Table 1.

Ehrlichiosis Case definitions as established by the Council of State and Territorial Epidemiologists[18]

Confirmed Case	Probable Case
Meets clinical evidence and laboratory confirmed criteria	Meets clinical evidence and laboratory supportive criteria
Clinical Evidence
One or more of the following:  ● Fever  ● Headache  ● Myalgia  ● Anemia  ● Leukopenia  ● Thrombocytopenia ● Hepatic transaminase elevation
Laboratory Confirmed	Laboratory Supportive
Serological evidence of a fourfold change in IgG-specific antibody titer to E. chaffeensis antigen by indirect immunofluorescence assay (IFA) between paired serum samples OR Detection of E. chaffeensis DNA in a clinical specimen via amplification of a specific target by polymerase chain reaction (PCR) assay	Serological evidence of elevated IgG or IgM antibody reactive with E. chaffeensis antigen by IFA, enzyme-linked immunosorbent assay (ELISA), dot-ELISA, or assays in other formats* OR Identification of morulae in the cytoplasm of monocytes or macrophages by microscopic examination.

*CDC uses an IFA IgG cutoff of > 1:64 and does not use IgM test results independently as diagnostic support criteria.