During October 1992 an increase in the number of isolates of Salmonella mikawasima, a rare serotype, was noted including a cluster of nine cases in the South West Thames region. A case control study was conducted and univariate analysis showed a statistical association between illness and eating at takeaway A for cases compared with household controls (P = O003) and with neighbourhood controls (P = 0.0245). Cases were also more likely to have eaten kebabs than were controls or average takeaway A customers, implicating doner kebabs as the most likely vehicle of infection. Plasmid profile analysis of the nine cases' isolates showed them to be indistinguishable and to be characterized by a single plasmid of approximately 60 MDa.
The original source of the Salmonella mikawasima contamination was not determined, but food preparation practices for kebabs at takeaway A were insufficient to protect against illness if contaminated. This outbreak was only recognized because of the unusual serotype, but could be an indication of a more widespread problem with doner kebabs.