Bovine Leptospirosis and Its Control

Abstract

Leptospirosis is a disease of cattle which varies from an inapparent to an acute fulminating disease in some cattle. Most livestock owners only associate leptospirosis with abortions and stillbirths. However, as with many diseases, the overt signs vary with age and physiologic state of the affected animals and the pathogenicity of the agent.

In the United States, six serotypes, pomona, hardjo, szwajizak, grippotyphosa, canicola, and icterohaemorrhagiae have been isolated from cattle (3, 6, 11, 22, 24, 28). All belong to separate serogroups except hardjo and szwajizak which are members of the hebdomadis serogroup and, therefore, are difficult to distinguish between serologically. Several other serotyps have been detected serologically only in U.S. cattle; Serologic testing involving reports from 20 diagnostic laboratories and 66,22 sera from 18 states gave reactor rates of 7 .2% for hardjo end 6.5% for pomona (7). These two serotypes are apparently transmitted directly from cow to cow in most cases while grippotyphosa, canicola, and icterohaemorrhagiae, which are of lower incidence (0.7% to 1.4%) are extensions of infections from wildlife (2,21). However, once the less common serotypes become established in a herd, they can become a major herd disease problem (11,28).