Clinical and epidemiological studies on the cutaneous leishmaniasis caused byLeishmania(Leishmania)donovaniin Sri Lanka

Abstract

Sri Lanka is the newest reported focus of human leishmaniasis within the Indian subcontinent. Over the last 8 years, more than 2000 cases of cutaneous leishmaniasis (CL), apparently caused by Leishmania donovani (a species usually associated with the visceral form of the disease), have been passively identified in the country. The clinical profiles of 401 suspected cases of CL in Sri Lanka were recently explored and some of the cases' immunological responses were investigated, in antibody-detection assays based on the rk39 antigen. These studies were followed by cross-sectional surveys, involving active case detection, in three areas of Sri Lanka, two of them known to be at relatively high risk for CL, with the aims of estimating the local prevalences of the disease and identifying the main risk factors for its acquisition. This appears to be the first detailed report on the prevalence, risk factors and human serological response associated with human leishmaniasis in Sri Lanka. Although the data collected indicated that the transmission of the parasite causing CL was mostly outdoor (and possibly zoonotic) in the north of the country, most of the transmission in the south seemed to be peridomestic. The CL was found to affect a wide age range, in both male and female subjects. Curiously, the 24 cases of CL that were investigated in the rk39 assays gave negative results whereas the single cases of mucosal or visceral leishmaniasis that were studied were found positive for antibodies reacting with the rk39 antigen. More programmes of active case detection need to be launched across Sri Lanka before the true national burden posed by human leishmaniasis can be accurately evaluated. General awareness of leishmaniasis needs to be raised. Hopefully, continued research and disease monitoring will allow the effective control of leishmaniasis in Sri Lanka.

Cross-Sectional Study to Assess Risk Factors for Leishmaniasis in an Endemic Region in Sri Lanka

“…Although it had been reported that outdoor occupation is a risk factor for CL in the northern area of Sri Lanka, 24 our findings do not show such an association. The previous study reported an odds ratio of 6.5 to have CL among armed forces personnel who have significant exposure to forest areas compared with unemployed adults.…”

“…This finding is consistent with observations made in other highly endemic districts in Sri Lanka. 24 Living at the edge of paddy fields was the only identified risk factor for development of leishmaniasis in this study.…”

“…One study conducted in the Anuradhapura, Hambantota, and Moneragala Districts of Sri Lanka, which used active and passive case detection, estimated the prevalence of CL to range from 2.4% to 3.4%. 24 The same study reported that in the northern region of the country, young 21-40-year-old men who spent greater than five hours/ day outdoors were at higher risk for acquiring CL. In the southern region of Sri Lanka, transmission was considered as mainly peridomestic.…”

“…The high CL prevalence among armed forces personnel, males, younger age groups, and those engaged in the outdoor occupations may be caused by sampling of the population screened in the previous study. 24 All of these factors seem interrelated. The population we screened in the Thalawa area was composed mainly of farmers, housewives, and children; there were only five armed forces personnel.…”

“…24 A high percentage (42%) of patients had sought ayurvedic treatment. There was poor social awareness of the disease and of the availability of treatment in this sampled population.…”