Waterborne pathogens and swimming
NEWS IN BRIEF — Posted July 23, 2007
The levels of potentially harmful waterborne microorganisms in rivers, lakes and other recreational waterways may be highest when the water is most crowded with swimmers, according to studies made available online in advance of their publication in Applied Environmental Microbiology and Water Research.
Johns Hopkins Bloomberg School of Public Health researchers tested the water at a beach on a Maryland river last summer on Wednesdays, when activity was low, and on Saturdays, when it was high. The concentration of microsporidian spores, Cryptosporidium parvum, which causes cryptosporidiosis, and Giardia lamblia, which causes giardiasis, were highest on the weekend. Water turbidity also was highest then, suggesting that swimmers stir up the pathogens resting in the sediment.
Exposure to these microorganisms can cause nausea, vomiting and diarrhea. They are particularly harmful to people with compromised immunity.
Note: This item originally appeared at http://www.ama-assn.org/amednews/2007/07/23/hlbf0723.htm.