Ehrlichia IgG

In season: 3-5 Days

Off season: 3-8 Days

• Tick-Borne Illness Panel (see the table) as the preferred laboratory test for tick-borne infections in North Carolina. The panel order includes tests for IgG antibody to Ehrlichia chaffeensis, IgG antibody to Spotted Fever Group Rickettsia and total antibody (IgG and IgM) to Borrelia burgdorferi. These tests will use current methodology in the Clinical Immunology Laboratory. This panel is offered in response to evolving epidemiology of tick-borne infections and to promote appropriate testing (see Brown-Marusiak. 2022. JAMA Netw Open). The panel is the preferred order for patients with suspected tick-borne infection although each test can be ordered individually.
• Results of single serological test cannot be used to confirm diagnosis without a paired convalescent result obtained 2-6 weeks later. For suspect patients with new onset symptoms (i.e., fever, headache, myalgia, fatigue) and typical laboratory abnormalities (e.g., leukopenia, thrombocytopenia, or elevated transaminase levels), consider Ehrlichia PCR testing.
• Ehrilichia acute samples will be tested for IgG antibody at a 1:128 dilution and reported as positive (>1:128) or negative (<1:128). Acute samples will not have an endpoint titer determined unless a convalescent sample (collected 2 to 3 weeks after the acute sample) is received. Upon receipt of a convalescent sample both the acute and convalescent samples will be titered to endpoint in order to assess seroconversion or the presence of a four-fold increase in titer which indicate recent infection.

If acute ehrlichiosis is suspected, Ehrlichia PCR is recommended within 7 days of symptom onset.