Leptospirosis in rodents from an arid environment.

Rodents (n = 358) were trapped from 6 locations in Arizona, including 2 dairies, 2 swine raising operations, and 2 areas where domestic animal access was limited. Isolates of Leptospira interrogans serovar ballum were obtained from 3 house mice (Mus musculus) trapped in dairies. Leptospira were seen in silver-stained kidney sections of 10.4% of the rodents. The usefulness of serologic data in detecting leptospiral infection in these rodents was uncertain because so few animals yielded isolates that valid comparisons of culture positives to serologic positives were not possible. Titers greater than or equal to 1:160 were obtained to serovars autumnalis, ballum, bratislava, canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona. Nearly 60% of the rodents had microscopic lesions in kidneys, including 20 of 34 (59%) of those in which leptospira were seen.