Strategies for detecting toxoplasma immunity.
A strategy for identifying toxoplasma immunity in pregnancy must provide good evidence of immunity but not falsely reassure; that for immunocompromised patients should identify immunity and also the risk of reactivated toxoplasmosis. Using sera from both of these patient groups, the performance of an in-house IgG EIA and two commonly used commercial assays (Abbott AxSYM Toxo-G and Eiken latex test) were compared with the dye test. False-positive results were obtained using the IgG enzyme immunoassay (EIA) and AxSYM Toxo-G, and false negatives using all three screen tests. During pregnancy, positive results may falsely reassure, and patients should be tested for toxoplasma-specific IgM to differentiate between current infection and immunity. In immunocompromised patients, positive results indicate immunity but negative results do not exclude it; these should be tested by dye test. Despite these reservations, we have demonstrated that immunity screening can be performed within a district general hospital.
Ashburn
D
D
Scottish Toxoplasma Reference Laboratory, Microbiology Department, Raigmore Hospital, Inverness 1V2 3UJ. microbiology@haht.scot.nhs.uk
Evans
R
R
Chatterton
J M W
JM
Joss
A W L
AW
Ho-Yen
D O
DO
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007124:Immunoenzyme Techniques / Q000379:methods; D007074:Immunoglobulin G / Q000097:blood; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000276:immunology*; D014122:Toxoplasma / Q000276:immunology*; D014123:Toxoplasmosis / Q000276:immunology*
D000913:Antibodies, Protozoan; D007074:Immunoglobulin G