More swimmers means more pathogens in the water

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. Researchers at the Johns Hopkins Bloomberg School of Public Health completed two studies at the Hammerman beach area along Maryland’s Gunpowder River that linked the number of swimmers using the water with the levels of microsporidian spores and the parasites Cryptosporidium parvum and Giardia lamblia. The studies were made available online in advance of publication in the scientific journals Applied and Environmental Microbiology and Water Research.