Apr 25 2007

Seawater & pathogens

Published by at 10:42 am under surf environment,unfinished stuff

Human health risk from micro-organisms in the Australian marine environment
Nicholas J. Ashbolt
AWT Science & Environment
West Ryde, NSW 2114

In Australia, faecal pollution in seawater is inferred from the presence of certain indicator bacteria, primarily faecal coliforms and/or faecal streptococci (includes the enterococci). However, epidemiological studies of waterborne illness indicate that the common aetiological agents are more likely to be viruses and parasitic protozoa than bacteria (Moore et al. 1994; Seyfried et al. 1985; Cabelli et al. 1982). Furthermore, the recent literature illustrates the poor correlations between waterborne human viruses and faecal coliforms in marine waters (Deuter et al. 1991). This lack of a relationship relates in part to the sporadic presence of pathogens in sewage, which reflects the incidence of illness in the population. In addition, there are problems in sampling (Fleisher 1990), and many pathogens survive longer than the faecal indicator bacteria determined by culturing methods (Evison 1988), with viruses present when indicator bacteria are absent (Hughes et al. 1991). A further complication is the occurrence of nonculturable but viable indicator bacteria which are not enumerated by standard methods and result in further underestimation of pathogen presence (Byrd et al. 1991; Green et al. 1991).

See table 2 for list of pathogens/symptoms/survival time

WHO paper entitled Bathing Water Quality and Human Health (click here for the PDF)

From www.epa.gov

What harmful microorganisms can be found in polluted water and what illnesses do they cause?

Polluted runoff and untreated sewage released into the water can expose swimmers to bacteria, viruses, and protozoans. These pathogens (disease-causing organisms) can be present at or near the site where polluted discharges enter the water. Children, the elderly, and people with weakened immune systems are most likely to develop illnesses or infections after swimming in polluted water.

Swimming-related illnesses are typically minor. This means that they require little or no treatment, respond readily to treatment, and have no long-term health effects. The most common illness associated with swimming in water polluted by sewage is gastroenteritis. It occurs in a variety of forms that can have one or more of the following symptoms: nausea, vomiting, stomachache, diarrhea, headache, and fever. Other minor illnesses associated with swimming include ear, eye, nose, and throat infections. In highly polluted water, swimmers may occasionally be exposed to more serious diseases like dysentery, hepatitis, cholera, and typhoid fever. .

Agencies monitoring for beach water pollution usually analyze the water samples they collect for indicator species to assess the water for harmful levels of pathogens. Collecting and measuring the pathogens directly can be difficult and potentially hazardous. Good indicator species are microorganisms that are easy to collect and analyze for, safe to handle, representative of the pathogen of concern for characteristics like growth, and always present when pathogens are present or vice versa.

& from the same page:

People who swim in water near storm drains can become ill. A recent Southern California epidemiological study, for example, revealed that individuals who swim in areas adjacent to flowing storm drains were 50 percent more likely to develop a variety of symptoms than those who swim further away from the same drain. Swimmers who did not avoid the drains experienced an increased risk for a broad range of adverse health effects. These include fever, nausea, and gastroenteritis; flu-like symptoms — such as nasal congestion, sore throat, fever, and/or coughing– are also possible. Storm drains can even be a source of problems during drier weather because broken pipes or connections to sanitary disposal systems may contribute pathogens to the storm drains.

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