Incidence of listeriosis in Connecticut

In Connecticut, 92 cases of human listeriosis were reported to the Department of Health Services from 1984 to 1988. The annual incidence per million population ranged from 7.3 in 1984 to 4.2 in 1988. The average annual incidence was 5.6 per million population. Case rates were highest in those aged 70 years and older (15.8 per million). Cases included 12 pregnant women and 11 newborns. Bacterial meningitis was the primary diagnosis in 23 cases. Of the 49 isolates of Listeria monocytogenes that were serotyped, 21 (43%) were type 4, 24 (49%) were type 1, and 4 (8%) were nontypable.