Contribution à l'étude épidémiologique des infections à Yersinia enterocolitica. II. - Enquêle écologique

The authors considering the rarity human and animal isolates of Yersinia enterocolitica in France, compared to the high incidence of this infection in others european countries, searched for the possible reservoir of the bacteria. A preliminary study on small mammals caught in two distant areas (Alsace and Indre) has permit to isolate Y. enterocolitica from the spleen of wild field and wood rodents. These encouraging results led us, since January 1975, to a prospective investigation wich dealt in the first hand with the geographical distribution in France of the small mammals carriers of Y. enterocolitica and with the aspect of the infection in the investigated areas (the West, the Center and the North-West of France) and in the second hand with the census of the different wild species carrying Y. enterocolitica in two areas, the middle-West (Indre) and the East of France (Alsace) where through regular trapping, it was possible to estimate the seasonal incidence of the infection among small mammals. The results show that Y. enterocolitica is frequently present in wild mammals and also in water and fishes. This is perhaps an important, but unknown, source of contamination. The relationship between the infection in healthy carriers and the typical infectious disease due to Y. enterocolitica is questionned. The survey of human in those areas where small mammals carrying Y. enterocolitica were found, has already permit to isolate human strains of Y. enterocolitica similar to those isolated from small mammals caught in the same area. This finding allow us to reconsider the epidemiology of Y. enterocolitica infection in discrimating the wild strains isolated among healthy carriers and the strains commonly isolated during typical syndroms. The difference between those two kinds of strains is in opposition with the idea of direct contamination from one host to another, except if we admit the possibility of changes in the biochemical and serological characters of the strains.