Prevalence of leptospiral titres in normal horses.

Serum samples were collected from 479 clinically normal horses from 11 different locations in Queensland. Using a microscopic agglutination test, 157 serums (33%) reacted to one or more serovars of Leptospira interrogans at a minimum serum dilution of 1/30. The prevalences of reactors among all horses to the serovars tested were pomona 30.5% icterohaemorrhagiae 23.9%, tarassovi 18.8%, hardjo 12.2%, canicola 8.6%, grippotyphosa 3.6%, and australis 2%. There was a significantly higher prevalence of reactors in tropical areas than in sub-tropical areas, but no difference in prevalence between coastal and non-coastal areas.