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

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 w 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.