[Epidemiological studies on Salmonella in a particular area ('Walcheren Project'). IV. The incidence of Salmonella in the sewage system, in faeces of man and pets as well as in shops, kitchens and lavatories in the village of Aagtekerke (author's transl)].

As part of the epidemiological investigations on Salmonella on the island of Walcheren, the contamination of sewage water in the village of Aagtekerke was studied over a prolonged period. These studies showed that this sewage water was frequently contaminated by large numbers of Salmonella. In the present study, efforts were made to find an answer to the question of the origins of this contamination. For this purpose, the incidence of Salmonella in the sewage system, in faeces of man and pets as well as in shops, kitchens and lavatories in the village of Aagtekerke was studied for a period of three weeks in June 1977. In addition to the findings in the sewage system (including the inlet water and effluents of the sewage works) which were positive for Salmonella, this organism was only isolated from a few faecal samples of human and animal origin. Serotyping showed that the strains isolated from human faeces were similar to those found to be present in the sewage system. This fact, in conjunction with the results of the bacterial counts. suggests that the sewage system was only contaminated by the small number of carriers. The reduction of contamination observed in the sewage system during the period of investigation could be evidence of the fact that Salmonella organisms cannot survive by themselves in an environment of this type, at least not at the temperatures recorded on collecting samples from the sewage water. Growth of organisms under more favourable conditions cannot be ruled out. An inquiry on dietary habits and kitchen hygiene of the local population showed that contamination within households. Origination with the food, is a real possibility.