A serologic survey of human and bovine leptospirosis associated with dairy farms in northeast Texas

Vita.A serologic survey was conducted using a defined segment of the cattle and human populations of 12 dairy farms located within 8 counties in Northeast Texas. Leptospira serologic titer distribution and intensities of 25 serovars were examined for both populations to determine: (1) the apparent serologic titers to prevalent Leptospira serovars within the dairy cattle populations; (2) to determine the relation, if any, of these serovars to the serologic titers to Leptospira serovars observed in the personnel associated with the dairy cattle; (3) to determine if there exists a greater prevalence of significant Leptospira serologic titers in humans associated with dairy farms in Northeast Texas than in comparable populations whose vocations are non-farm animal oriented. One hundred and forty-nine (89.2%) of the 167 dairy cattle tested had serum titers to one or more Leptospira serovar. Twenty-four of the 25 possible serovars were observed at least once in the 372 dairy cattle serums (54% paired serum samples). Serum titers ranged from 1:50 to 1:12800 with the highest titers occurring in the canicola and butembo serovars. Titers to the pomona, wolffi, and icterohaemorrhagiae serovars were the most prevalent (36.5%, 41.2%, and 55.7% respectively). No significant differences were observed between the above dairy population and data obtained from the serologic profiles to Leptospira of 294 cattle slaughtered at a local abattoir.