Introduction: Soil-transmitted helminth infections are considered a public health problem in developing countries. The diagnostic tests, both for individual parient diagnosis as for population studies should be evaluated in terms of validity and reliability.
Objective: To compare the direct examination, the modified Ritchie-Frick method, a Kato-Katz designed by a Brazilian group and one designed by the WHO, for the diagnosis of soil-transmitted helminthes.
Materials and methods: A diagnostic test reliability study was performed. The same stool sample was analyzed by the same observer using four diagnostic tests. 204 samples were obtained, 194 of those fulfilled the inclusion criteria and were analyzed. The observers did not know the participants' identity neither the other tests results. For the analysis the Kato-Katz (WHO) was considered as the gold standard. For the reliability assessment percent agreement, positive percent agreement, Kappa statistic, and intraclass correlation were performed.
Results: The Brazilian Kato-Katz showed a good performance with high sensitivity and specificity for T. trichiura and Hookworm with values of 0.97 and 0.96 respectively, and a high specificity with mild sensitivity for A. lumbricoides (0.95 and 0.79) meanwhile the direct examination and the Ritche-Frick method showed a performance between mild and poor. The differences were higher for hookworm and Trichiuris trichiura than for Ascaris lumbricoides.
Conclusion: The Brazilian Kato Katz test could be implemented, but further studies are needed to correlate its operative capacity with its feasibility, availability and cost.