Leptospira interrogans serovar hardjo infection of cattle.

A survey of normal cattle in the Southern Victorian statistical divisions revealed that microscopic agglutination titres to L. hardjo occur at high frequency and are distributed throughout the cattle population. These titres are difficult to interpret as they may represent recent or old exposure, with or without disease. L. hardjo infection of dairy cattle was studied in 4 herds using the microscopic agglutination and complement-fixation tests. Statistical comparisons of individual titres obtained indicated that the sensitivity of the complement-fixation test was satisfactory for diagnostic purposes, but the test was unable to differentiate between current or past infections.