Legionella pneumophila Antibody (IgG), IFA

Laboratory assay overview

Legionella infection is associated with 2 clinically and epidemiologically distinct illnesses, Legionnaires' disease and Pontiac fever. Legionnaires' disease is characterized by fever, cough, myalgia, and pneumonia, whereas, Pontiac fever is a milder illness without pneumonia. Inhaling aerosols of water contaminated with Legionella species is believed to be the primary mode of infection; the incubation period is generally 2-10 days. The assays performed detect antibodies to Legionella pneumophila serogroups 1-7. An IgM titer >1:256 provides presumptive evidence of infection at an undetermined time. A 4-fold rise in IgG titer to ≥1:256 between acute and convalescent sera may be used in the laboratory confirmation of Legionella infection with these serogroups of L. pneumophila.