A bulletin for the Australian Food Industry September 1996
Contents: Salmonella: more unusual incidents | Ciguatera poisoning | Phthalates in foods | Ozone treatment of mineral water | Effective sanitation programs | Thermal processing of foods | Transfer of allergens in genetic manipulation of foods | National food hygiene standards
Salmonella: more unusual incidents
In the previous issue of Food Safety and Hygiene attention was drawn to the fact that many foods can act as a vehicle for Salmonella spp infection.
It is inappropriate at this time to comment on the recent salmonella food poisoning incidents in Australia and New Zealand associated with peanut butter. However there are indications from publicly available information that the infective dose in many cases was very low.
In Germany in 1993 an outbreak of salmonellosis which affected 1,000 people, principally children, was traced to contaminated paprika and paprika-powdered potato chips. Levels of 0.04 - 0.45 organisms per gram were found in the snacks. Three different serotypes were involved. (Epidemiology and Infection 115 (3) 1995 pp.501-511).
While the classic concept is still valid that ingestion of large numbers of metabolically active salmonellae is necessary to cause illness, this incident is further evidence that low numbers of quiescent organisms are also able to cause infection at least in young people.
Studies in the United Kingdom in the 1980s suggested that in salmonellosis incidents associated with chocolate, an infective dose of approximately 50 organisms could cause illness. This was equivalent to an average value of 1.6 S. Napoli organisms per gram of chocolate bar.
Evidence in this outbreak indicated that milk chocolate conferred some protection on the salmonellae, permitting long term survival in a relatively dry product and resistance to gastric acidity.
The authors of the paper in Epidemiology and Infection referred to above, make the point that the paprika incident reflects the problem of modern mass-produced food which may rapidly reach vast numbers of consumers and which is characterised by the fact that a product with a level of contamination capable of infecting perhaps only 1 in 10,000 exposed persons may achieve considerable public health importance. They recommend that HACCP (Hazard Analysis Critical Control Point) systems must consider the whole process including production of raw materials.
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