Milk-borne salmonellosis in Scotland

Abstract

In the 10-year period between 1970 and 1979, there were 29 outbreaks of salmonella food-poisoning recorded in Scotland affecting at least 2428 persons who had consumed raw milk. Eleven of the outbreaks were restricted to farm-workers and their families resident on or near dairy farms where the bulk of the milk produced was pasteurised before sale to the public. The other 18 episodes were more widespread in the general community and affected an estimated minimum of 2290 persons who had consumed ‘premium’ or ‘standard’ grade raw milk from producer-retailer dairy farms. Twenty-one of the 29 outbreaks (72 per cent) occurred between October and March with bimodal peaks in spring and autumn. Four deaths were reported where salmonellosis was a primary or contributory cause. An attack rate of 47·6 per 100,000 of the population in Scotland and a mean of 83·7 persons per outbreak was in marked contrast to the experience in England and Wales where 69 episodes were recorded over the same period with an attack rate of 1·9 per 100,000 of the population and a mean of 13·6 per outbreak. The differences in the dairy industry in Scotland relating to the size of herds, milking methods, and the sale of raw milk, are described in comparison to the situation elsewhere in the United Kingdom. The continuing sale of unpasteurised milk is unacceptable on health grounds, and outbreaks of salmonellosis and other milk-borne infections will continue to occur until all milk sold for human consumption is heat-treated.