Conference Papers

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This collection contains abstracts of conference papers, presented at local and international conferences by the staff of the Faculty of Medicine

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Author: search.filters.author.Premaratna, R.Subject: search.filters.subject.Dengue-epidemiology

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    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.
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    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)