Human listeriosis in Britain, 1967-85, a summary of 722 cases. 2. Listeriosis in non-pregnant individuals, a changing pattern of infection and seasonal incidence.

Clinical information was collected on 722 cases of Listeria monocytogenes infections in humans occurring in Britain between 1967 and 1985. This series comprised 34% (248 cases) associated with pregnancy and 66% (474 cases) in non-pregnant adults and juveniles. The cases not associated with pregnancy comprised: 76% in patients with severe underlying illness (of which 34% had central nervous system infections, and 42% bacteraemia without involvement of the central nervous system); 21% in previously healthy individuals (of whom 18% had meningitis); and 3% in patients without bacteraemia or involvement of the central nervous system. Cases occurred most often in male patients over 40 years of age. The overall mortality was 44%. Overall, the pattern of infection has altered to a disease of higher incidence, affecting most often susceptible non-pregnant individuals and the unborn. An annual increase in incidence of listeriosis occurred in the autumn in all categories of patients.