Evaluation of point-of-care tests for cutaneous leishmaniasis diagnosis in Kabul, Afghanistan

Abstract

Background: Kabul (Afghanistan) is a major focus of cutaneous leishmaniasis (CL) caused by Leishmania tropica. Microscopy remains the reference test for diagnosis despite its low performance. We evaluated whether Loopamp™ Leishmania Detection Kit (Loopamp) and CL Detect™ Rapid Test (CL Detect), detecting Leishmania DNA and antigen, respectively could improve CL diagnosis.

Methods: A diagnostic accuracy study with prospective inclusion was conducted in a leishmaniasis reference clinic in Kabul. Slit skin samples from CL suspects were analysed by microscopy. Samples taken with a dental broach were tested with CL Detect, Loopamp, and PCR. All samples were transferred to the Academic Medical Center (AMC, the Netherlands) for PCR and Loopamp analyses. The diagnostic performance of the tests was evaluated against a reference combining microscopy and PCR.

Findings: 274 CL suspects were included in the study. In Kabul, CL Detect had a 65·4% sensitivity [95% Confidence Interval (CI): 59.2-71.2%] and a 100% specificity [95% CI: 80.5-100%], while these were 87.6% [95%CI: 82.9-91.3%] and 70.6% [95% CI: 44.0-89.7%] for Loopamp. At AMC the Loopamp's sensitivity (92.2% [95% CI: 88.2-95.2%]) and specificity (94.1% [95% CI: 71.3-99.8%]) were higher. An algorithm where CL Detect negative suspects would be tested by Loopamp yielded a 93.4% sensitivity [95% CI: 89.6-96.1%] and a 94.1% specificity [95% CI: 71.3-99.8%] when Loopamp's performance at AMC was used.

Interpretation: The high specificity of CL Detect and the performance of Loopamp allow their use in a diagnostic algorithm that would minimize the number of CL patients referred for confirmation. FUND: Federal Ministry of Education and Research, Germany.