Ehrlichia chaffeensis (HME) Antibody, IgG and IgM, IFA

This test is used for detection and semiquantitation of serum IgG and IgM antibodies to Ehrlichia chaffeensis to aid in the diagnosis of human monocytic ehrlichiosis (HME).

Confirmation of diagnosis is based on laboratory testing, but antibiotic therapy should not be delayed in patients with a suggestive clinical presentation. The diagnosis of acute ehrlichiosis cannot be confirmed solely by the presence of antibodies in a serum sample collected at a single timepoint. DNA PCR can be used to diagnose acute infection. Demonstration of a 4-fold rise in IgG-specific antibody titers by IFA in paired samples (acute and convalescent) confirms infection with E. chaffeensis. IgM antibodies are less specific than IgG antibodies and are more likely to generate false positive results. IgM results alone should not be used for laboratory diagnosis. Antibody titers are frequently negative during the first 7-10 days of illness.