Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Bovine leptospirosis is one of the major cattle diseases in the United States causing significant economic losses to the cattle industry. This disease in cattle has been associated with abortion, repeat breeding, still-births, fetal death,s weak calves, and reduced milk production. In the United States, the disease is cause dby infection with one or more of 6 known pathogenic leptospiral serovars: pomona, hardjo, grippotyphosa, canicola, icterohaemorragiae, and szwajizak.
Nervig, R. M.; Beran, C. W.; and Hill, H. T.
"Bovine Leptospirosis in Iowa: A Serological Survey,"
Iowa State University Veterinarian: Vol. 42
, Article 3.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol42/iss2/3