Use of a clinical tool for screening and diagnosis of cutaneous leishmaniasis in Sri Lanka

Abstract

Cutaneous leishmaniasis (CL) was first detected in Sri Lanka in 1992.Local disease is caused by a genetically different variant of Leishmania donovani. Early case detection and management is the mainstay of L. donovani control. High degree of clinical suspicion is critical but a clinical diagnostic tool is not available for leishmaniasis. Current study described, for the first time, a two-staged clinical algorhythm that facilitates screening of CL in Sri Lanka by primary health care worker in stage 1 and management by medical professional in stage 2.Selected clinical markers of 400 patients suspected of CL were analysed retrospectively with laboratory confirmation of leishmaniasis. Ten clinical markers predicted CL with a over 90% accuracy. Subsets of markers showed high levels of sensitivities (60–97.2%) and/or significant association with positive laboratory results as compared to negative lesions [typical onset (acne-form, painless non-itchy), (P = 0.026), size up to 2 cm (P = 0.046), well-defined edges (P = 0.002), regular edges (P = 0.018), rounded shape (P = 0.030), and lesions at 5–8 months (P = 0.052)]. Five of them (typical onset, number up to 2, small size, rounded edges, and rounded shape) also had > 70% sensitivity levels as compared to laboratory findings. Typical onset had the highest sensitivity of 97% and a PPV of 72%. Lesions at 5–8 months duration having defined edges (P = 0.013, specificity 89.7%, PPV 83.1) or having regular edges (P = 0.006, specificity 86.2%, PPV 82.4%) were also predictive of CL. Most of early laboratory-confirmed ( < 12 months) lesions remained  < 3 cm (sensitivity > 67%, PPV > 70%) and had defined edges (sensitivity of 52–71%, specificity 46.7–68.8%), (PPV 75.1–86%). Four clinical markers served as good diagnostic markers in both early ( ≤ 4) and late (>12 months) lesions, viz. typical onset (91.3–98.4%), presence of ≤ 2 lesions (sensitivity 82.6–94.7%), size ≤ 2 cm (66.9–73.7%), and regular edges (68.6–76.3%). Reliability of clinical markers generally declined in chronic lesions. However, small lesions of over 12 months were highly indicative of CL (sensitivity of 66%, specificity 66.7%). None of the single/combination markers, however, were 100% sensitive or specific, highlighting the undeniable usefulness of laboratory confirmation, in diagnosis. Decision-making algorithm used 10 basic clinical features for screening and seven specific clinical markers for clinical handling and referral for investigations.