Table 2.
Case definition | Laboratory test result |
---|---|
Supportive HGA | Morulae present in peripheral blood smear neutrophilsa or |
Single serum A. phagocytophilum IgG titer by IFAb ≥ 640 | |
| |
Confirmed HGA | A. phagocytophilum IFA IgG seroconversion d or |
Positive A. phagocytophilum PCRc of blood or | |
Isolation of A. phagocytophilum from bloode or | |
A. phagocytophilum antigen present in tissue sample by immunohistochemistry |
Definitions are dependent upon a presentation with manifestations clinically-consistent with HGA.
Light microscopy of Wright stained peripheral acute phase blood;
Indirect immunofluorescent antibody test with A. phagocytophilum antigen;
Polymerase chain reaction with specific A. phagocytophilum primers;
Fourfold or greater change in serum antibody titer;
Isolation of A. phagocytophilum from blood incubated in HL-60 human promyelocytic cell line.