Public Health Significance of Human Pathogens in the Ocean

Microorganisms pathogenic for man are continuously entering coastal waters of nations throughout the world. It has been accepted that pathogens do not survive in the marine environment, and, therefore, do not pose a threat to human health. This concept was based on the empirical observations that pathogenic microorganisms, and indicator organisms like Escherichia coli, "die-off" in seawater, i.e., cannot be grown on culture media. Data gathered in our laboratory, however, show that human pathogens in seawater become "nonculturable", but these non-culturable cells remain viable. In some cases, they are fully capable of producing pathological changes when introduced into test animals. Such results have been obtained with Vibrio cholerae, enterotoxigenic E. coli, Salmonella enteritidis and Shigella spp. Conclusions drawn from results of our work are that culture techniques alone will not suffice to ensure the safety of coastal waters, and, especially, shellfish contained in those waters.