Researchers at the National Institute of Health Sciences in Japan have published a paper in the current issue of Epidemiology and Infection which provides guidance for the relative risk-assessment of  infective doses of common foodborne pathogens.

Because of copyright restrictions, we are permitted only to provide the abstract. Researchers with access to Cambridge Journals can read the full article as cited below.

Y. HARA-KUDO and K. TAKATORI (2011). Contamination level and ingestion dose of foodborne pathogens associated with infections. Epidemiology and Infection, 139, pp 1505-1510 doi:10.1017/S095026881000292X

Intake of a small dose of foodborne pathogens can cause infection. In this study, an estimation of the infectious dose of the pathogens was obtained by conducting microbiological risk assessments. The contamination levels of foodborne pathogens were analysed in 17 outbreaks of Salmonella, Escherichia coli O157, enterotoxigenic E. coli, Vibrio parahaemolyticus, and Campylobacter jejuni occurring in Japan between 2004 and 2006. The infectious dose was estimated in 14 of the 17 outbreaks utilizing existing data. In three outbreaks of Salmonella infection in which the infection rate was 89–100%, the dose of the ingested pathogens was estimated to be 259 000–14 000 000 000 c.f.u. In other outbreaks of Salmonella infection, the infection rate and dose of the ingested pathogens were 10–66·4% and 81–1560 c.f.u. or most probable number (MPN), respectively. The ingested Salmonella dose is likely to be related to the infection rate; however, storage conditions should be taken into account when making this determination. In an outbreak of E. coli O157 infection, the infection rate and ingestion dose were 100% and 2 to <9 c.f.u., respectively, while in an outbreak of enterotoxigenic E. coli infection, they were 93% and 25–1000 c.f.u., respectively. Finally, in an outbreak of C. jejuni infection, the infection rate and ingestion dose were 37·5% and 360 MPN, respectively. These results will be particularly valuable for risk assessment.