Effect of testing for IgG avidity in the diagnosis of Toxoplasma gondii infection in pregnant women: experience in a US reference laboratory.
The usefulness of testing for IgG avidity in association with Toxoplasma gondii was evaluated in a US reference laboratory. European investigators have reported that high-avidity IgG toxoplasma antibodies exclude acute infection in the preceding 3 months. In this US study, 125 serum samples taken from 125 pregnant women in the first trimester were chosen retrospectively, because either the IgM or differential agglutination (AC/HS) test in the Toxoplasma serologic profile suggested or was equivocal for a recently acquired infection. Of 93 (74.4%) serum samples with either positive or equivocal results in the IgM ELISA, 52 (55.9%) had high-avidity antibodies, which suggests that the infection probably was acquired before gestation. Of 87 (69.6%) serum samples with an acute or equivocal result in the AC/HS test, 35 (40.2%) had high-avidity antibodies. Forty women were given spiramycin, to prevent congenital transmission, and 7 (17.5%) had high-avidity antibodies. These findings highlight the value of testing a single serum sample obtained in the first trimester of pregnancy for IgG avidity.
Liesenfeld
O
O
Department of Immunology and Infectious Diseases, Research Institute, Palo Alto Medical Foundation, Ames Bldg., 795 El Camino Real, Palo Alto, CA 94301, USA.
Montoya
J G
JG
Kinney
S
S
Press
C
C
Remington
J S
JS
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000915:Antibody Affinity; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006386:Hemagglutination Tests; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000175:diagnosis*; D011261:Pregnancy Trimester, First; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014122:Toxoplasma / Q000276:immunology; D014123:Toxoplasmosis / Q000175:diagnosis*; D014481:United States
D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007073:Immunoglobulin E