Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Shifting of circulating serotypes in dengue outbreaks during 2009/2010 in Sri lanka(Faculty of Tropical Medicine, Mahidol University, 2010) Manamperi, N.H.; Athapaththu, A.M.M.H.; Premawansa, G.; Wellawaththage, C.; Jayarathna, T. D. S. S.; Abeyewickreme, W.; Hapugoda, M.D.OBJECTIVES: Sri Lanka has experienced explosive outbreaks of dengue infection in 2009 and 2010. It has been identified that DEN- 3 and DEN- 2 were the predominant serotypes with DEN-1 and DEN- 4 circulating at a lower level in previous dengue outbreaks during 2003-2006, Objective of this study was to identify the circulating serotype/s during 2009 - 2010 outbreaks. METHODOLOGY: A prospective study was carried out at North Colombo Teaching Hospital, Sri Lanka during December 2009-August 2010. Clinically suspected dengue patients, with fever less than 5 days were recruited. An interviewer administered questionnaire was filled for each patient, by a Medical Officer. Venous blood samples confirmed for the presence of dengue virus by RT-PCR were typed by Semi-Nested PCR. RESULTS: Out of the 209 patients recruited in the study 80 (38%) were positive for dengue virus by RT-PCR. Of the positives, 43 (54%) were typed and circulation of all 4 serotypes was observed- Of the 43 positives, presence of DEN-1, DEN-2, DEN-3 and DEN-4 serotypes was 34 (79%), 3 (7%), 2 (5%) and 3 (7%) respectively DEN-1 was the predominant serotype in the recent epidemics which was circulating at a low level in previous epidemics. In DEN-1 infected patients, the mean platelet value was 58,588/ rnm3 and the mean PCV value was 41.4%. Associated symptoms such as headache, retro-orbital pain, neck pain and limb pain were present in 94% (32/34), 59% (20/34), 24% (8/34J and 91% (31/34) patients respectively. Bleeding manifestation developed in 47 % (16/34) patients. The mortality rate ranged from 0.7%- 1.0% during the recent outbreaks. Acknowledgement: Financial and technical assistance from the International Centre for Genetic Engineering and Biotechnology (ICGEB CRP/ SRI08-02) and the International Atomic Energy Agency (IAEA SRI 5/042) is gratefully acknowledged.Item Surveillance for dengue vector mosquito in Kurunegala district, Sri Lanka(Elsevier, 2008) Sumanadasa, S.D.M.; Hapugoda, M.D.; Peiris, I.; Perera, D.; Bandara, S.; Mansoor, M.A.C.M.; Abeyewickreme, W.BACKGROUND: Dengue vector surveillance is an important tool to determine the time and area/s to initiate control action. Our objective was to identify entomological risk factors with regard to transmission of dengue in a dengue hot-spot. METHODS: In the study 75 human dwellings in a dengue hot-spot in the District of Kurunegala was selected based on high disease incidence during 2000—2004, high Aedes as well as human population density and increased building activities. House to house mosquito surveillance was carried out from 08.00 am to 12.00 noon during May—August, 2007. Larvae and adult Aedes mosquitoes were collected indoors and outdoors using normal larval surveillance and human landing diurnal collection techniques respectively. Environmental and sociological data were obtained from households by interviewer administered questionnaires and observations. RESULTS: The house index for Aedes aegypti and Aedes albopictus ranged from 1.33%—6.60% and 2.67%—5.33% respectively. The Breatu index ranged between 23.67%—29.33% for Ae. aegypti and 1.33%—18% for Aedes albopictus. Man biting rates of 0.43—5.78 bites/man/hour were estimated for Ae. aegypti, while it ranged from 0.49—1.33 for Ae. albopictus. The most common breeding place for Aedes species was plastic baskets (16%, n = 12). More than half of the households (61%, n = 45) stored water in large cement tanks for their daily activities. Majority of the group (99%, n = 74) had a basic knowledge on dengue mosquito breeding places (97%, n = 73), their life cycle (95%, n = 71) and mode of transmission (99%, n = 74). Domestic waste of majority of households was carried away daily by the local authorities (n = 69). CONCLUSION: These results suggest that a vector control program should be adopted to reduce Aedes population levels below dengue transmission thresholds. Discarded containers of various types were identified as potential mosquitoes breeding habitats. Therefore, community must be educated on effective vector control measures to contain the transmission levels. © 2008 Elsevier Inc.Item Silent transmission of the dengue fever in Gampaha District, Sri Lanka(Malaysian Society of Parasitology and Tropical Medicine, 2007) Hapangama, H.A.D.C.; Gunawardene, Y.I.N.S.; Gunasena, S.; Hapugoda, M.D.; Premaratna, R.; Wellawaththage, L.C.; Abeyewickreme, W.Dengue fever is a major infectious disease in Sri Lanka. Silent transmission of dengue virus has been suggested as a possible risk factor for the increasing incidence of dengue. The present study was carried out in the District of Gampaha using cluster investigation method. A cluster consisted of a minimum of 20 volunteers (family members and immediate neighbours) of a hospitalized serologically/molecular biologically confirmed dengue patient. Serum samples were collected from 148 volunteers in 7 clusters. Samples were tested for anti-dengue antibodies using Dengue Duo IgM and IgG Rapid Strip Test. Of these, positives were further tested for anti-dengue IgG antibody by Haemagglutination Inhibition (HAI) assay, the gold standard test for serological diagnosis of virus infection. Of the 148, 41 had evidence of exposure to dengue virus by Dengue Duo IgM and IgG Rapid Strip Test [positive for IgM: 28(68.4%), IgM & IgG: 7(17%) and IgG: 6(14.6%)]. Of that 41, paired sera were collected from 36 volunteers and tested by HAI assay which confirmed dengue virus infection in 4(11.1%) [confirmed secondary-4(100%)]. Additional 32(88.9%) were diagnosed as recent dengue infections [probable secondary-17(53.1%), probable dengue- 15(46.9%)]. Out of 36 volunteers, 12(33.3%) were symptomatic [confirmed secondary-1(8.3%), probable secondary-10(83.4%), probable dengue-1(8.3%)] and 24(66.7%) were asymptomatic [confirmed secondary-3(12.5%), probable secondary-7(29.2%), probable dengue-14(58.3%)]. Presence of dengue vectors, Aedes aegypti and/or Aedes albopictus were detected around all 7 clusters. The present study serologically confirms the persistence of silent transmission of dengue virus with a trend towards clustering around cases. Presence of vector species in the area further supports this phenomenon.Item Occurrence of a dengue epidemic in Minipe valley of the Kandy district: evidence for Aedes albopictus being an epidemic vector of dengue in Sri Lanka(Sri Lanka Association for the Advancement of Science, 2011) Kusumawathie, P.H.D.; Jayasooriya, G.A.J.S.K.; Abeyewickreme, W.; Hapugoda, M.D.Item Effect of silent transmission and clustering of cases on transmission of dengue in Gampaha district(Sri Lanka Association for the Advancement of Science, 2007) Hapangama, H.A.D.C.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.; Premaratna, R.; Dayanath, M.Y.D.; Abeyewickreme, W.Silent transmission of dengue virus and clustering of cases have been suggested as possible factors for the increasing incidence of dengue fever. Objective of this study was to determine the presence of silent transmission and clustering of cases of dengue fever in the Gampaha District. Study was carried out using cluster investigation method. A cluster consists of family members and immediate neighbours (minimum of 20) of a dengue index-case. Serum samples from volunteers were tested for anti-dengue antibodies using Dengue-Duo-IgM/IgG Rapid Cassette (Panbio diagnostics, Australia). Using 7 index cases, 148 volunteers (68 Males); mean age: 35.9 years were enrolled. Of the 148, 41 had evidence of exposure to dengue virus [positive for IgM: 68.4% (28/41), IgM & IgG: 17% (7/41) and IgG: 14.6% (6/41)]. Out of 28 primary infections, 71.4% (20/28) were asymptomatic. Of the 7 secondary infections, 14.28% (1/7) was asymptomatic. Of the 6 previous exposures to dengue, 4 (66.67%) were asymptomatic. There was no significant association between sex and exposure to infection [31% (21/68) males vs 25% (20/80) females, p>0.05] or between sex and occurrence of symptoms among exposed individuals [71% (15/21) males vs 50% (10/20) females, p>0.05]. Older individuals aged over 40 years, were most likely to be asymptomatic than younger persons (94% (14/15 exposed) vs 50% (13/26 exposed), P<0.01). Out of 7 clusters investigated, 1 had >50%, 4 had >25% and 2 had <25% clustering effects. A high proportion of asymptomatic infections were observed among adults over 40 years without gender difference. Study suggests persistence of silent transmission of dengue virus with a trend towards clustering around cases. Acknowledgement: World Health Organization (WHO/SEARO SN1144) and technical co-operation by International Atomic Energy Agency (TC/SRL 06/28)Item Knowledge, attitudes and practices (KAP) on dengue control in Gampaha district.(Sri Lanka Association for the Advancement of Science, 2008) Abeyewickreme, W.; Hapangama, H.A.D.C.; Gunawardene, Y.I.N.S.; Hapugoda, M.D.; Gunawardena, N.K.; Wickremasinghe, A.R.Dengue/Dengue Hemorrhagic Fever (DHF) has become a major public health problem in many parts of the tropics. In Sri Lanka, it is endemic in some parts of the country with outbreaks of dengue/ DHF. The present study was done to assess 1) knowledge regarding dengue among the general population in the district of Gampaha, 2) whether simple preventive measures are being practiced in the community. A cross-sectional survey was conducted in selected 2000 households in the Gampaha District from June - August, 2007 using a pre-tested structured questionnaire to assess the level of knowledge, attitudes and practices regarding dengue. The majority of the respondents interviewed were females (65.2%). More than 90% have had secondary education (90.2%). The main source of water supply were pipe borne (43.4%) and well water (40.6%). 64.3% households stored water for washing, drinking and cleaning purposes. More than 95% of the respondents had heard about dengue fever and its transmission. 91.3% cited that their main source of information on dengue was from television/radio. 34.3% had either received advice or participated in a training programme on dengue prevention and 7.8% had received support materials. The main preventive measure used to reduce the mosquito nuisance was personal protection with repellents (73.6%). Most of the respondents (56.8%) felt that no action was taken by the government to control mosquitoes. When respondents views were taken, the suggestions made by them to improve dengue control included, fogging (31.8%), educating people (30.5%), treating water (24.3%) and cleaning the environment (19.5%). When questions were directed at possible methods for community participation for dengue control, the majority were in favour of removing solid waste (84.15%), eliminating stagnant water collections (40.7%), removing larvae (8.75%) and covering all the water containers using lids (8.1%). The community had good understanding on dengue and the main source of information was from the electronic media. However it was found that good knowledge itself does not necessarily lead to good practices. The respondents' attitudes were found to be good and most of them were supportive of control measures. Mass media is an important means of conveying health messages to the public, thus research and development of educational strategies designed to improve behaviour and practices of effective control measures through mass media among the community are recommended. Financial support by World Health Organization TDR/WHO Multi Country Study on "Eco-Bio-Social Research on Dengue in Asia" is acknowledged.