ABSTRACT
Human illnesses can be acquired from contaminated seafood through two principal routes:
As we dump more and more untreated or inadequately treated domestic sewage into rivers, estuaries, and coastal waters, the populations in those waters of microorganisms of human origin - bacteria and viruses in particular - will be increased. Dilution occurs as a result of river outflow, tidal flushing, and inshore currents, but may not take place fast enough to remove the risk of infection soon enough. Many bacteria that cause human disease neither reproduce nor survive very long in more saline ocean waters. However, they may not be killed instantaneously and so can constitute a threat to human health. Of particular concern are the microorganisms that cause cholera, typhoid, dysentery, skin infections, hepatitis, botulism, and eye and ear infections. Disease-causing bacteria of human origin, present in domestic sewage, may persist for days, weeks, or months in the intestines of fish, on the body surfaces or gills of fish and shellfish, and within the digestive tracts of shellfish, or on their gills, as well as in bottom sediments. Swimmers, skin divers, and fishermen obviously expose themselves to infection by venturing too close to ocean outfalls, sludge dumpsites, or badly degraded estuarine waters. Frequently, though, pollutants may be carried for miles by currents, so that it is difficult to determine which waters are safe and which are not, except by more or less continuous monitoring.
