the 11th annual observance of Healthy and Safe Swimming Week, formerly known as Recreational Illness and Injury Prevention Week. The focus for 2015 was promoting the role of swimmers, residential pool owners, public health officials, and beach staff in the prevention of drownings, chemical injuries, and outbreaks of illness. One goal was for the swimmer to take a more active role in protecting themselves and preventing the spread of infections to others. For our colleagues, that means educating both parents and children.
To begin our discussion, let’s define recreational water illnesses (RWI). RWIs are caused by a variety of infectious pathogens transmitted by ingestion, inhalation of aerosols or mists, or having contact with contaminated water from both treated (swimming pools, hot tubs, water parks, and fountains) and untreated (lakes, rivers, and oceans) sources of water in recreational venues. RWIs also can be caused by chemicals that have evaporated from water leading to poor indoor air quality. However, I am focusing on the infectious etiologies.
A broad spectrum of infections are associated with RWIs, including infections of the gastrointestinal tract, ear, skin, eye, central nervous system, and wounds. Diarrhea is the most common infection. Implicated pathogens include Giardia, Shigella, norovirus, and Escherichia coli O157:H7, but it is Cryptosporidium that has emerged as the pathogen implicated most often in swimming pool–related outbreaks. Recently published data from the CDC revealed that in 2011-2012, there were 90 recreational-associated outbreaks reported from 32 states and Puerto Rico resulting in 1,788 infections, with 69 outbreaks occurring in treated water venues. Of these, 36 (51%) were caused by Cryptosporidium. Among 21 outbreaks occurring in untreated recreational water, E. coli was responsible for 7 (33%) (MMWR Morb. Mortal. Wkly Rep. 2015;64:668-72)
It’s no surprise diarrhea is the most common illness. Infection can easily occur after swallowing contaminated water. Many erroneously think chlorine kills all pathogens. Cryptosporidium is chlorine tolerant and can persist in treated water with the current recommended levels of chlorine for more than 10 days (J. Water Health 2008;6:513-20). For chlorine-sensitive pathogens, maintenance of the disinfection process must remain intact. What role do swimmers play? Most people have about 0.4 g of feces on their bottoms that can contaminate water when rinsed off. How many people enter a pool with a diarrheal illness? How many may go swimming after having recently recovered from a diarrheal illness and may have asymptomatic shedding? We all have cringed when we see a diapered child in the water. All of these are potential ways for the swimmer to contaminate an adequately treated pool. Additionally, while Cryptosporidium infections are usually self-limited, some individuals, including the immunocompromised host and especially those with advanced HIV and those who are solid organ transplant recipients, may have a protracted course of profuse diarrhea if infected.
While diarrhea maybe the most common RWI, it is not the only one. Acute otitis externa (AOE), more commonly known as “swimmer’s ear,” is one of the most frequent reasons for summer health care encounters. It has been estimated that in the United States in 2007, 2.4 million health care visits resulted in the diagnosis of AOE (MMWR Morb. Mortal. Wkly. Rep. 2011;60:605-9). Visits were highest among children aged 5-9 years; however, adults accounted for 53% of the encounters. Inflammation and infection of the external auditory canal is usually caused by bacteria. Pseudomonas aeruginosa or Staphylococcus aureus are the two most common etiologies. Water is easily introduced into the external auditory canal with recreational water activities, leading to maceration and subsequent infection of the canal. Simply reminding parents to thoroughly dry their child’s ears after water exposure can help prevent AOE.
P. aeruginosa also is the agent causing the self-limiting conditions hot tub folliculitis and hot-foot syndrome. Hot tub folliculitis is characterized by the development of tender, pruritic papules and papulopustules on the hips, buttocks, and axillae, usually developing 8-48 hours after exposure to water that has been contaminated because of inadequate chlorination. Hot-foot syndrome is characterized by painful planter nodules (N. Engl. J. Med. 2001;345:335).
Serious diseases are encountered infrequently, but there are some that require more urgent interventions. Primary amebic meningoencephalitis (PAM) is an extremely rare, progressive, and almost always fatal infection of the brain caused by Naegleria fowleri. The pathogen is found in warm freshwater including lakes, rivers, streams, and hot springs. It enters the body through the nose and travels via the olfactory nerve to the brain. Infection usually occurs when individuals swim or dive in warm freshwater. Most cases have been reported in children from Southern states. In 2010, the first case in a northern state was reported from Minnesota, and three additional cases have since been reported in Kansas and Indiana (J. Ped. Infect. Dis. 2014 [doi: 10.1093/jpids/piu103]). Cases also have been reported in two individuals who were regular users of neti pots for sinus irrigation because the irrigating solution was prepared with contaminated tap water (Clin. Infect. Dis. 2012;55:e79-85). Clinical presentation is similar to bacterial meningitis. Helpful diagnostic clues may come from obtaining a history of swimming in freshwater within the 2 weeks prior to presentation, especially during the summer, or the use of nasal or sinus irrigation with untreated tap water. Consultation with an infectious disease specialist is recommended.