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
On approximately July 1st, 1961, twenty-seven Wyon1ing cows with calves were shipped into North Central Iowa. Upon arrival, the cows and calves were turned out to pasture. Approximately a month and a half later, one of the cows appeared rather weak, depressed and mildly icteric. She died twelve hours after onset of the symptoms. Within the next few days, several other cows began to show similar symptoms of anemia, Iowa State University Veterinarian weak11ess and icterus, with one of the animals becoming belligerent. None of the calves were affected.
"Anaplasma Marginale Infection in the Bovine,"
Iowa State University Veterinarian: Vol. 24
, Article 11.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol24/iss1/11