Positivity of the anti-PGL-I rapid test in clinically difficult-to-manage situations in leprosy: evidence from a Brazilian reference center

Abstract

Introduction: leprosy remains a significant public health problem in Brazil, with complex clinical situations that frequently challenge conventional diagnostic and therapeutic management. Objective: to evaluate the positivity of the rapid anti-phenolic glycolipid I test in patients attended at a reference service classified into four difficult-to-manage situations: suspected or confirmed relapse, therapeutic failure, difficult-to-control lepra reaction, and difficult leprosy diagnosis. Methods: cross-sectional study conducted with 23 adult patients, predominantly multibacillary, attended at a reference service. Results: the rapid test was reactive in 15 cases (65.2%). Among patients with suspected or confirmed relapse, the test was positive in six of nine cases, assisting in diagnostic reassessment, including one case with negative conventional tests. In cases of difficult-to-control lepra reaction, three of five patients had a reactive result, helping to confirm underlying bacillary activity. In difficult diagnostic cases, the test was positive in four of seven patients, prompting repeat biopsy with diagnostic confirmation in two cases and supporting the treatment initiation in two others. In both cases of suspected therapeutic failure, the test was reactive, corroborating the maintenance of serological activity. Discussion: the findings demonstrate that the rapid test can serve as a relevant complementary tool, especially in scenarios where conventional examinations are inconclusive or insufficient to guide clinical management. Conclusion: the rapid anti-phenolic glycolipid I test proved useful in the management of complex leprosy situations and should be interpreted in an integrated manner alongside clinical evaluation and available conventional examinations.