Survey of human pathogenic bacteria and viruses in cockle beds at Otakou, Otago Harbour, New Zealand

Abstract

The Otakou area on the Otago Peninsula, New Zealand has extensive cockle beds which may be exposed to faecal contamination from several sources. Shellfish and sediments from four sites at Otakou were sampled monthly from March to August 1988 and tested for faecal coliforms, Salmonella, Shigella, Aeromonas hydrophila, Vibrio para‐haemolyticus, and enteroviruses. No pathogenic bacteria were isolated from the shellfish or the sediment samples. Poliovirus Type 1 was isolated from the shellfish on three occasions at three separate sites. Faecal coliform concentrations in the cockles were below 230 MPN/100 g on all but one occasion including the times when viruses were isolated. It was concluded that the Otakou area is subjected to sporadic faecal contamination and that the presence of faecal coliform bacteria did not provide an adequate indication of the presence of viruses.

Key words:

• cockles
• faecal coliform
• human viruses
• Chione stutchburyi
• Otago Harbour
• shellfish
• bacterial pathogens