A 10 year survey of the epidemiology and clinical aspects of listeriosis in a provincial English city.

Between January 1983 and December 1992 29 cases of human listeriosis were recorded in Bristol, giving an incidence for the decade of 0.35 infections/10(5) population/annum. For those less than a year old the incidence was 5.2/10(5) population/annum and for adults increased from 0.029/10(5)/annum for those aged 20-49 years to 0.65/10(5)/annum for those over 80 years of age. Social classes I and II were over represented in those infected while classes IV and V were under represented when compared to the general population. Infection was seasonal with most infections occurring in October and 75.9% cases in the last two quarters of the year. Altogether, 13 (45%) cases were associated with pregnancy while 16 (55%) arose in non-pregnant persons. The incidence of pregnancy-associated infection was 1.23 per 10(4) births. In the first half of the decade, pregnancy-associated infection (62.5%) was more common than infection in non-pregnant adults or juveniles but this preponderance was reversed in the second half (23.1%). Among juvenile/adult infections not associated with pregnancy, bacteraemia became more common than CNS infection as the decade progressed. Among the pregnancy-associated infections were five infected abortions, seven neonatal infections (six systemic and one local) and one maternal infection during pregnancy in which the baby was not infected. The juvenile and adult infections in non-pregnant adults presented as primary bacteraemia in 10 (62.5%) patients and CNS infection in six (37.5%) patients. The overall mortality, excluding abortions, was 27.6% (8/29), being 14.3% (1/7) among affected neonates and 37.5% (6/16) among juveniles and non-pregnant adults. Sequelae of infection were not noted in the neonates but a third of the juveniles or adults with CNS infection were left with residual defects.