title: Recent primary toxoplasma infection indicated by a low avidity of specific IgG.
abstract: An unusual assay was developed for the serologic diagnosis of recent primary infection by Toxoplasma gondii. This test measures the antigen-binding avidity of toxoplasma-specific IgG antibodies. Serum samples from 5 patients with recent primary toxoplasma infection were compared with those from 21 subjects with preexisting toxoplasma immunity. Patients with primary infection exhibited a low avidity of toxoplasma-specific IgG, which persisted for several months after the onset of symptoms of toxoplasmosis. In contrast, all subjects with past immunity had a high avidity of toxoplasma-IgG. This IgG avidity assay should assist in the diagnosis of acquired toxoplasmosis and may be used to identify pregnancies that are at risk for congenital toxoplasmosis.
authors.affiliation: Department of Virology, University of Helsinki, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Hedman
authors.forename: M
authors.initials: M
authors.lastname: Lappalainen
authors.forename: I
authors.initials: I
authors.lastname: Seppäiä
authors.forename: O
authors.initials: O
authors.lastname: Mäkelä
mesh_terms: D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000915:Antibody Affinity; D000918:Antibody Specificity; D000953:Antigens, Protozoan / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology*; D012008:Recurrence; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000175:diagnosis* / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007106:Immune Sera; D007074:Immunoglobulin G