Babesia microti Antibodies, IgG and IgM

This test is a screening assay for Babesia microti infection or exposure.

Serological testing for antibodies to Babesia microti (B. microti) can provide evidence to support a diagnosis of babesiosis. Serology should not be used for routine diagnosis of acute babesiosis, as it is difficult to distinguish active from past infection using serology alone. A B. microti IgG antibody titer of greater than or equal to 1:1024 or the presence of B. microti IgM antibody are suggestive of active or recent B. microti infection, while a 4-fold rise in Babesia IgG antibody in sera from the time of acute illness to the time of convalescence confirms the diagnosis. Individuals positive for B. microti antibodies should have confirmatory testing performed by PCR or peripheral blood smear before treatment is considered. The diagnosis of acute babesiosis cannot be confirmed solely by the presence of Babesia antibody in a serum sample collected at a single time point. Babesiosis coinfection should be considered in Lyme disease patients with severe illness, in those whose symptoms are unlikely to be explained by B. burgdorferi infection alone, or in those who do not respond well to standard antibiotic therapy for Lyme disease.