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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Silent transmission as a risk factor affecting transmission of dengue fever.(Faculty of Veterinary Medicine and Animal Science, University of Peradeniya, 2007) Hapangama, H.A.D.C.; Hapugoda, M.D.; Gunawardene, Y.I.N.S.; Premaratna, R.; Dayanath, M.Y.D.; Abeyewickreme, W.The global incidence of dengue fever has increased by more than four-folds over the last 30 years, making it the most threatening mosquito-borne viral disease at present. Objective of this study is to determine the role of silent transmission •on' incidence of dengue. A total of 40 households, living within a 300 m radius of seven selected ‘confirmed dengue cases at different dengue high risk localities in Gampaha District were recruited for this study. A minimum of three inhabitants were tested for anti-dengue antibodies using a commercial kit to determine the prevalence of silent transmission on dengue infection in each households. Entomological surveillance was carried out in all seven localities. Out of 40 households, 26 (65%) houses were positive for dengue viral infection. Total of 148 inhabitants (68 Males); mean age; 35.9 years were enrolled. Of the 148, 41 (27.7%) had evidence of exposure to dengue virus [positive for IgM: 28/41(68.4%), IgM'& IgG: 7/41(17%) and IgG: 6/41(14.6%)]. Out of 28 primary infections, 20(71.4%) were asymptomatic. Of the 7 secondary infections, 1(14.28%) was asymptomatic. Of the 6 previous exposures to dengue 4(66.67%) were asymptomatic. Of the 7 localities investigated, 1 had >50%, 4 had >25% and 2 had <25% clustering of cases. Ae. albopictus found in all seven localities and Ae. aegypti found only in two localities. This study suggests presence of silent transmission of dengue virus with a trend towards clustering around cases and also this shows that the presence of vectors increases the incidence of dengue.Item Ovi-trap based surveillance for Aedes in dengue endemic Gampaha District, Sri Lanka during rainy season(Faculty of Tropical Medicine, Mahidol University, 2008) Hapangama, H.A.D.C.; Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Benjamin, S.; Abeyewickreme, W.Dengue is endemic in Gampaha District, Sri Lanka. Aedes aegypti and Aedes albopictus have been incriminated as vectors in urban and suburban environments. An ovitrap-based weekly surveillance was carried out to determine the distribution and abundance of Dengue vectors, in six dengue endemic areas; Galudupita, Gongitota, Wanawasala, Kerangapokuna, Mabole and Welikadamulla in the Gampaha District during May and June 2008 in both indoors and outdoors. Galudupita and Gongitota gave the highest ovitrap indices, both indoors and outdoors as 97% and 73% respectively. Of the total positive ovitraps(1320), positivity for Ae. albopictus, Ae. aegypti and both were 63.5%, 32.9% and 3.6% respectively. Highest mean number of Ae. aegypti and Ae. albopictus larvae per ovitrap in both indoor and outdoor ovitraps were observed Galudupita and Gongitota respectively. However, statistical analysis showed that ovitrap index of Ae. aegypti in six study was not significantly different from each other (P > 0.05). Outdoor mean number of Ae. aegypti larvae per ovitrap in Galudupita, was significantly higher than other sites (F=3.587, P=0.012). Indoor Ae. albopictus ovitrap index of Gongitota was significantly higher than of Welikadamula (F=2.59, P=0.046) while outdoor Ae. albopictus ovitrap index of Gongitota and Wanawasala was significantly higher than of Welikadamula F=3.19 P=.0.02). Results irnplicate that Ae. albopictus prefers more vegetation as observed in Gongitota and Wanawasala. In highly populated and urbanized Galudupita, area with less vegetation, Ae. albopictus population was less than Ae. aegypti even outdoors. Study implicates that Ae. albopictus is the predominant indoor and outdoor breeder during rainy season.