EPIDEMIOLOGIC FEATURES OF EQUINE LEPTOSPIRA-INTERROGANS OF HUMAN SIGNIFICANCE

Leptospirosis is a zoonotic bacterial disease caused by Leptospira int errogans, There is a serologic evidence that horses are exposed to L. interrogans and, as a shedder of these organisms, can be a threat to h umans. We examined risk factors associated with the risk of testing se ropositive to three L. interrogans serovars (L. icterohaemorrhagiae, L . grippotyphosa, and L. canicola) in the horses of New York State, in order to understand the epidemiology of the disease and suggest strate gies to control and prevent equine leptospirosis. To carry out this st udy, blood samples were collected from a random sample of 2551 horses and tested for the presence of antibodies to the above serovars using the microscopic agglutination test. Samples with a titer $100 were con sidered positive. Clinical and demographic data were collected on each horse, the farms' management practices and ecology. Logistic regressi on analysis was used to develop a multivariate indexing system and to identify factors significantly associated with the risk of leptospiros is. Four indices were developed based on the possible sources of expos ure: rodent exposure index; wildlife exposure index; soil and water in dex; and management index. The soil and water index was significantly associated with the risk of exposure to all three serovars. Management was positively associated with L. icterohaemorrhagiae and L. canicola . Density of horses turned out together was positively associated with the risk of exposure to L. grippotyphosa, We concluded that indirect exposure of horses to L. interrogans through contaminated soil and wat er appears to be significantly associated with the risk of exposure to all three serovars. Management appears to play an important role in t he exposure to L, interrogans. Modification of management practices mi ght reduce the horses' risk of exposure and hopefully minimize the hum an hazards. (C) 1998 Elsevier Science B.V.