Browsing by Author "Wickramasinghe, K."

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Entomological and epidemiological investigations in a newly established focus of cutaneous leishmaniasis in Kegalle district, Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Wickramasinghe, K.; Wijerathna, T.; Gunathilaka, N.; Perera, A.; Bandara, S.
Leishmaniasis is a protozoan infection transmitted by phlebotomine sand flies. The published information on the vector distribution, abundance and potential risk factors that are favorable for disease transmission in Kegalle district are not available. Hence, understanding the trends in disease establishment, epidemiological characteristics, and the bioclimatic suitability of the area for disease prediction. The total number of leishmaniasis patients notified in Kegalle district and Sri Lanka from 2016-2020 was obtained from the Epidemiology Unit, Sri Lanka. Rambukkana and Warakapola Medical Officer of Health (MOH) areas that have reported the highest numbers of cases from 2016 – 2018 in Kegalle district were selected as the study sites in the current study. Patients were visited and socio-economic, demographic, environmental and awareness-related information was collected using an interviewer-administered questionnaire. A randomly selected household with no records of CL in the same locality of the patient household was included as the control group to match the case group at a 1:1 ratio. Entomological surveys were conducted from July 2019- July 2020 using standard entomological techniques. Bioclimatic suitability was evaluated using ecological niche modeling (ENM). A total of 107 patients were reported from Rabukkana and Warakapola MOH areas from 2016-2020. Of them 88 were traced and included in the study. The risk factors were assessed using the chi squared test at 95% confidence intervals. Age was divided into ten-year age groups for analysis. The findings indicate that leishmaniasis in the Kegalle district progressed to the outbreak level within 3 years since the first recorded case in 2016. School students (n=22, 25%, P<0.05) and individuals between 11-20 years of age (n = 33, 37.5%, P<0.05) were identified as the main risk groups. The presence of composting sites (n=65, 73.9%, P<0.05) that provide potential breeding grounds for sand flies, abandoned lands (n=63, 71.6%, P<0.05) which are potential diurnal resting sites of adult sand flies, and suboptimal (dark or normal) lighting conditions (n=87, 98.8%, P<0.05) in the house that may facilitate vector activity were denoted as significant risk factors for leishmaniasis occurrence compared the control group. The level of awareness of the disease was poor in both the test and control groups. Ecological niche modeling revealed that the areas closer to the Kurunegala district, a predominant leishmaniasis endemic district in the intermediate zone, have high bioclimatic suitability for leishmaniasis. The sand flies including, P. argentipes (n=121, 42%) and S. zeylanica (n=164, 56.9%) were present in high densities in this area. Hence, the control efforts focused on raising awareness, while implementing vector control and effective case management, prioritizing the high-risk areas is vital.
The epidemiological trend of cutaneous leishmaniasis in Kegalle district, Sri Lanka: A newly established disease focus and assessment of bioclimatic suitability for disease establishment using ecological niche modelling
(Elsevier, 2023) Wijerathna, T.; Wickramasinghe, K.; Gunathilaka, N.; Perera, A.; Bandara, S.
Cutaneous leishmaniasis is prevalent in Sri Lanka since 1992. It remains as a health issue with increasing numbers and spreading from endemic to non-endemic areas in the county. Kegalle district is a new disease focus, which notified the first case in 2016. However, there is no documented evidence of the vector distribution, abundance and potential risk factors in this district. Two Medical Officer of Health (MOH) areas (Rambukkana and Warakapola) that had reported the highest numbers of cases in the Kagalle district was selected and recorded cases (2016-2020) were obtained. The patients were visited and socio-economic, demographic, environmental and awareness-related information was collected using an interviewer-administered questionnaire. Entomological surveys were conducted from July 2019- July 2020 using three standard entomological techniques. Bioclimatic suitability for the disease transmission was evaluated using ecological niche modelling. A total of 107 patients were reported from both MOH areas and 88 were recruited for the study. The study showed that leishmaniasis in the Kegalle district progressed to an outbreak level within 3 years after reporting the first case. School students (n = 22, 25%, P < 0.05) and individuals between 11 and 20 years of age (n = 33, 37.5%, P<0.05) were identified as the main risk groups, while the presence of composting sites (n = 65, 73.9%, P < 0.05), abandoned lands (n = 63, 71.6%, P < 0.05) in the surrounding and suboptimal (dark or normal) lighting conditions (n = 87, 98.8%, P < 0.05) in the house were identified as main risk factors. Areas closer to the adjacent district (Kurunegala), which is a known endemic district for leishmaniasis indicated a high probability (0.3-0.5) for disease transmission. Sergentomyia zeylanica (n = 164, 56.94%), was identified as the predominant sand fly species followed by Phlebotomus argentipes (n = 121, 42.01%), Sergentomyia babu insularis (n = 2, 0.69%) and Sergentomyia punjabensis (n = 1, 0.35%). Phlebotomus argentipes was captured mostly for outdoor resting sites and S. zeylanica was recoded from both indoor and outdoor. The presence of vectors that can transmit leishmaniasis in these areas along with the potential risk factors could increase the transmission risk and disease establishment in new areas that are ecologically favourable for disease transmission. Therefore, vector control entities should undertake immediate measures to stop spreading the disease into new areas.