TracingSalmonella typhimuriuminfections

Abstract

Since the low point of 1977 the incidence of infection attributed toSalmonella typhimuriumin England and Wales has shown a steady increase with a total of 4956 cases reported in 1982 (OPCS, 1985). Although the number of general outbreaks and family outbreaks increased by 24 % and 54 % respectively between 1981 and 1982, the greatest increase (55%) was in the number of sporadic cases reported (PHLS, 1984). The cause of the recent increase in human infection is not known but may be associated with bovine infection and an explanation for the rise in sporadic cases could be that they comprise unrecognized outbreaks due to common food products distributed over wide geographical areas for long periods of time because of deep freezing (Galbraith, 1985). This hypothesis has prompted the Communicable Disease Surveillance Centre to mount a case-control study comparing sporadic cases ofS. typhimuriuminfection with an unaffected control group in several parts of the country to find the vehicles of infection. Such an approach requires precise strain identification and detailed epidemiological information.