Illnesses from swimming pools are rising

The US Centers for Disease Control and Prevention (CDC) reported a rise in recreational water illnesses in 2007, and expects more in coming years.

These illnesses spread by breathing in, swallowing or touching germs in the water of swimming pools, lakes, rivers or the sea. To highlight healthy swimming habits, the CDC declared 19–25 May 2008 National Recreational Water Illness Prevention Week.

The main cause is Cryptosporidium ("Crypto"), a parasite resistant to chlorine, found mostly in treated pools and water parks. "Recreational water illnesses have been an important public health issue in the past, but they will be a big problem in the future," said Michele Hlavsa, a CDC epidemiologist. Between 2004 and 2007, Crypto cases tripled, and cases linked with swimming pools more than doubled. As Crypto resists chlorine, even well-kept pools can spread it.

Hlavsa added: "People should adopt healthy swimming habits: don't swim when you have diarrhoea, don't swallow the water, shower before swimming, wash your hands after using the toilet or changing nappies, and wash children well (especially their bottoms) with soap and water before swimming." Pool owners are urged to add extra disinfection to chlorination and filtering.

Symptoms usually start 2 to 10 days (7 on average) after infection: watery diarrhoea lasting one to three weeks, with stomach cramps and pain, dehydration, nausea, vomiting, fever and weight loss. Infection comes from swallowing contaminated water or putting something in the mouth that has touched the stool of an infected person or animal; it isn't spread through blood. Some infected people have no symptoms, and most people with a healthy immune system recover without treatment, but in people with a weak immune system it can become life-threatening.