The following blood sample belongs to a cow from a beef herd in northeast Oklahoma with history of weight loss, icterus and hemoglobinuria. Eight of 140 animals died with no previous symptoms.
Image 1: Blood smear from a cow.
Anaplasma marginale is a tick transmitted pathogen which causes hemolytic anemia in cattle. In the US is mainly transmitted by the Dermacentor spp. ticks, however it can also be transmitted mechanically via biting flies, mosquitoes and contaminated fomites. Cattle infected with A. marginale show symptoms such as fever, abortion, icterus, weight loss and in some instances mortality. The morulae of A. marginale are found in erythrocytes of acutely infected cattle.
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