title: Differential agglutination test for diagnosis of recently acquired infection with Toxoplasma gondii.
abstract: We evaluated the recently described differential agglutination test (HS/AC test) to differentiate recently acquired toxoplasma infections from those acquired in the more distant past in sera obtained from 38 patients with carefully defined symptomatic and asymptomatic infections. AC antigens detect acute-phase-specific immunoglobulin G (IgG) antibodies against Toxoplasma gondii tachyzoites that are formed only during the acute stage of infection in humans. The HS/AC test correctly identified recently acquired infections in patients with toxoplasmic lymphadenopathy or asymptomatic infections (including infections in 7 women who seroconverted during gestation) in 31 of 33 patients. We also studied 15 individuals who had been infected for at least 2 years. In that group, only 13% had an acute pattern in the HS/AC test. However, the wide range in times from infection (from 2 to 14 years) did not allow for an estimate of when the pattern in the HS/AC test changed from acute to not acute. These results reveal that in the appropriate clinical situation, when both IgG and IgM tests are positive and a question still remains about the acuteness of infection, the HS/AC test may be useful for differentiating between toxoplasma infections acquired recently and those acquired in the more distant past.
authors.affiliation: Department of Immunology and Infectious Diseases, Palo Alto Medical Foundation, California 94301.
authors.forename: B R
authors.initials: BR
authors.lastname: Dannemann
authors.forename: W C
authors.initials: WC
authors.lastname: Vaughan
authors.forename: P
authors.initials: P
authors.lastname: Thulliez
authors.forename: J S
authors.initials: JS
authors.lastname: Remington
mesh_terms: D000372:Agglutination Tests; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis / Q000276:immunology; D013997:Time Factors; D014122:Toxoplasma / Q000276:immunology; D014123:Toxoplasmosis / Q000150:complications / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D007075:Immunoglobulin M