Listeriosis surveillance: 1991.

A total of 130 cases of listeriosis was reported in England, Wales and Northern Ireland in 1991. This represents a slight increase on the 1990 total of 118 reports but a marked decline compared with the peak incidence of reporting of 291 in 1988, which was part of an upsurge of cases between 1987 and mid 1989. Two epidemiological features of note in 1991 were the reappearance of a late summer-autumn peak in cases (commonly seen prior to 1987) and an increase in the number of reports among younger patients and children. The decline in listeriosis observed during the second half of 1989, which followed government health warnings about the consumption of pâté, and the continued low level of reporting since 1989 may be due to the disappearance of a common food source. However, in the light of the recent outbreak of listeriosis in France it is important that diagnostic vigilance and warnings about high risk foods are maintained.