Eperythrozoon ovis, used thought to be a rickettsia but now identified as a mycoplasma, is an erythrocytic agent that causes hemolytic anemia both in animals and human. To demonstrate the epidemiological status of Eperythrozoon ovis infection in Chinese population, 1458 healthy volunteers, 247 patients with hematologic disorders and 106 susceptible people with direct contact to suspected animals were investigated by classical blood smear examination. The positive samples were identified by a specific PCR assay. The microscopic results showed a lot of small organisms attaching on the surface of erythrocytes (Fig 1). The partial 16s rRNA gene of these organisms was amplified using the conserved primers and confirmed as hemoplasma by sequence alignment analysis. Moreover, complement regulatory protein (CR1, CD35), indicating the function of red cell membrane, was tested by flow cytometry with mouse anti-human CD35 and caprine-anti-mouse IgG-FITC reagents. The expression of CR1 might help to elucidate the mechanism why the Eperythrozoon always lead to anemia and icterus in human being (Fig 2).
The Eperythrozoon infection rate in healthy was 239/1458, 95/247 in hematologic disease patients and 55/106 in susceptible people, respectively in our results. Results of flow cytometry in peripheral blood sample showed the co-relation between the CD35 expression and the eperythrozoon infection status.
The CD35 values increased obviously in the infected cases. In the 4 outbreak cases with FUO (Fever of unknown origin, finally diagnosed as eperythrozoonsis), CD35 reached the peak which might indicate the immuno-defense from the body against the hemotrophic mycoplasma. Gradually, the CD35 value decreased markedly in the long-term infectious cases, which may be explained by anemia and icterus resulting from destroyed membrane of the erythrocyte.
Disclosures: No relevant conflicts of interest to declare.