Human listeriosis in France in 1987.

The surveillance of human listeriosis is based in France on laboratories' reports. From 1983 to 1986 the trend showed a steady increase of the number of cases reported. The highest annual incidence rate was observed in 1986 with 14.7 cases/million population. In 1987 less cases have been reported; about half of the human strains were typed by the National Reference Centre of Listeriosis showing that 62% were 4b, 22% were 1/2a and 13% were 1/2b. Since 1988, the surveillance of listeriosis is computerized using a system of minicomputer terminals (called Minitel) linked via a national telephone network to a large computer. The 70 microbiologists involved in this surveillance must send, on a 24 h basis, data as a soon as they have a new isolate of Listeria monocytogenes in their laboratories. An investigation (typing of the strains, case-control study) is made for each cluster detected.