Same Old Bugs, New Diseases

Blood-borne mycoplasmas, known collectively as hemotropic mycoplasmas or hemoplasmas, are small, pleomorphic, epicellular bacteria that adhere to the host’s red blood cells. They cannot be cultured. They can be detected microscopically in blood smears and, more reliably, through use of PCR assays on whole blood. The hemoplasmas vary in severity of disease caused to the host and most infected animals appear healthy. Concurrent infections, stress, and immunosuppression may induce signs of disease that include fever, lethargy, anorexia, and mild to severe anemia. Severe forms of disease are characterized by hemolytic anemia, which can be treated with antibiotics and blood transfusions. Although often effective at eliminating signs of disease, treatment is not likely to completely clear hemoplasmas from the body and the infected animal remains a carrier. Transmission of hemoplasma is by arthropod vectors, blood transfusions, common use needles and surgical instruments, and, possibly, by animals fighting with each other. Vertical transmission from mother to offspring occurs with several of the hemoplasmas. The focus of this presentation will be hemoplasmas of large animals and will include Mycoplasma wenyonii (formally Eperythrozoon wenyonii) and Mycoplasma hemobos of cattle, Mycoplasma ovis and Mycoplasma hemovis of sheep, and hemoplasmas of horses and deer. Before that discussion begins, it is important to consider the hemoplasmas as potential zoonotic agents. Recent reports listed below are examples of human infection with animal hemoplasmas.