Rs. Barwick et al., EPIDEMIOLOGIC FEATURES OF EQUINE LEPTOSPIRA-INTERROGANS OF HUMAN SIGNIFICANCE, Preventive veterinary medicine, 36(2), 1998, pp. 153-165
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.