The number of Americans who got sick from swimming or bathing in tainted pools, spas and other facilities jumped 21 percent to a record high during 2001 and 2002, the government said on Thursday.

Poor pool and spa maintenance, watershed contamination and the tendency of some people to swim while sick were among the factors that led to the rise in illnesses such as diarrhea and skin infections, the U.S. Centers for Disease Control and Prevention said.

Diarrhea can cause severe dehydration and is especially dangerous to pregnant women, young children and those with weak immune systems.

“When we look at these outbreaks we see a wide spectrum - from those who don’t feel particularly ill at all to those who are hospitalized,” said Michael Beach, a CDC epidemiologist.

A total of 2,536 swimmers and recreational bathers in 23 states contracted recreational-linked waterborne diseases between January 2001 and December 2002. Sixty-one people were hospitalized and eight died.

The 65 outbreaks during the period was the highest number recorded since the government began tracking the problem in 1978.

In comparison, 2,093 people contracted similar illnesses during 59 recreational water-related outbreaks in 1999-2000.

About half of the more recent diarrhea outbreaks among bathers were caused by Cryptosporidium, a microscopic chlorine-resistant parasite. Pools frequently become contaminated through fecal matter from sick adults and kids.

Beach said people should refrain from swimming until two weeks after the end of a bout of diarrhea.

He added that outbreaks could be limited by improved public awareness of diarrhea and by changing swimming pool policies to require bathroom breaks for children and separate water filtration systems for “kiddie” pools.

Swimming is the second most popular exercise in the United States. Americans make between 360 million to 400 million visits to swimming pools each year, especially during the summer months.

A separate CDC study released on Thursday showed that fewer Americans got sick from drinking water in 2001-2002 than did so in the previous two-year period.

The CDC said outbreaks of illnesses linked to drinking water had decreased by 20.5 percent.

SOURCE: Morbidity and Mortality Weekly Report, October 22, 2004.