International Postgraduate Research Conference (IPRC)
Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/155
Browse
4 results
Search Results
Item Awareness of Rickettsial Infections (Typhus Fever) in a High Endemic Community in Hambantota District, Sri Lanka(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Ashani, M.L.S.; Chandrasena, T.G.A.N.; Gunathilaka, P.A.G.N.; Premaratna, B.A.H.R.Rickettsial infections are re-emerging in Sri Lanka with an average annual incidence of 1500 patients. Low awareness and the scarcity of proper diagnostic tools has resulted in delayed disease diagnosis and negligence towards the disease leading to extended morbidity in Sri Lanka. Community awareness of the disease is important for timely diagnosis and control. Hambantota district in Southern Province of Sri Lanka, which records the fourth highest incidence of typhus, was selected for the study. Households (n= 204) situated around index cases of typhus fevers were randomly selected for the survey. An interviewer-administered questionnaire was used to gather data on illness awareness (disease aetiology, symptoms, transmission, disease associations) by selecting a consenting representative from each household. Descriptive and inferential analysis of the data was carried out using SPSS IBM statistical software. Of the 204 interviewed, only one (0.5%) identified the illness as “typhus”. Majority identified the disease as “Peacock fever” (43.12%; n= 88) followed by “tick fever” (14.71%; n=30). It is interesting to note that 41.67% (n=85) of the households were not aware of the disease even though they are living in a disease endemic area. None were aware of the etiological agents of typhus fever. Among those with awareness, 65.55% (n=78), believed that infection was tick-borne and the vector ticks were harbored by peacocks. About 27.73% (n=33) believed that the transmission was directly from peacocks, followed by other birds (2.52%; n=3). Majority 82.35 %, (n=98) were unaware of symptomatology while only 1.77%, (n=14) recognized it only as a febrile illness and myalgia (4.20%; n=5). Of those who were aware, 73.95 %, (n=88) had received information through acquaintances, 25.21% (n=30) from health personnel and one through mass media. None were aware of preventive measures. The results of the present study highlight the lack of proper awareness of the disease condition, which may adversely impact on disease control effortsItem Scrub Typhus, Its potential zoonotic hosts and vectors in Sri Lanka: A preliminary report(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Ashani, M.L.S.; Chandrasena, T.G.A.N.; Gunathilaka, P.A.G.N.; Premaratna, B.A.H.R.Scrub typhus or tsutsugamushi disease is an acute febrile infectious disease endemic in the “tsutsugamushi triangle” of Southeast Asia, the Asian Pacific rim, and Northern Australia, with approximately one billion individuals at risk of infection. Currently one million new infections occur annually. The term scrub typhus is descriptive of the typical habitat endemic to the vector, although its existence is not limited to such niches. It is caused by a Gram-negative, obligate intracellular bacterium Orientia tsutsugamushi, of the Rickettsiaceae family, transmitted to humans following an accidental bite by an infected larval trombiculid mite commonly known as chiggers. Chiggers are a group of ectoparasites prevalent on a variety of mammals, mainly small mammals like rodents. Clinical cases of scrub typhus are documented in almost all ecological zones including both rural and urban Sri Lanka, as year-round sporadic cases or as outbreaks. However, the reservoir hosts in Sri Lanka and transmitting vector species are yet to be identified. Such knowledge is important for effective implementation of control measures of this re-emerging infection. Therefore, this study was designed to live capture small rodent/mammal hosts and identify chigger mite species present in the country. Traps designed to live capture small rodents/mammals were placed in peri-domestic areas of clinically confirmed scrub typhus patients in southern province, Sri Lanka. Traps baited with fried coconut were placed around residences and in pre-selected sites with scrubby vegetation and rodent burrows, one hour before sunset and were retrieved the next day morning. The captured animals were anaesthetized with ketamine/xylazine and inspected for the presence of vector mites. Collected mites were preserved in 70% alcohol and identified by microscopy using standard morphological keys. Collected data were analyzed using chi square test, MINITAB 17 statistical software. Rodents belonging to Rattus norvegicus (n=15; 56%), Rattus rattus (n= 10; 37%) and shrews of Suncus murinus (n=2, 7.4%) were captured during the study over 6 months and a total of 147 mites were isolated. Isolated chigger mites belonged to genus Leptotrombidium (n=90; 67%), Eutrombicula (n=31; 23%), Helenicula (n=24,17 %) and species Leptotrombidium lagone (n=2; 1.5 %). Majority were potential vectors for Orientia tsutsugamushi. It is noted that Rattus norvegicus harbored significantly more chigger mites (mean of 7 per individual; χ2 = 110.35; p <0.001] compared to other species captured. We are currently in the process of molecular speciation of sampled chigger mites and molecular detection of Orientia tsutsugamushi in collected mites in order to determine their vectorial potential.Item Potential Use of a Combined Sterile Insect Technique (SIT) and Wolbachia-Based Approach for the Control of the Dengue Vector Aedes albopictus in Sri Lanka(19th Conference on Postgraduate Research, International Postgraduate Research Conference 2018, Faculty of Graduate Studies,University of Kelaniya, Sri Lanka, 2018) Wijegunawardana, N.D.A.D.; Chandrasena, T.G.A.N.; Abeyewickreme, W.; Dassanayake, R.S.; Xi, Z.; Bourtzis, K.; Gunawardene, Y. I. N.S.This study addresses the possibility of using a novel and environmental friendly strategy of combined sterile insect technique (SIT) and a Wolbachia-based approach in Aedes albopictus population control efforts in Sri Lanka. The above strategy combines irradiation and the intracellular endosymbiont bacteria Wolbachia, in insects which are vertically transmitted from mother to offspring. Releasing sterile male mosquitoes in the wild will introduce sterility for suppression of Ae. albopictus wild mosquito population. The strategy aims at the releasing of sexually incompatible Wolbachia triple infected and irradiated male mosquitoes on a large scale to the natural environment. By integrating irradiation, any accidentally released female mosquito will be made fully sterile, and hence the risk of population replacement of the target population with triple infected mosquitoes is eliminated. Therefore, the combined SIT/IIT approach offers a safe and bio-secure strategy for the population suppression of Ae. albopictus in Sri Lanka. The overall work involved assessment of the density and species abundance of wild mosquito populations, introgression, and characterization of Wolbachia triple infected Ae. albopictus line in a Sri Lankan genetic background and determination of minimum sterility dose for the males and females of the introgressed line. Results revealed that Ae. albopictus mosquito was the dominant vector species in the study area (Narangodapaluwa PHI area) with an average ovitrap index of 75.25% (range; 56.9% - 94.7%) over the study year. The frequency of Wolbachia infection among the mosquito population was ~17% (13/78). The most prominent Wolbachia super group infecting the wild mosquito species was the B group and Ae. albopictus was naturally infected with both strains A and B. Eighty-five new alleles and 8 complete allelic profiles were submitted to the Wolbachia MLST database. All sequencing data were deposited in the Genebank under the accession numbers MH447376-MH470292 and MH756095-MH777430. Successful transfer of Wolbachia triple infection to Ae. albopictus into Sri Lankan genetic background was achieved through an introgression experiment and characterization of the newly developed Ae. albopictus line expressed partial CI and revealed competitive fitness cost for fecundity, fertility, and longevity compared with wild-type while there was no cost for pupation rate, adult emergence and sex ratio. Therefore, integration of an irradiation (dose; 30Gy) is recommended to achieve complete male and female sterility prior to mosquito release (minimum sterility dose for males - 28 Gy and females - 30 Gy). This minimum sterility dose is lower than the irradiation dose applied for SIT and had not resulted in a significant effect on male competitiveness. Therefore, a combined SIT and Wolbachia based approach in Ae. albopictus dengue vector control is recommended as an additional tool in integrated vector management in Sri Lanka.Item Determination of appropriate positioning of the ovitraps for dengue mosquito surveillance(Faculty of Graduate Studies, University of Kelaniya, 2015) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Chandrasena, T.G.A.N.; Dassanayake, R.S.; Gunathilaka, P.A.D.H.N.; Abeyewickreme, W.Three months ovitrap survey was conducted to assess the suitable position in placing the ovitraps for dengue vector mosquito surveillance and this study was initiated due to loss of valuable data from our previous studies as a result of physical damage of the ground kept ovitarps. Thirty four households in the Ragama Medical Officer of Health area in Gampaha District were selected to conduct the ovitrap survey during the period of May to July, 2015 to select the most appropriate positioning of the ovitrap. The conventional black plastic ovitraps (3.2x 2.7 cm) were used in this purpose to collect aquatic stages of Aedes mosquitoes while placing plywood paddle (4 x 0.5 cm) over the upper rim of each coded ovitrap. A total of 136 ovitraps were used in the study site providing four ovitraps (2 each indoor & outdoor) for each house while one of the ovitraps of indoor and outdoor being hung and other being kept on the ground. In positioning ovitraps, the outdoor ones were kept 3m away from the house while leaving indoor ovitraps in the living room in close proximity to racks/hanging clothes or partially shaded places. Following collection of samples at each week, ovitraps were washed thoroughly, refilled with new water and a new paddle, and corresponding data were recorded and analyzed. These analyses revealed that number of larvae and the number of Aedes mosquito eggs present in the two different ovitrap positions (Ground kept vs Hung) were not significantly different; in spite of significant difference (P=0.001) between the outside and inside placements. Further, significantly higher values were observed for both number of mosquito eggs and larvae present in each ovitrap kept outside (60 and 13 respectively) than those placed inside (32 and 3 respectively). Furthermore, slightly higher values were observed for hung ovitraps (49 and 9 respectively) than ones kept on the ground (43 and 7 respectively). Finally, ovitrap placed above the ground level was selected in continuing the routine ovitrap survey, as there was considerable reduction of mechanical damage to the latter thus facilitating continuous data collection.