GRANULOCYTIC EHRLICHIOSIS IN THE LABORATORY MOUSE

C3H mice that were inoculated with ehrlichiae isolated from a patient with human granulocytic ehrlichiosis (HGE) developed anemia and leukop enia, but by day 24, they returned to normal values. Granulocytic moru lae were present in peripheral blood and spleen smears on days 5 and 1 0, and there was a reduction in morulae on day 17. Ehrlichiae mere pre sent in HL-60 cell cultures of blood and spleen from all mice at all i ntervals. Pathogenicity, but not infectivity, waned with mouse passage but could be resurrected by SCID mouse passage. Various methods were tested for their relative sensitivity in detecting infection: blood sm ears, HL-60 cell cultures, polymerase chain reaction (PCR) amplificati on of a 16S recombinant DNA target, and a mouse infectivity assay, All assays detected the HGE agent in blood during early infection, but PC R and the mouse infectivity assay were most sensitive during late infe ction. Xenodiagnosis demonstrated that mice remain persistently infect ed through 55 days.