A Proposed Method of Premunizing Cattle with Minimum Inocula of Anaplasma marginale

Previous investigators have shown that only a very minute dose of Anaplasma marginale infected blood is necessary to produce anaplasmosis in a susceptible bovine. The authors summarize earlier data in which a 5 ml. dose of inoculated carrier blood produced a 72% mortality in mature Jersey cows. This data is compared with the current data in which Jersey cows and 18-month-old Herefords were inoculated from the same carrier with 1 ml. doses of blood diluted 10−2 (0.01 ml.) in normal bovine sera. In Jersey cows, without treatment, there was a 12½% mortality. Eighteen-month-old Herefords showed no mortality and little or no clinical symptoms. The authors propose that the “minimum dose” idea of premunizing cattle be tried in the field in areas where premunition is warranted.