New Test for Trachoma Gives More Accurate Results
Rapid dipstick immunoassay better than assessing clinical signs
FRIDAY, May 12 (HealthDay News) -- A new dipstick immunoassay for trachoma used at the point of care (POC) yields more accurate results than the currently used detection method, which relies on clinical symptoms, according to a study published in the May 13 issue of The Lancet.
Claude-Edouard C. Michel, M.Sc., of the University of Cambridge in the U.K., and colleagues compared the performance of the newly developed POC assay, which detects chlamydial lipopolysaccharide, with the presence of trachomatous inflammation-follicular (TF), a clinical sign that doesn't always correlate with C. trachomatis infection. The researchers tested 664 children aged 1 to 9 years in remote Tanzanian villages where trachoma is endemic. All samples were also tested using commercial PCR.
There were 128 cases of ocular C. trachomatis infection detected by PCR. Using presence of TF as a diagnostic tool had 64.1 percent sensitivity, 80.2 percent specificity and positive predictive value of 43.6 percent. The POC assay had a sensitivity of 83.6 percent, specificity of 99.4 percent and positive predictive value of 97.3 percent.
"The POC assay has substantial advantages over the use of clinical signs. If the POC assay was to become widely available at low cost, it could help programs reliably identify communities needing mass treatment with antibiotics," the authors conclude. They also recommend further studies in areas of low, medium and high trachoma prevalence to confirm the performance of the POC assay, as well as research to develop sampling strategies and determine cost-effectiveness.