Pathogenic Organisms

Detecting Pathogens and Assessing Risks

With human health at stake, the timing, frequency, speed and adequacy of water sampling and the interpretation of results are all critical to deciding whether to close a beach or issue a “boil water” advisory for drinking water. Detecting all pathogens is not possible for a number of reasons including costs, lack of appropriate tests, and sensitivity of certain tests. Therefore, water quality managers use the indicators E. coli to assess the likelihood that human pathogens may be present. Recent research indicates that at least some of the apparent high numbers of E. coli bacteria found in surface and recreational waters may not be of human origin, but rather from birds and other animals.²⁹ While this preliminary research may, in some cases, rule out human origins of E. coli, they do not report the presence of other pathogens such as Giardia, Campylobacter, or Cryptosporidium that are from animal wastes and can lead to waterborne disease outbreaks. Therefore, public health departments need tests aimed at other important pathogens to provide good information about beach safety. Authorities need to develop and use rapid, sensitive detection methods to analyze pathogens, which would enable communities to avoid unnecessary health risks by issuing earlier advisories for drinking water and swimming.