Illnesses From Contaminated Swimming Water Increasing

Latest CDC Data Show an Increase in Disease Outbreaks From Bacteria in Swimming Water

Medically Reviewed by Laura J. Martin, MD on September 22, 2011
From the WebMD Archives

Sept. 22, 2011 -- Eight people died and about 14,000 people in 38 states and Puerto Rico were sickened by bacteria and other bugs picked up during recreational swimming activities in a two-year period ending in December 2008, a new CDC report shows.

In addition, more than 4,000 people were sickened and three died due to drinking dirty water in the same January 2007-December 2008 period, according to a separate CDC study of data from 23 states and Puerto Rico.

Both reports are published in the CDC's Morbidity and Mortality Weekly Report (MMWR) for Sept. 23.

CDC researchers say there were 134 outbreaks of recreational water illness, the highest number ever reported in a two-year period and a 72% increase since 2005-2006.

The outbreaks were linked to swimming pools, spas, lakes, rivers, and ocean water; 45% were caused by cryptosporidium, characterized by the CDC as an "extremely chlorine-tolerant parasite."

Of the 134 outbreaks, 60.4% caused gastrointestinal illness, 17.9% skin problems, and 12.7% acute respiratory disease.

Almost two-thirds of the outbreaks started during the traditional summer swimming season, which runs from Memorial Day through Labor Day.

The researchers call for improvements in swimming pool disinfection and operation, tougher pool regulations, and enforcement of rules and better swimmer hygiene.

Tips to Prevent Illness

The CDC offers these tips that may cut down on illnesses related to recreational swimming:

  • Don't swim when you have diarrhea because this can spread germs in the water and sicken other people.
  • Don't swallow pool water and avoid getting water in your mouth.
  • Practice good hygiene. Before swimming, shower with soap and wash your hands after using the toilet or changing diapers to prevent germs from winding up in the water.

In addition, the CDC report documents more than 4,000 illnesses and injuries caused by pool chemicals each year in the 2007-2008 period. These were linked to both private and public pools. The illnesses often can be prevented by proper chemical-handling practices.

The CDC reports that in the two-year period, there were eight fatal cases of primary amebic meningoencephalitis -- a rare but deadly brain infection caused by the freshwater amoeba Naegleria fowleri.

The fatal cases all were linked to exposure to untreated fresh water in lakes and ponds. The only sure way to prevent such infections is to stay away from activities in warm fresh water.

Contaminated Drinking Water

In the second report on illnesses due to drinking water, CDC researchers counted 36 outbreaks in 23 states and Puerto Rico that led to 4,128 illnesses and three deaths.

More than half of the episodes were associated with untreated or inadequately treated ground water, an indication, according to the researchers, that ground water contamination remains a significant public health problem. Additional efforts are needed to monitor and protect sources of ground water.

Outbreaks associated with drinking water were caused by bacteria, viruses, parasites, and chemicals. Legionella alone accounted for a third of the drinking water outbreaks.

Legionella, which leads to 8,000-18,000 hospitalizations annually, can cause severe respiratory illness.