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The United Kingdom National External Quality Assessment Service for parasitology: toxoplasma serology scheme
  1. Monika M Manser1,
  2. Jean Chatterton2,
  3. Janet Francis3,
  4. Edward Guy3,
  5. Rick Holliman4,
  6. Darrel Ho-Yen2,
  7. Julie Johnson4,
  8. Peter L Chiodini1
  1. 1UKNEQAS Parasitology, Department of Clinical Parasitology, Hospital for Tropical Diseases, London, UK
  2. 2Scottish Toxoplasma Reference Laboratory, Raigmore Hospital, Inverness, Scotland, UK
  3. 3Toxoplasma Reference Unit, NPHS Microbiology Swansea, Singleton Hospital, Sgeti, Swansea, UK
  4. 4Department of Medical Microbiology, St George's Hospital and Medical School, London, UK
  1. Correspondence to Professor P L Chiodini, Department of Clinical Parasitology, Hospital for Tropical Diseases, Mortimer Market, Capper Street, London WC1E 6AU, UK; peter.chiodini{at}


Aim To examine performance in the UK National External Quality Assessment Scheme (UKNEQAS) for toxoplasma serology for evidence of discrepant results as compared with the predistribution and postdistribution results supplied by the toxoplasma reference laboratories.

Methods Analysis of performance in the toxoplasma IgG and IgM schemes was made for the period 1994–2008 to look for trends in performance.

Results For the IgG scheme, a mean of 98% of participants obtained the correct result for detection of toxoplasma-specific antibody. The most common problem was failure to detect low levels of antibody. In some cases this was the result of participants deviating from the manufacturer's instructions and using higher cut-off levels. For the IgM scheme, an average of 95% of participants obtained the correct result for toxoplasma antibody detection. The most common problem was the failure of some enzyme immunoassay kits to detect specific toxoplasma IgM antibody, which was detected by the more sensitive immunosorbent agglutination assay.

Conclusions Performance standards in the UKNEQAS toxoplasma serology schemes were high. The problems encountered have highlighted the importance of detecting low levels of antibody, adhering to the kit manufacturer's instructions and selecting an appropriate assay for the clinical situation.

  • Assays
  • performance
  • quality assurance
  • serology
  • toxoplasma
  • toxoplasma serology

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  • Funding Professor Chiodini is supported by the UCL Hospitals Comprehensive Biomedical Research Centre Infection Theme.

  • Competing interests None to declare.

  • Provenance and peer review Not commissioned; externally peer reviewed.