Browsing by Author "Kusumawathie, P.H.D."

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Anopheline breeding in river bed pools below major dams in Sri Lanka
(Elsevier, 2006) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.D.; Wijeyaratne, M.J.S.; Yapabandara, A. M. G. M.
Anopheline mosquito larval surveys were carried out from September 2000 to August 2002 in Mahaweli and Kelani river beds, below five major dams in the wet and intermediate zones of Sri Lanka, to study the prevalence of anopheline species in these areas. In each study site, all permanent and semi-permanent pools were surveyed fortnightly by dipping at 6 dips/m(2) surface area of water. Larvae were collected in separate containers, staged and identified at their third and fourth stages. During each survey, the surface area and depth of pools were recorded and each reading was considered as an individual observation. River bed pools below the dams contained stagnant clean water with a little or no aquatic vegetation. The majority of pools were < or =1m(2) in surface area and < or =75 cm in depth. Anopheline mosquito breeding was seen throughout the year in each study site. The average percentage of pools positive for anopheline larvae, the number of larvae per 100 pools and 100 dips were 14.85%, 32.34 and 9.29, respectively. Thirteen anopheline species, including 10 potential vectors, namely, An. barbirostris, An. culicifacies, An. jamesii, An. maculatus, An. nigerrimus, An. peditaeniatus, An. subpictus, An. tessellatus, An. vagus and An. varuna were found breeding in the river bed pools.
Biocontrol potential of six locally available fish species as predators of Aedes aegypti in Sri Lanka
(Elsevier Ltd, 2021) Ranathunge, T.; Kusumawathie, P.H.D.; Abeyewickreme, W.; Udayanga, L.; Fernando, T.; Hapugoda, M.
ABSTRACT: This study was conducted to evaluate the potential of six locally abundant fish species to control Aedes mosquito larvae and thereby manage dengue epidemics in a sustainable, cost-effective and environmentally friendly manner. The biocontrol efficacy of six larvivorous fish species, namely, Poecilia reticulata, Rasbora daniconius, Aplocheilus dayi, Oriochromis mossambicus, O. niloticus and Puntius bimaculatus, was evaluated under laboratory and field conditions. Five size-matched fish (of the same species) were introduced into separate tanks (replicates) containing 2 L of dechlorinated water and 200 third instar larvae of Aedes aegypti (L.). The number of larvae consumed by each fish species was recorded at three-hour intervals for 24 h. Acclimatized fish were introduced into a total of eighteen artificial breeding habitats located in the Gampola Medical Officer of Health (MOH) area at the species level with three replications. In addition, three breeding sites without fish were monitored as controls. Aedes larvae were monitored by dipping and siphoning methods in each breeding habitat at weekly intervals for three months and the number of fish surviving in each habitat was tallied. Over 24 h under laboratory conditions, O. mossambicus showed the highest predation rate, consuming 320.2 ± 14.5 larvae per day, with a predatory efficiency of 87.5 ± 3.5%. In comparison, O. niloticus consumed 264.6 ± 12.2 larvae per day with consumption efficiciency of 78.1 ± 3.7%, whereas R. daniconius had the lowest larval consumption (33.2 ± 2.7 larvae per day) and predatory efficiency (33.2 ± 3.2%). Over 12 weeks of observation under field conditions, breeding sites with Ap. dayi had the lowest Aedes larval counts, followed by Po. reticulata. Considering predation efficiency and survival under field conditions, Ap. dayi and Po. reticulata were considered to be the best potential candidates for biological control of Ae. aegypti. Further studies under field settings are warranted to evaluate the survival and predatory potential of the selected candidates under more varied environmental conditions.
Cost analysis of application of Poecilia reticulata (guppy) and temephos in anopheline mosquito control in river bed pools below the major dams in Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2004) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.D.; Wijeyaratne, M.J.S.
Costs and effectiveness of application of Poecilia reticulata (guppy) and temephos in anopheline mosquito control in river basins below the major dams of Sri Lanka
(Royal Society of Tropical Medicine and Hygiene, 2008) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.D.; Wijeyaratne, M.J.S.
In this study we examined the costs and effectiveness of using larvivorous fish, Poecilia reticulata, and a chemical larvicide, temephos, in anopheline mosquito control in the riverbeds below the major dams in Sri Lanka. Five riverbeds below the dams, namely Laxapana, Kotmale 1, Kotmale 2, Nilambe, Rantembe and Victoria, were selected. Riverbed pools in Laxapana and Kotmale 1 were treated with P. reticulata; Rantembe and Victoria were treated with temephos; and Kotmale 2 and Nilambe were kept as controls. In each area, the anopheline larval density, before and after application of fish/temephos, was estimated. The cost of application of fish/temephos was estimated by activities involved for each treatment. After intervention, there was a significant reduction in anopheline larval density in the fish-treated areas compared with the temephos-treated and control areas. Application of P. reticulata was 2.67 times less costly than that of temephos. The cost of fish application can be further reduced if the community is involved in the application
Demographical characterization of dengue infected patients in Akurana medial officer of health area
(central Province of Sri Lanka, University of Sri Jayawardnapura, Sri Lanka., 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Najim, M.M.M.; Amarasingha, U.S.; Abeyewickreme, W.
Dengue has been recognized to be one of the major threats on the public health of many tropical countries including Sri Lanka. Controlling of the high rate of mortality caused by dengue, which remains without being altered regardless of the immense efforts and control strategies of the relevant authorities, has remained as a major challenge for the Sri Lankan health sector. Vulnerability assessment of communities to dengue infection is of higher importance in drafting and implementation of management plans to ensure effective management and controlling of dengue epidemics at the regional scale. Therefore, a statistic based analysis of the dengue patient characteristics was carried out to determine the susceptibility of population to dengue infection in Akurana Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2010 to 2014 of the Akurana MOH division were collected. Normal Chi square test coupled with Paired-Chi square test was devised to investigate the impact of sex and age on the infection. MINITAB (version 14.12.0) software package was used for statistical analysis. In accordance with the results of the normal Chi square test, the Percentage Infected Male: Female Ratio (PIMFR) remains significantly altered throughout the period of study (p=0.001 61 (1.84%). However, according to the Paired-Chi square test, the vulnerability of age groups tend to shift significantly throughout the study period [>Χ2 (7, 0.95) = 14.067]. In conclusion males tend to indicate relatively high susceptibility to dengue. Age groups of 6 - 10, 11 - 20 and 21 - 30 could be recognized as highly vulnerable age groups in the community for dengue, while age group of >61 emerge as the least vulnerable age group for the infection of dengue in the Akurana MOH.
Disease transmitting mosquito species breeding in water storage tanks in Kandy, Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2005) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Wickremasinghe, D.R.; Jayasooriya, G.A.J.S.K.
Emerging Spatio-Temporal Trends in Dengue Incidence in Poojapitiya Medical Officer of Health (MOH), Central province, Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Abeyewickreme, W.
Dengue has emerged as one of the major threats to the health sector of many countries including Sri Lanka, due to the increasing number of reported dengue cases over time. Therefore, a statistical and geo-informatics based analysis of the spatio-temporal trends in dengue distribution was carried out to identify recent spatial and temporal trends in dengue distribution patterns, while assessing the susceptibility of the population to dengue infection in the Poojapitiya Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2009 to 2013 of the Poojapitiya MOH area were acquired and spatial maps of the recorded dengue case distribution in each Grama Niladhari Division (GND) were developed by using Arc GIS (version 10.2). Normal Chi square test coupled with Paired-Chi square test in MINITAB (version 14.12.0) were used to investigate the impact of gender and age on the infection. Galhinna GND indicated the highest susceptibility to dengue throughout the study period, while the rest of the GNDs indicate less (37 GNDs) or null (29 GNDs) susceptibilities. As suggested by the results of the Paired-Chi square test [>Χ 2 (66, 0.95) = 85.951], the emergence of dengue outbreaks indicated a significantly declining trend in recorded dengue cases in all of the GNDs (regardless of the outbreak in 2012) during recent years. The Percentage Infected Male : Female Ratio (PIMFR) suggested that the, males had a relatively high susceptibility for dengue infection than females with 63.9 : 36.1 of average PIMFER (p=0.00<0.05 at 95% of significance). According to the Paired-Chi square test, the vulnerability of the age groups shifts significantly throughout the study period [>Χ 2 (7, 0.95) = 14.067], where the age groups of 11 - 20 and 21 – 30 indicated high vulnerability to dengue, while >61 age group remained as the least vulnerable group for dengue infection. The identification of the potential high risk GNDs with high susceptibility to the infection of dengue 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 dengue outbreak occurrence within the of Poojapitiya MOH.
Emerging spatio-temporal trends of dengue incidence in Colombo and Kandy Districts, Sri Lanka
(Moleclar Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Abeyewickreme, W.
BACKGROUND: Dengue has become a prominent challenge to the health sector in Sri Lanka. Prior identification/prediction of possible risk areas with high susceptibility to dengue, could be of major importance in ensuring the effective regulation of dengue epidemics. Therefore, the current study attempts to investigate the spatio-temporal trends in dengue incidence and priority risk factors that characterize dengue epidemics, aiming to stratify the Colombo and Kandy Districts into high, moderate and low risk areas via development of dengue risk maps by devising a statistical and geo-informatics based approach. METHODOLOGY: Socio-economic data of dengue patients and healthy volunteers in selected high risk MOH areas of Colombo (5) and Kandy (5) Districts were obtained through an interviewer administrated questionnaire. Previously reported dengue cases from 2009 to 2014 in each MOH were acquired. The spatio-temporal trends in dengue incidence of studied MOHs, were investigated at the Grama Niladhari Division (GND) level by using Arc GIS (version 10.2). The impacts of gender and age of the community on the disease prevalence were investigated by using normal Chi square test and Paired-Chi square test in SPSS (version 23). RESULTS: At present, 95% and 81% of the overall socio-economic surveillance has been completed in Kandy and Colombo Districts, respectively. Spatial maps on disease outbreaks have been developed for Akurana, Doluwa, Gampola, Gangawatakorale, Kandy Municipal Council (KMC), Kundasale and Poojapitiya MOH areas. According to results of the Paired-Chi square test, the emergence of dengue outbreaks indicated a significantly declining trend in recorded dengue cases in most of the GNDs within the studied MOHs, during the recent years. The Percentage Infected Male:Female Ratio (PIMFR) remained significantly altered throughout the period of study (p=0.001<0.05 at 95% of significance). Within the studied MOHs, males tend to indicate relatively high susceptibility for dengue infection than females (with 58.6: 41.5 of average PIMFR). The age group of 11 – 20 and 21 – 30 years were identified as with highest vulnerability to dengue, while the age > 61 years indicated the least vulnerability in all the MOHs. According to the Paired-Chi square test, the vulnerability of age groups was found to shift significantly throughout the study period [>Χ2 (7, 0.95) = 14.067]. CONCLUSIONS: The KMC and Gampola MOHs indicate relatively high susceptibility to dengue within the district of Kandy. Within all the studied MOHs, males tend to indicate relatively high susceptibility to dengue. Age groups of 11 - 20 and 21 – 30 denote relatively higher vulnerability to dengue, while age group of > 61 emerge as the least vulnerable group for the infection of dengue in the studied MOHs.
Evaluation of the spatial and temporal trends of dengue outbreaks in Akurana, Central Province, Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2015) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Najim, M.M.M.; Amerasinghe, U.S.; Abeyewickreme, W.
Renowned as the world's fastest growing vector borne disease, dengue has become one of the major health issues in Sri Lanka leading to an alarming concern due to recent outbreaks throughout the country. Despite the immense efforts taken by the relevant authorities to reduce the rate of mortality, the average number of dengue cases recorded in each year remains around 30,000-35,000 without being changed significantly over time in Sri Lanka. Investigation of the trends in spatial and temporal distribution patterns of dengue is often treasured in the drafting and implementation of management/action plans to ensure effective management of dengue epidemics at regional scale. Thus, a statistical and geo informatics based analysis of the recent trends in dengue distribution was carried out to identify spatial and temporal trends in distribution patterns of Dengue in the Akurana Medical Officer of Health (MOH) area. Monthly records of reported dengue cases from 2010 to 2014 of the Akurana MOH area were obtained and were subjected to a scatter plot analysis in MINITAB (version 14.12.0) to identify the temporal patterns in the recorded dengue cases. Spatial maps of the recorded dengue case distribution in each GND for each month and for the whole study period were prepared by using Arc GIS 10.1. The spatial and temporal variations of dengue outbreak distribution within the Akurana MOH (at GND level) were analyzed to identify the recent trends in dengue incidence. Akurana, Bulugahathenna, Dippitiya, Dunuwila, Konakalagala and Neeralla localities could be identified as areas with relatively high risk to dengue outbreaks throughout the study period, while localities such as Balakanduwa, Delgasgoda, Delgasthenna, Malgamandeniya, Marahela, Palleweliketiya and Udawelikatiya emerged as areas with low risk. As suggested by the results of the paired-Chi square test [>Χ2 (30, 0.95) = 43.773], the emergence of dengue outbreaks indicated a significantly declining trend of recorded dengue cases in most of the GNDs (Aswadduma, Delgasgoda, Kurugoda, Malgamandeniya, Palleweliketiya and Walahena etc.) during the recent years. The evaluation of the trends in temporal and spatial distribution of dengue outbreaks at the localized level, could be recommended as a useful tool in the planning and implementation of action plans to control the rise of dengue, while evaluating the efficacy of already implemented control measures at regional scale.
Factors affecting transmission of chikungunya using Geographical Information System (GIS)
(Sri Lanka Association for the Advancement of Science, 2009) Hapugoda, M.D.; Gunawardena, N.K.; Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Abeyewickreme, W.
Transmission of chikungunya has been observed in many parts of Sri Lanka during the past few years. The objective of this study was to identify possible factors affecting transmission of chikungunya in a high risk area and to intervene and monitor those using GIS. Entomological, environmental, socio-economic and other possible factors were examined with regard to a chikungunya hot-spot in Kandy municipality for 12 months starting from April 2008. Hundred house-holds from 33 clusters were recruited. The distant between each cluster was maintained at a minimum of 200 m. Micro level approaches for collection of position, population, environmental, socio-economic and other related information were performed at each house-hold through a pre-tested questionnaire. Monthly entomological and epidemiological surveillance were conducted for 12 months. Digital topographical maps and meteorological information were obtained. GIS was used to map the selected households and to highlight the spatial and temporal distribution of factors under study. Selected risk area was an urban area where homesteads were the major land use pattern. The weather pattern of the study area was typical that of the Wet Zone. Entomological surveillance conducted showed the presence of high density of Aedes albopictus mosquitoes in more than 90% of the key (artificial) breeding habitats. Socio-economic data revealed although all house-holds have a sound knowledge on transmission on dengue including preventive measures, they were less concerned about the key mosquito breeding sites. GIS maps generated during the study showed distribution of these identified factors in all clusters. House index and man hour density of Ae. albopictus showed a positive correlation with rainfall, with a lag period of 2 and 3 months. The generalized high density of Ae. Albopictus suggest that this species may play a major role in transmitting chikungunya in the study area. In conclusion, the presence of high density of Ae. albopictus and lack of concern about key mosquito breeding sites in all clusters may be important risk factors. GIS-based maps can be used as an important tool to find out spatial and temporal distribution of possible risk factors in a selected hotspot, which would enable health authorities to prioritize implementation of control activities in a cost effective manner
Geographical Information System (GIS)-based maps for monitoring of entomological risk factors affecting transmission of Chikungunya in Sri Lanka
(Faculty of Tropical Medicine, Mahidol University, 2008) Hapugoda, M.D.; Gunawardena, N.K.; Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Hapuarachchi, H.A.C.; Abeyewickreme, W.
INTRODUCTION: Chikungunya is an important mosquito-born viral infection in Sri Lanka at present. OBJECTIVE: To prepare OUS-based maps Tor monitoring of entomological risk Factors affecting transmission of chikungunya. RESEARCH DESIGN: Entomological risk factors affecting transmission of chikungunya were examined in a chikungunya hot-spot in the District of Kandy, Sri Lanka from April to July in 2008. Hundred house-holds in 33 clusters were recruited. The distant between clusters was at least 200m which is beyond the maximum flight range of Aedes mosquitoes, the vectors of chikungunya. Monthly surveillance was conducted using standard entomological surveillance methods followed by obtaining information through a pre-tested questionnaire. G1S was used to map the selected house¬holds and display entomological data. RESULTS: GIS-based maps were developed to highlight the spatial and temporal distribution of vectors, their density and the presence of key breeding sites. Maps showed the presence of high density of Aedes albopictus mosquitoes in more than 90% of the key (artificial) breeding habitats in all clusters throughout the study period. DISCUSSION: Generalized high density of Ae. albopictus suggests that this species may play a major role in transmitting chikungunya in the study area. GIS-based 'maps may be used as an important tool to find out spatial and temporal distribution of vectors, their density and key breading sites in a selected hotspot, which would enable cost effective and efficient interventions for vector control in disease endemic areas.
Importance of private health sector in malaria surveillance: a case study in Nuwara-Eliya district, Sri Lanka
(Sri Lanka College of Microbiologists, 2002) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.
OBJECTIVE: To determine the Utilization of public and private health facilities by suspected malaria cases in Divisional Director of Health Services (DDHS) area Hanguranketha in Nuwara-eliya district (from July 2000 to June 2001). DESIGN, SETTING AND METHODS: Two state hospitals, DH Rikillagaskada and RH Gonagantenna were selected as public health facilities. Seven clinics at Rikillagaskada and Gonagantenna in which government medical officers engaged in private practice after duty hours were selected as private health facilities. The number of cases blood filmed for malaria at public facilities was obtained from hospital records. Data for the private sector was obtained using a pre designed form. Reporting from the private sector was done on a monthly basis. RESULTS: Among 572 cases blood filmed at government hospitals, 22 were positive for P.vfvax. In the private sector. 634 cases of suspected malaria were reported and treated on clinical grounds. During the study period, 40 P.vivax and 65 P.falciparum cases were detected by examining 1270 blood films collected by Active Case Detection and Special Malaria Clinics, conducted in the villages with risk of malaria transmission within the study area. Of the microscopically confirmed malaria cases, 15.4% of P.falciparum infections were resistant to chloroquine. Investigation of malaria cases revealed 66.7% of cases were indigenous while 33.3% were imported. If the Slide Positive Rate (SPR) of the government facilities is applied to the data of the private sector, 610 cases would have been given chloroquine without actually having malaria. CONCLUSIONS: According to this study, 52.57% of suspected malaria cases had sought treatment at private health facilities. Incorporating the private health sector in malaria surveillance would be helpful in correct treatment and control of malaria in malarious areas. Unnecessary anti malarial therapy should be reduced by provision of laboratory facilities at private health centers. ACKNOWLEDGEMENTS: Assistance provided by the Provincial Director Health Services, Central Province and Deputy Provincial Director Health Services, Kandy, and the Director Anti-Malaria Campaign is acknowledged.
Knowledge, Attitude and Practices (KAPs) based risk factors for dengue in the Gampola Medical Officer Health area, Kandy District, Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2016) Udayanga, N.W.B.A.L.; Gunathilaka, P.A.D.H.N.; Iqbal, M.C.M.; Kusumawathie, P.H.D.; Najim, M.M.M.; Amarasinghe, U.S.; Abeyewickreme, W.
Laboratory studies on larvivorous potential of five fish species against Aedes ageypti (Linnaeus) and Ae. albopictus (Skuse)
(Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Sri Lanka, 2015) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Gunathilaka, P.A.D.H.N.; Hapugoda, M.; Abeyewickreme, W.
BACKGROUND: The dengue vectors, namely, Aedes aegypti (Linnaeus) and Ae. albopictus (Skuse) are container breeders, thus, container management is a key element for elimination of vector breeding sites. Use of predator fish is a potential tool for dengue vector control in some container habitats. However, in order to select suitable fish species, larvivorous potential of different fish species needs to be determined. Therefore, the objective of the study was to determine the larvivorous potential of some fresh water fish species against the dengue vectors. METHODOLOGY: Five fish species, namely: Poecilia reticulata, Aplocheilus dayi, Oreochromis niloticus, Rasbora daniconius and Puntius bimaculatus were collected from their natural breeding places during the field surveillance conducted from January-October, 2015. Each fish species was placed in separate fish stock cement tanks at the Regional Office of the Anti- Malaria Campaign in Kandy until they were used for the study. In order to determine the larvivorous potential of the fish, each species was placed in separate enamel trays containing de-chlorinated water and allowed to acclimatize for 30 minutes. A batch of 25 Ae. aegypti and Ae. albopictus larvae was introduced to each tray superlatively and the number of larvae remaining was counted after 24 hours of observation period. Once all the batch of larvae consumes by the fish species, another batch of 25 larvae from respective species was introduced during the observation period. The whole experiment was repeated for 6 times. RESULTS: The mean values of Ae. aegypti larvae consumed by one fish of O. niloticus, P. reticulata, A. dayi, R. daniconius and P. bimaculatus were 97.6, 66.9, 49.3, 62.5 and 47.5 respectively while, one fish of O. niloticus, P. reticulata, A. dayi, R. daniconius and P. bimaculatus consumed 98.4, 62.3, 51.2, 62.5 and 45.4 of mean Ae. albopictus larvae respectively. CONCLUSIONS: All five fish species showed larvivorous activity. However, O. niloticus showed the highest larvivorous potential followed by P. reticulata. Therefore, these two fish species may be considered as a supplementary method to control immature stages of dengue vectors.
Larvivorous potential of fish species found in river bed pools below the major dams in Sri Lanka
(Entomological Society of America, 2006) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.D.; Wijeyaratne, M.J.S.
Malaria in Sri Lanka is closely associated with the river systems in the country. Construction of major dams across rivers has resulted in year-round pooling and anopheline mosquito breeding in river beds below the dams. This study was carried out to determine the larvivorous activity of fish found inriver bed pools below the dams to identify the potential fish species for anopheline larval control in these areas. Fish species in five river beds below the dams, namely, Laxapana, Kotmale, Nilambe, Victoria, and Rantembe, were identified in June 2000. The larvivorous potential of the 12 fish species collected was determined in the laboratory based on the number of larvae consumed per fish within 10 min and an hour. Danio malabaricus Jerdon, Oreochromis mossambicus Peters, Oreochromis niloticus L., and Poecilia reticulata Peters consumed nine or more larvae per fish within 10 min. Aplocheilus dayi Steindachner and Rasbora daniconius Hamilton consumed nine and eight larvae, respectively, within 1 h. O. mossambicus, O. niloticus, and P. reticulata consumed 10 larvae per fish within 10 min. Despite some species having a high larvivorous potential in the laboratory, field studies are required to determine the feasibility of using these fish for anopheline mosquito control in the river bed pools below the dams
Larvivorous Potential of Four Fish Species Against Dengue Vectors in The Kandy District of Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Gunathilaka, P.A.D.H.N.; Hapugoda, M.D.; Abeyewickreme, W.
There is a growing concern on the effects of insecticides that are used for the control of mosquito vectors of human diseases. Introducing a self propagating predator into the vector breeding habitats may present continual biological control of vector population. In order to control dengue vectors, namely, Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) (Diptera: Culicidae), larval control is one of the major strategies. The objective of this study was to evaluate the larvivorous potential of fish species against dengue vectors. Four fish species, namely, Poecilia reticulata (guppy), Aplocheilus dayi (Udahandaya), Oreochromis niloticus (Tilapia) and Puntius bimaculatus were collected from natural breeding habitats. They were placed in fish stock cement tanks at the Regional Office of the Anti Malaria Campaign in Kandy till they were used for the study that was conducted from January – June 2015. In order to determine the larvivorous potential of the fish species, five fish of each species were placed in separate enamel trays containing de-chlorinated water and allowed to acclimatize for half an hour. Afterwards, a batch of 25 Ae. aegypti larvae was introduced to each tray and counted the number of larvae remaining after 5, 10, 30 minutes, 1 and 24 hours. When all 25 larvae are consumed, another batch of 25 larvae was introduced to those trays and this was continued till the study was completed. At the end of study period (24 hours), the number of larvae consumed per fish for each fish species was determined. This study was carried out in the laboratory with 6 replicates. The experiment was repeated for Ae. albopictus. Overall, Oreochromis niloticus, Poecilia reticulata, Aplocheilus dayi and Puntius bimaculatus consumed 97.6, 66.9, 49.3 and 47.5 Ae. aegypti and 98.4, 62.3, 51.2 and 45.4 Ae. albopictus larvae respectively. All four fish species showed larvivorous activity and Oreochromis niloticus showed the highest larvivorous potential followed by Poecilia reticulata. Since Ae. aegypti and Ae. albopictus breed in water storage containers such as cement tanks, barrels and ornamental ponds, the fish species that showed high larvivorous potential may be considered for dengue vector larval control in such containers. In order to achieve good community participation for the use of larvivorous fish for dengue vector control, effective health education is of utmost importance.
Larvivorous potential of the Guppy, Poecilia reticulata, in Anopheline mosquito control in river bed pools below the Kotmale dam, Sri Lanka
(SAGE Publishing, 2008) Kusumawathie, P.H.D.; Wickremasinghe, A.R.; Karunaweera, N.D.; Wijeyaratne, M.J.S.
The larvivorous potential of Poecilia reticulata was studied in the laboratory and in the field. In the laboratory, the number of anopheline larvae consumed per fish per day and the number of larvae in fecal matter per fish were determined. In the field study, 29 of 60 selected riverbed pools in Kotmale oya, below the Kotmale dam, were stocked with P reticulata, whereas the rest served as controls. Anopheline larval surveys were carried out starting from 1 day prior to stocking of fish and on selected days subsequently. P. reticulata consumed an average of 117 +/- 32.33 larvae per fish per day. Fecal matter of P. reticulata contained an average of 2.7 +/- 2.68 larvae per fish . There was a significant reduction in the number of pools positive for anopheline larvae (P < .001) after stocking fish and the number of larvae per pool (P < .001) and per 100 dips (P < .001) as compared with controls
Lavivorous Potential of Fish Species Found in River Bed Pools Below the Major Dams in Sri Lanka
(Vector-Borne Diseases,Surveillance,Prevention, 2006) Wijeyaratne, M.J.S.; Kusumawathie, P.H.D.; Wickremasinghe, A.R.; karunaweera, N.D.
Most productive and prevalent breeding habitats of Aedes aegypti and Ae. albopictus (pupae) in the Kandy and Nuwara Eliya districts of Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2007) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Wickremasinghe, A.R.
Breeding habitats of Aedes aegypti and Ae. albopictus in the Kandy and Nuwara Eliya districts were studied from April 2006 to April 2007. Surveys of Aedes aegypti and Ae. albopictus immatures were carried out in 101 localities in the Divisional Director of Health Services (DDHS) areas of Akurana, Doluwa, Gampola, Gangawatakorale, Hanguranketha, Kundasale, Medadumbara, Nawalapitiya, Pathadumbara, Pathahewaheta, Poojapitiya, Tumpane, Udunuwara, Werallagama, Yatinuwara and in the Kandy Municipal Council area. During each survey, all potential indoor and outdoor breeding habitats of Ae. aegypti and Ae. albopictus were examined. Aedes larvae and pupae, 10 of each, were randomly collected from each mosquito immature positive habitat by dipping, pipetting or straining (if a particular habitat had < 10 larvae/ pupae, all larvae/ pupae were collected). Larvae and emerged adults from pupae were identified using larval and adult identification guides. Twenty two (22) types of container habitats were positive for Ae. aegypti and Ae. albopictus larvae. Of these 14, were positive for Ae. aegypti and or Ae. albopictus pupae. Pupal container index (percentage of containers positive for Ae. aegypti and / or Ae. albopictus pupae) of different types of container habitats were: metal ware (11.59%), unprotected plastic tanks (8.33%), roof gutters (7.14%), tyres (5.69%), polythene bags/sheets (3.85%), ornamental ponds (2.97%), coconut shells (2.67%), refrigerator trays (1.87%), water storage barrels (1.73%), clay pots (1.48%), water storage cement tanks (1.41%), tins (0.75%), leaf axils (0.72%) and discarded plastic containers (0.60%). However, water storage cement tanks (35.09%), water storage barrels (18.45%), discarded plastic containers (15.43%), refrigerator trays (7.13%), clay pots (5.40%) and tyres (4.91%) constituted the majority (86.41%) of potential breeding sites of Ae. aegypti and Ae. albopictus. Management of mostly prevalent and pupae positive containers would reduce the adult Ae. aegypti and Ae. albopictus density and consequently the dengue and dengue haemorrhagic fever incidence in the Kandy and Nuwara Eliya districts.
Nocturnal human biting behavior of Anopheles culicifacies in a hydro electric power project area situated in a sylvatic environment in the Central Province of Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2007) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Abeyasinghe, R.R.; Wickremasinghe, A.R.
Nocturnal human biting behavior of Anopheles culicifacies was studied from January 2006 - March 2007 at the Victoria hydro electric power generation project area in the Central Province of Sri Lanka. Monthly collections of indoor and outdoor, landing and biting, mosquitoes were made from 1700 - 0600 hours (13 hours) using 3 - 4 indoor and 4 -8 outdoor human baits. In each collection, human baits were seated with exposed hands and legs below the knees. Hourly collections of landing and biting mosquitoes on the exposed surfaces of the body using torches and aspirators were made and mosquitoes were identified to species. Data was summarised as the number of An. culicifacies collected indoors and outdoors each hour/bait separately. The majority (97.83%) of An. culicifacies bit outdoors as compared to indoors. There were monthly variations in the biting habits with the highest densities being observed from February to April. An. culicifacies bit throughout the night with peak biting hours from 2200 - 2400 hours. Previous studies indicated that the peak biting hours were earlier in the evening and the morning. Further studies are required to study the nocturnal human biting behavior of An. culicifacies in other areas of Sri Lanka since this information is very important in planning malaria control activities. However, preventive measures directed to protect the outdoor workforce in the Victoria project should be a priority. If space spraying is planned, it should be carried out between 2200 - 2400 hours to cover the peak biting period of An. culicifacies in the project area.