An Investigation of Possible Wild Animal Hosts of Leptospires in the Area of the ”Fort Bragg Fever“ Outbreaks

Abstract

A total of 89 wild animals including 41 foxes, 22 raccoons, 3 opossums, 3 rabbits and 20 rodents were trapped over a wide area of the Fort Bragg military reservation including the section where human cases of leptospirosis occurred during 1942-1944. Leptospires were isolated from 10 (11.790 of the 84 animals on which cultures were considered satisfactory. Histopathological study of silver-stained kidney sections revealed leptospires in only 4 of the culturally positive animals and in none that yielded negative cultures. Agglutination and agglutinin-absorption studies indicate that 3 of the isolations belong to the L. australis, group and that 7 are members of the L. grippotyphosa serogroup. Gray foxes have not been reported previously as hosts of members of these 2 serogroups in the U. S., nor has the red fox been reported to habor leptospires previously in this country. Agglutination tests on serums from these 89 animals revealed titers in the culturally positive animals ranging from 1:64 to 1:4096 against either L. australis or L. grippotyphosa antigens with one exception. Serums from 2 animals showed low titers with L. ballum and L. pyrogenes antigens.