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Published on: April 29, 2020
Evaluation of the liaison automated testing system for diagnosis of congenital toxoplasmosis
Andrea-Romana Prusa1, Michael Hayde, Arnold Pollak
1Department of Pediatrics and Adolescent Medicine, Division of Pediatric Neonatology, Intensive Care and Neuropediatrics, Medical University of Vienna, Vienna, Austria.
Insights
This study evaluated the Liaison diagnostic system for congenital toxoplasmosis screening in infants. The system demonstrated high specificity and accuracy, aiding in monitoring infants at risk for this infection.
Area of Science:
- Medical Diagnostics
- Immunology
- Infectious Diseases
Background:
- Congenital toxoplasmosis is a global health concern requiring effective infant screening.
- Limited data exists on commercial immunoassays for diagnosing congenital toxoplasmosis in neonates.
Purpose of the Study:
- To assess the performance and analytical characteristics of the Liaison diagnostic system for detecting Toxoplasma gondii antibodies in infants.
- To evaluate the utility of Liaison IgG, IgM, and IgG avidity index for congenital toxoplasmosis diagnosis.
Main Methods:
- A retrospective analysis of 1,157 serum and umbilical cord blood samples from 333 infants (121 infected, 212 non-infected).
- Comparison of Liaison IgG and IgM antibody testing and IgG avidity index against the Sabin-Feldman dye test and immunosorbent agglutination assay-IgM.
Main Results:
- The Liaison system achieved 81.8% sensitivity, 100.0% specificity, and 84.4% overall agreement with the dye test for IgG antibodies.
- IgM testing showed 96.0% overall agreement. Avidity testing did not provide additional diagnostic benefit.
- All non-infected infants tested negative for Liaison IgG within the first year.
Conclusions:
- The Liaison system is a valuable tool for monitoring the serologic status of infants at risk for congenital toxoplasmosis.
- A confirmatory serologic test is recommended to enhance detection rates at one year of age.
- Improved diagnostic tools and follow-up protocols are crucial for better infant care after gestational infections.
Abstract:
Congenital toxoplasmosis is a worldwide health problem, and different screening strategies exist. Testing of toxoplasma-specific antibodies in infants identifies congenital toxoplasmosis during the first year of life. However, experience with commercial available immunoassays is limited. The aim of this study was to evaluate both the performance and analytical characteristics of the Liaison diagnostic system in infants. In a retrospective study, serum Toxoplasma gondii antibodies were measured in samples from 333 infants, including 212 noninfected infants and 121 infants with congenital toxoplasmosis. A total of 1,157 umbilical cord blood and peripheral serum samples were analyzed. Liaison toxoplasma-specific IgG and IgM antibodies and the IgG avidity index were compared to the infection status of the infant, determined by the Sabin-Feldman dye test and immunosorbent agglutination assay--IgM. All noninfected infants were seronegative by Liaison IgG within the first year of life. The Liaison system showed a sensitivity of 81.8%, a specificity of 100.0%, a positive predictive value of 100.0%, a negative predictive value of 90.6%, and overall agreement of 84.4% by comparison with the dye test. Overall agreement of both IgM test systems was 96.0%. In this study cohort, avidity did not show a potential diagnostic benefit for the detection of congenital infection. In conclusion, the Liaison system is a valuable tool to monitor the serologic course of infants at risk. A final serologic confirmatory test is recommended to improve the rate of detection of congenital toxoplasmosis at 1 year of life. Protocols of routine follow-up testing in infants and accurate diagnostic tools after acute gestational infections are needed to improve medical care.
