AIMS: To evaluate the suitability of five commercial assays (Toxoreagent, DA, Captia Toxo IgG, Toxenz-G, Toxonostika-G) for screening large numbers of sera for antibodies to Toxoplasma gondii. METHODS: Sera from 1000 pregnant women booking for antenatal care at a London hospital were screened in parallel by each test. Sera giving discordant results were retested. RESULTS: The Captia Toxo IgG enzyme immune assay gave the best specificity on initial screening, with 0/773 false positives and only 2/218 false negatives. The Toxoreagent latex agglutination test performed well provided sera were tested at several dilutions to prevent prozone effects; 0/218 false negatives (greater than 12 IU/ml). Only one evidently false positive result was seen in the 1000 samples tested. The DA test gave no false negative results but produced 23/773 false positives. After repeat testing there were 9/1000 sera which gave equivocal results which were negative by the Captia Toxo IgG test (less than 12 IU/ml) but with low titres of 16 in the Toxoreagent test or 4 IU/ml in the DA test. In this situation women would have been asked for a follow up sample for repeat testing. Only 300 sera were tested by Toxenz-G; initial screening produced 4/58 false negative results and 4/242 false positives. CONCLUSIONS: The Captia Toxo IgG test gave the fewest discordant results on initial screening. Results could be readily expressed in international units using a programmable plate reader, and this may be useful for epidemiological studies. The Toxoreagent test is considerably cheaper, and is a simple and reliable method for screening provided that at least two dilutions are used.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.