Swimming-associated gastroenteritis and water quality

Area of Science:

• Environmental microbiology
• Epidemiology
• Public health

Background:

• Recreational water use is linked to gastrointestinal illness.
• Microbial indicators are used to assess water quality.
• Previous studies suggested a link between water quality and illness.

Purpose of the Study:

• To establish a direct relationship between bathing water quality and swimming-associated gastrointestinal illness.
• To identify the most effective microbial indicator for assessing water quality related to illness.
• To determine the risk of illness from swimming in polluted waters.

Main Methods:

• A multi-year, multi-location prospective epidemiologic-microbiologic study.
• Collected data from New York City, Lake Pontchartrain, and Boston.
• Assessed various microbial indicators, including enterococci and Escherichia coli.
• Correlated microbial data with reported gastrointestinal symptoms in swimmers and non-swimmers.

Main Results:

• A direct, linear relationship was found between bathing water quality and gastrointestinal illness.
• Enterococci demonstrated the strongest correlation with gastrointestinal symptoms.
• Low enterococci and E. coli densities (10/100 ml) were associated with significant illness rates.
• Swimming in marginally polluted water significantly increased gastroenteritis risk.

Conclusions:

• Bathing water quality is a critical factor in preventing swimming-associated gastrointestinal illness.
• Enterococci serve as a reliable indicator for assessing the health risks of recreational waters.
• Even slightly polluted marine waters pose a significant risk for gastroenteritis transmission through swimming.