Newly recognized Anaplasma sp. in erythrocytes from Gopher Tortoises (Gopherus polyphemus).

BACKGROUND

In 2015, a previously unrecognized intracytoplasmic erythrocytic inclusion was discovered in anemic wild-caught adult gopher tortoises (Gopherus polyphemus). Subsequently, molecular diagnostics revealed this inclusion to be a novel Anaplasma sp.

OBJECTIVES

The goal of this study was to morphologically characterize these erythrocytic inclusions by light and transmission electron microscopy (TEM).

METHODS

Blood samples were taken from two car-injured wild-caught gopher tortoises for the preparation of Wright-Giemsa stained smears and TEM specimens. CBC data were serially performed and morphologically examined during treatment periods.

RESULTS

Studies revealed a moderate to severe anemia with moderate regeneration as indicated by polychromasia and the presence of immature erythroid precursors. In addition, on light microscopy, one to two variably-sized round basophilic stippled paracentral erythrocytic inclusions were present per cell in both animals and involved 10%-25% of erythrocytes. TEM identified the intraerythrocytic inclusions as discrete membrane-bound cytoplasmic vacuoles (morulae) containing membrane-bound bacterial subunits that were of variable size, shape, and electron density. Serial hematologic data indicated complete remission of the infection in response to a single long-term course of doxycycline.

CONCLUSIONS

The presence of a regenerative anemia in gopher tortoises from Florida revealed a newly recognized bacterial species that has morphologic characteristics similar to members of the genus Anaplasma.