A STUDY ON THE PREVALENCE OF CUTANEOUS  LEISHMANIASIS: CAUSATIVE SPECIES, SAND FLY VECTORS AND ANIMAL RESERVOIRS IN HAMBANTOTA DISTRICT, SRI LANKA

Cutaneous leishmaniasis (CL) is an established disease in the country. Present study was  designed to investigate distribution, epidemiological features and clinical manifestations,  identification of vectors and reservoir hosts of CL in Hambantota district, which is an endemic area for the disease. Patients who presented to either Tangalle or Hambantota hospitals from March, 2014 to February, 2017 were participated in the study. After a complete clinical examination was performed on each patient, a descriptive study was  carried out using an interviewer-administered questionnaire. Slit-skin smears were taken from lesions and stained with Giemsa and examined under a light microscope to identify Leishmania amastigotes. Appropriate SPSS and Minitab tests were performed to analyze  collected data. Out of 804 CL suspected patients, smears of 604 patients were positive for  Leishmania sp. District Secretary Divisions with the highest number of CL cases were Tangalle, Beliatta and Ambalantota respectively. Majority of patients were ≥ 50years  (p < 0.001) with more males (60.3%) than females (39.7%). Students (20.5%) and house wives (20.6%) were more common among patients. Most of them had single lesion on their arms (N = 318). Size, duration and characteristics of CL lesions were also analyzed. More CL cases were reported in March, May, August, and October in 2014 and January to March in 2015. Histopathology of lesions were studied taking skin biopsy samples  (N = 45) from patients and Haematoxyline/Eosin stained sections were prepared. Dermal and epidermal changes were observed in these sections and large number of amastigotes was present in lesions < 6 months old and in older lesions they had spread to deeper layers of the skin. LITSR-PCR and RFLP were performed using thick lesion smears of CL  patients and Leishmania donovani as the causative organism of CL in this study area was confirmed. Biting midges (358) and 120 sand flies were collected from ten households of patients  using CDC light traps with Castor oil paper strips. Sand flies belong to three Phlebotomus spp. including P. argentipes and five Sergentomyia species were identified and S. clydei was common. Three sibling species of P. argentipes complex were separated using principal component analysis. Blood samples were collected from dogs (N = 56), a cat and rodents (Mus mayori, N = 8) found in peri-domestic areas of selected CL patients. Buffy  coat was separated and PCR was performed with two primers kDNA and ITS1, LITSR separately. All samples were negative for the parasite. Collected information with the questionnaire was analyzed to identify possible risk factors for increasing of CL cases in the area. Socio demographic factors were age, sex, occupation of patients, living in old houses and possible life- style factors were usage of non-impregnated bed nets (75.50%), lacking of insecticide spraying, outdoor activities and  rearing animals. Presence of earlier infected CL patients, dumping garbage and waste water to the open land and having unutilized lands and shrub jungles very close to their  houses were possible peri domestic environmental factors. Lack of awareness on sand flies and their biting is also noted. Present findings indicate that an anthroponotic transmission of Leishmania parasites may be persisting in study sites of Hambantota district. Further studies on transmission of L. donovani are needed to control CL in this endemic region.