Outbreak of cutaneous leishmaniasis amongst militia members in a non-endemic district under conflict in the lowlands of Somali Region caused by Leishmania tropica, Eastern Ethiopia

BACKGROUND: Cutaneous leishmaniasis (CL) in Ethiopia has typically been linked to high-altitude regions but has recently emerged at an unusually low altitude of 500 meters in the Somali Region, raising public health concerns. Cutaneous leishmaniasis has not been previously identified in the region. There is a conflict in the starting area and only militias have been infected with very serious lesions. METHODOLOGY/PRINCIPAL FINDINGS: Routine clinical and socio-demographic information was extracted from the patient chart using a case report form. Additionally, clinical and laboratory data were obtained from 30 patients suspected for CL. Skin scraping and fine needle aspirates were collected from the raised edges, nodular and centre of the lesions followed by DNA extraction using the DNeasy Blood and Tissue kit. There were a total of 1050 CL patients recruited, all of them were male militia members, immunologically naïve and displaced into a conflict area with a likely sylvatic transmission cycle. We identified Leishmania tropica as the causative species, challenging the previous assumption that L. aethiopica was the primary agent of CL in Ethiopia. Notably, over 77% of patients had more than 10 lesions, a presentation atypical for L. tropica elsewhere. Phlebotomus orientalis and P. sergenti, vectors for visceral leishmaniasis and CL in North Africa respectively, were found in the outbreak area. CONCLUSIONS/SIGNIFICANCE: Further research is needed to explore the eco-epidemiology of the outbreak and patient's treatment responses. Insights will help develop management strategies to control this newly emerging form of CL, prevent its spread to other regions and hybridization with Leishmania strains causing VL endemic in the area.