Browsing by Author "Ranathunge, R. M. T. B."

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Distribution of leishmaniasis cases and some demographic characters of patients recorded in the Medirigiriya medical officer of health (MOH) area, Polonnaruwa district of Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Karunarathna, D. M. N. P.; Udayanga, N. W. B. A. L.; Ranathunge, R. M. T. B.; Kumarawansha, W. K. W. S.; Ganehiarachchi, G. A. S. M.
Leishmaniasis has been recognized as one of the major challenges to the health sector of many countries. In the Sri Lankan context also, leishmaniasis infections are increasing within the past few years. Evaluation of the spatio-temporal trends in leishmaniasis incidence strongly facilitates the management of leishmaniasis. Therefore, the current study was conducted to identify recent spatial and temporal trends in leishmaniasis distribution, while assessing the characteristics of susceptible population to leishmaniasis infection in the Medirigiriya Medical Officers of Health (MOH) area in the District of Polonnaruwa, which reported the highest number of Leishmaniasis cases over the period from 2015 to 2022. Monthly records of reported leishmaniasis cases in Medirigiriya MOH area were obtained at monthly intervals from Epidemiology Unit, Sri Lanka from January, 2018 to June, 2022. Spatial maps of the recorded leishmaniasis case distribution in each Public Health Inspector (PHI) area were developed using ArcGIS (version 10.8). The paired-Chi square was used to investigate the impact of gender and age on the infection. The Medirigiriya MOH area had reported a total of 418 cases within the study period. Among the five PHI areas, Medirigiriya (34.7%) and Diulankadawala (33.8%) PHI areas reported the highest incidence of leishmaniasis cases, emerging as the high-risk areas. Meanwhile, Ambagaswewa PHI area denoted the lowest susceptibility (7.6%). As suggested by the results of the paired-Chi square test, emergence of leishmaniasis was characterized with significant spatial and temporal trends (P<0.05). The Percentage Infected Male: Female Ratio (PIMFR) suggested that the, males had a relatively high susceptibility for leishmaniasis infection than females, with an average PIMFER of 62.4:37.6. Significant shifts in the age of leishmaniasis patients were identified throughout the study period (P<0.05). Population belonging to the age group of 40 to 60 years (44%) and 21 to 40 years (25.2%) were identified as the most vulnerable age group for the incidence of leishmaniasis. On the contrary, age groups of > 60 years reported the lowest vulnerability (9.2%) for leishmaniasis infection. The identification of the potential high risk PHI areas with high susceptibility to leishmaniasis, along with the vulnerable age groups in the community would assist the relevant vector controlling agencies to concentrate their efforts, ensuring the effective controlling of leishmaniasis outbreak occurrence within the Medirigiriya MOH.
First report of Culex (Lophoceraomyia) cinctellus in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Rangana, U. L. P.; Kumarasinghe, K. G. D. S. G. S.; Jayasinghe, H. P. N. T.; Refai, F. W.; Udayanga, N. W. B. A. L.; Ranathunge, R. M. T. B.
Disease epidemics caused by mosquito vectors have been a significant challenge faced by the health sector of Sri Lanka. Routine entomological surveillance is practised as a key approach in monitoring the population dynamics of mosquito vectors, which is vital for epidemic management. A recent preliminary surveillance conducted in Banduragoda Public Health Inspector (PHI) in Mirigama Medical Officer of Health (MOH) area has reported the presence of Culex (Lophoceraomyia) cinctellus, for the first time in Sri Lanka. Therefore, the current study was conducted to validate the presence of Cx. cinctellus, based on morphological and molecular evidence. Larval and adult surveillances were conducted from October 2019 to April 2020 at fortnight intervals in the Banduragoda Public Health Inspector (PHI) area. Standard siphoning methods were used in larval surveillance, while Cattle Baited Traps (CBT), Gravid Traps (GT), Light Traps (LT), Bird-Baited Traps (BBT), Dog Baited Traps (DBT) and diurnal human landing collections were used for adult surveillance. The collected specimens were transported to the Entomology Laboratory of the Medical Research Institute (MRI). The immature larvae were reared up to fourth instar stage. Adults and reared larvae were identified to the species level using standard morphological keys. Further, DNA extracted from the head, and thoracic regions of the reared mosquitoes were sequenced. Subsequently, the sequences were analysed for sequence identity using NCBI BLAST analysis and Geneious Trial (version 7.1.3). Adults of Cx. cinctellus were reported from BBT and in human baited collections. Morphological features such as well-developed pulvilli, wing with vein 1A ending before the apex of cross vein mcu, basal transverse pale bands in abdominal terga and two labial basal setae in proboscis were identified as unique features of Cx. cinctellus. Females of Cx. cinctellus reported a mean thoracic length of 0.58 ± 0.02 mm, thoracic width of 0.63±0.02 mm. The average abdominal length and width were 2.15±0.03 mm and 0.61±0.01 mm respectively, along with a wing length of 2.91±0.02 mm. The results of the molecular analysis further confirmed the morphological identification. This finding warrants the importance of strengthening routine entomological surveillance activities further to study the dispersal and population dynamics of Cx. cinctellus in Sri Lanka.
Study on effect of quality of water in Anopheles mosquito breeding habitats and control of Anopheles mosquitoes using larvivorous fish and carnivorous copepods
(University of Kelaniya, 2017) Ranathunge, R. M. T. B.
Malaria is one of the most important health problems worldwide transmitted by anopheline (Diptera: Culicidae) mosquitoes. Sri Lanka declared elimination of malaria depending on the absence of indigenous cases of malaria for the past three years There is a possible risk of spreading malaria from imported cases as the major and potential vectors of malaria are still present in many parts of the country. Therefore, understanding the effect of abiotic and biotic factors on biology and ecology of immature stages of malaria vectors and identifying effective larval control methods will be very important for controlling malaria vector mosquitoes. Therefore, this study was focused on monitoring of entomological and ecological factors affecting distribution and density of malaria vector mosquitoes in the Districts of Mannar and Trincomalee (PART 1) and identifying possible biological control agents for malaria vector mosquitoes in the District of Kandy (PART 2). In the PART 1 of the study, a total of 1 440 households in eight possible malaria sensitive (sentinel) sites in the Districts of Mannar and Trincomalee were recruited Monthly entomological surveillance was performed in all study sites for 16 months (April, 2013 to July 2015). Physico-chemical parameters and aquatic macro-invertebrates in anopheline breeding habitats were studied. A total of 19 280 anopheline mosquitoes belong to 13 species were collected from the eight sentinel sites in two districts by standard anopheline collecting techniques. Abundance of anopheline larvae showed significant positive correlation (p < 0.05) with physico-chemical parameters in breeding habitats such as, temperature, Dissolved Oxygen (DO), and turbidity. However pH, conductivity, Total Dissolved Solid (TDS), salinity and hardness did not correlate significantly (p > 0.05) with abundance of anopheline mosquito larvae. Air temperature, rainfall intensity and wind speed are critical meteorological factors for distribution and abundance of malaria vectors A total of 34 and 35 macro-invertebrates taxa were collected from anopheline mosquito breeding habitats in the Districts of Mannar and Trincomalee respectively Presence of anopheline mosquito larvae was not significantly correlated (p > 0.05) with the prevalence of aquatic macro-invertebrate predators of the Orders Decapoda, Coleoptera. Hemiptera or Odonata. In the PART 2 of the study, highest predatory efficacy was observed in two fish species, 0. niloticus and P. reticulate under the both laboratory and field conditions respectively A copepod species, M scrassus denoted the highest predatory efficacy under the both laboratory and field conditions. Knowledge on ecological and biological factors affecting distribution of malaria vector mosquitoes and biological control agents for controlling malaria vector mosquitoes will be important for controlling malaria transmission from imported cases to neighborhoods in the future.
Use of morphological and molecular methods in identification of Asian bush mosquito, Aedes japonicus (Theobald, 1901), in Sri Lanka
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Wickramasinghe, T. K. C.; Udayanga, N. W. B. A. L.; Manamperi, A. A. P. S.; Hapugoda, M. D.; Karunarathna, K. H. T.; Ranathunge, R. M. T. B.
Conducting routine entomological surveillance to identify new vectors and changes in the distribution patterns of vectors is important for the management of mosquito borne diseases in Sri Lanka. A recent preliminary entomological survey reported the presence of Aedes japonicus in Sri Lanka in March 2021. Therefore, the current study was conducted to validate the presence of Ae. japonicus in Sri Lanka, based on morphological and molecular evidence. The search for Ae. japonicus breeding sites and developmental stages using standard siphoning methods were conducted in Kosgama and Pallekanugala areas located in the Districts of Colombo and Kegalle, respectively, from May to December 2021. Collected immature stages were reared up to the fourth instar stage or adult, and specimens were identified to species level using standard morphological keys. Further, DNA was extracted from the head, and thoracic regions of the reared mosquitoes and Polymerase Chain Reaction (PCR) was performed. The amplified products were sequenced at a commercial facility (Macrogen Inc. co. Ltd., Seoul, Korea). Subsequently, the sequences were analysed for sequence identity using NCBI BLAST analysis and Geneious Trial (version 7.1.3). Based on the morphological characteristics, larvae of Ae. japonicus were identified from both study areas. Ae. japonicus was reported only from natural breeding containers such as bamboo plants and tree holes in both study areas. The molecular analysis further confirmed the morphological identification. Further, newly reported Ae. japonicus population denoted a close relationship to the Austrian/Slovenian population. Ae. japonicus is well adapted to temperate climates and has been reported to possess a strong tendency to expand and colonies into new territories, which is facilitated by human-mediated, passive transportation. According to Unweighted Pair Group Method with Arithmetic Mean (UPGMA) based hierarchical cluster analysis, newly discovered Ae. japonicus denoted strong affinity to a previously detected Ae. japonicus strain in Eastern Austria/Slovenia. The dispersal and population dynamics of Ae. japonicus should be thoroughly surveyed in Sri Lanka, as this species is a potential vector of Japanese Encephalitis.