Evaluation of the anaplasmosis rapid card agglutination test for detecting experimentally infected elk.

Anaplasmosis was experimentally transmitted from cattle to elk to cattle. Six non-splenectomized adult elk (Cervus canadensis canadensis) that were inoculated with freshly collected heparinized blood from cattle chronically infected with Anaplasma marginale became asymptomatic carriers. Although the exposed elk did not develop clinical or hematologic evidence of infection they become seropositive by the serum and plasma rapid card agglutination (RCA) tests. Blood from the experimentally infected elk produced disease in splenectomized bovine calves and the carrier state persisted for at least one year. Infection did not occur when two elk were inoculated with 0.5 ml of frozen blood from known bovine carriers. The blood had been frozen for four weeks in liquid nitrogen with six percent dimethyl-sulfoxide.