Virus Alert for Marine Sediments and for Shellfish at Foreness Point

Joseph M Gaugas PhD

Due to advances in virology research the WHO began its management programme in 1975. There is growing international concern amongst public health authorities over finding pathogenic virus contamination in both bathing water and seafood.

Enteroviruses commonly found in sewage effluent are adsorbed to marine sediments. Virus survives for long periods in the sediment but not in the overlying water (Wellings et at. 1976: Smith et al. 1978). Viruses were found in an area in the Atlantic Ocean 17 -months after cessation of sewage sludge dumping ( Goyal et al. 1984). Solids derived from sewage, rather than water phase supernatant, contain measurable amounts of viruses. The degree of adsorption is determined by pH, salinity, and type of organic matter that constitutes the sediment (LaBelle et al. 1979) In France, E.Schvoerer et al. (2000) found that five out of26 bathing areas tested positive for human pathogenic enteroviruses. Moreover, eight out of every 13 sewage samples tested were positive.

A survey of marine sediments (Spain) in a region of sewage discharge found enterovirus in just over half the number of samples tested. They were dispersed as far as 5Km from the shoreline and at a depth of 82m (Bosch et al.1988). Enterovirus was also found in the sediment of MorIa ix estuary France (Schwartzbrod et al. 1991).

Seafood ranks third on the list of products which cause foodborne diseases in the USA (Lipp et at. 1997). The UK might be expected to have a comparable incidence. Acute viroenteritis occurs more frequently in human coastal populations and its incidence is associated with storm sewage discharge (Miossec et at. 2000).

Altogether there are about half-a-dozen identified types of virus infective via the faecal-oral route that cause debilitating illnesses ( e.g. Hepatitis A, Norwalk-like virus, Enterovirus, Rotavirus and Astrovirus), even death in the most susceptible (children and the elderly),

Another three-year study by F.Le Guyader et al. (2000), also in France, showed that in coastal areas routinely impacted by human sewage discharge, around half the number of shellfish collected (oysters, mussels) were infected with such viruses.

Mussels accumulate virus and so become highly contaminated. Enterovirus has also been found in crabs.

Highest levels of shellfish contamination occurred in winter months. Crude storm sewage discharge carrying viruses will be sustained at Foreness Point even after the proposed extension to the sewage works goes ahead. So there is sustainable impact of crude sewage on the shellfish habitat.

All year round, periwinkles and mussels on the Long Nose Spit at Foreness Point are collected and taken away by the sack full, destined for eateries. In addition, picnickers are seen to collect, cook and consume shellfish on the beach. This is the foreshore Spit onto which the CSO discharges non-disinfected storm sewage!

Recently, the FEA found that foul sludge/sediment deposit occurs in patches up to 14 inches deep around the north side of the Foreness CSO pipeline. This is the organic matter on which shellfish can feed. Thus the health danger at Thanet beaches is likely to occur at anytime due to transfer along the coast of storm sewage discharges at Foreness Point containing viable pathogenic viruses.

The sludge/sediment along the side of the CSO pipeline should be tested for the presence of faecal indicator microbes. Presence of the spore bearing faecal bacterium Clostridium perfringens would be a potential indictor for sewage solids in marine sediments (Skanavis et al. 2001).

In conclusion, the EC Bathing Water Directive 1976 is outdated; and a scientific survey into the chronicity of the virus problem at the Margate sewage dispersal area and its potential risk to bathers, biodiversity, the carrier-state of both marine sediments and shellfish must now be scientifically investigated for governmental guidance.

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