The water quality of recreational water areas may be poor because of contamination from feces, other organic matter, or free-living microorganisms introduced by human or animal fecal contamination, sewage spills, or animal waste runoff following rainfall. Human contamination can occur because people have not thoroughly cleaned their rear end before entering the water and especially when someone has diarrhea or defecates into the water. Beach sand may be contaminated, especially from animal fecal material, primarily of dogs and birds, but also of any wild or domesticated animals. Algae, which may be toxic to humans, may also be found in this environment. Recreational water illness may be caused by microorganisms that enter the body most frequently through swallowing the water, breathing mist or aerosols, and being in contact with the contaminated water in any of the constructed or natural swimming areas.
For example, in coastal waters, Vibrio parahaemolyticus and Vibrio vulnificus can not only cause disease by humans eating raw oysters or other raw shellfish but also can cause disease if the individual has an open cut and comes in contact with the organisms in warm seawater. Whereas the first organism has typically a mild effect on the individual with a self-limiting gastrointestinal illness, the second organism can cause a severe gastrointestinal disease and, especially for immunocompromised individuals, lead to severe life-threatening illness with potential for septic shock and death. (See endnote 62.)
Contamination may also be found on surfaces surrounding the water. The most frequent illness reported is gastroenteritis and the leading cause of disease is Cryptosporidium.
Hot tubs and spas have been the sources of rashes for people of all ages because of infection with Pseudomonas aeruginosa. This type of rash can also occur in swimming pools which have not been properly maintained. Typically, disinfectant and pH levels are not correct.
Decorative water fountains may not be chlorinated or filtered and when children, especially those of diaper age, play in the water they may contaminate it with fecal matter. When another child or the same child swallows the contaminated water, they can become ill with various gastrointestinal diseases.
Since 1978, the number of outbreaks of recreational waterborne disease has increased substantially. They have been caused by Cryptosporidium, Pseudomonas, Legionella, Giardia, Shigella, E. coli, norovirus, Campylobacter, adenovirus, hepatitis A, Salmonella, Staphylococcus, Streptococcus, and disinfecting agents and their byproducts. From January 2007 through December 2008, there were 134 recreational water-associated outbreaks reported in 38 different states, with 116 of the outbreaks occurring in treated recreational water including pools and interactive fountains. This resulted in 13,480 cases with over 60% being acute gastrointestinal illness. Also there were dermatological illnesses and acute respiratory illnesses. This was a substantial increase over the 78 outbreaks reported for 2005-2006. Previously, recreational water outbreaks of Legionnaires’ disease had been reported. A total of 62 outbreaks of gastrointestinal disease were associated with parasites especially Cryptosporidium. Giardia has also been found in pool water. E. coli 0157:H7 has been found in water slides and interactive fountains in water parks. Shigella has caused outbreaks as has Pseudomonas. Norovirus was the etiological agent in five outbreaks of disease. Nine outbreaks of disease were due to chemicals or toxins. Improper levels of chlorine or bromine, improper pH, and contact time contribute to the dissemination of the disease organisms.
Although all individuals are subjected to a variety of organisms and may become sick, those who are most vulnerable are children, pregnant women, and individuals with weakened immune systems. Individuals who have had organ transplants or chemotherapy are also greatly at risk.