Journal/Magazine Articles

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This collection contains original research articles, review articles and case reports published in local and international peer reviewed journals by the staff members of the Faculty of Medicine

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Author: search.filters.author.Bandara, K.B.A.T.

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Now showing 1 - 5 of 5
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    Re emergence of Chikungunya virus in South-east Asia: virological evidence from Sri Lanka and Singapore
    (Cambridge University Press, 2010) Hapuarachchi, H.C.; Bandara, K.B.A.T.; Sumanadasa, S.D.; Hapugoda, M.D.; Lai, Y.L.; Lee, K.S.; Tan, L.K.; Lin, R.T.; Ng, L.F.; Bucht, G.; Abeyewickreme, W.; Ng, L.
    Chikungunya fever swept across many South and South-east Asian countries, following extensive outbreaks in the Indian Ocean Islands in 2005. However, molecular epidemiological data to explain the recent spread and evolution of Chikungunya virus (CHIKV) in the Asian region are still limited. This study describes the genetic Characteristics and evolutionary relationships of CHIKV strains that emerged in Sri Lanka and Singapore during 2006-2008. The viruses isolated in Singapore also included those imported from the Maldives (n=1), India (n=2) and Malaysia (n=31). All analysed strains belonged to the East, Central and South African (ECSA) lineage and were evolutionarily more related to Indian than to Indian Ocean Islands strains. Unique genetic characteristics revealed five genetically distinct subpopulations of CHIKV in Sri Lanka and Singapore, which were likely to have emerged through multiple, independent introductions. The evolutionary network based on E1 gene sequences indicated the acquisition of an alanine to valine 226 substitution (E1-A226V) by virus strains of the Indian sublineage as a key evolutionary event that contributed to the transmission and spatial distribution of CHIKV in the region. The E1-A226V substitution was found in 95.7 % (133/139) of analysed isolates in 2008, highlighting the widespread establishment of mutated CHIKV strains in Sri Lanka, Singapore and Malaysia. As the E1-A226V substitution is known to enhance the transmissibility of CHIKV by Aedes albopictus mosquitoes, this observation has important implications for the design of vector control strategies to fight the virus in regions at risk of chikungunya fever.
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    Laboratory confirmation of dengue and chikungunya co-infection
    (Sri Lanka Medical Association, 2008) Hapuarachchi, H.A.C.; Bandara, K.B.A.T.; Hapugoda, M.D.; Williams, S.; Abeyewickreme, W.
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    Point mutations in the dihydrofolate reductase and dihydropteroate synthase genes of Plasmodium falciparum and resistance to sulfadoxine-pyrimethamine in Sri Lanka
    (American Society of Tropical Medicine and Hygiene, 2006) Hapuarachchi, H.A.C.; Dayanath, M.Y.D.; Bandara, K.B.A.T.; Abeysundara, S.; Abeyewickreme, W.; de Silva, N.R.; Hunt, S.Y.; Sibley, C.H.
    Sulfadoxine-pyrimethamine (SP) is the second-line treatment for Plasmodium falciparum malaria in Sri Lanka. Resistance to SP is caused by point mutations in the dihydrofolate reductase (Pf-dhfr) and dihydropteroate synthase (Pf-dhps) genes of P. falciparum. We determined the genotype of Pf-dhfr and Pf-dhps and the clinical response to SP in 30 field isolates of P. falciparum from Sri Lanka. All patients treated with SP had an adequate clinical response. Eighty-five percent (23 of 27) of pure field isolates carried parasites with double mutant alleles of Pf-dhfr (C59R + S108N) and showed about 200-fold higher levels of resistance to pyrimethamine than the wild type in a yeast system. None of the isolates had either known or novel mutations at other positions in the dhfr domain. In contrast, 67% (20 of 30) of the isolates carried parasites that were wild type for Pf-dhps. In Sri Lanka, detection of the triple mutant allele of Pf-dhfr will require tracking mutations at codon 51
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    Chloroquine resistant falciparum malaria among security forces personnel in the Northern Province of Sri Lanka
    (Sri Lanka Medical Association, 2004) Hapuarachchi, H.A.C.; Dayanath, M.Y.D.; Abeysundara, S.; Bandara, K.B.A.T.; Abeyewickreme, W.; de Silva, N.R.
    OBJECTIVE: To determine the occurrence and species distribution of malaria and the extent of chloroquine resistance among security forcespersonnel in a selected region of the Northern Province of Sri Lanka. DESIGN: A descriptive study. SETTING: Mannar District in the Northern Province. METHODS: Nine hundred and seventy five security personnel were screened for malaria by microscopy. Those who were positive were treated withchloroquine and were subjected to 28 day in vivo assay to determine chloroquine resistance. In vitro microtest assay was performed to determine the response of Plasmodium falciparum isolates to chloroquine in vitro. RESULTS: Of the 975 personnel screened, 181 (18.6%) were positive for malaria. P. falciparum was the predominant species (n = 125; 69.1%). The rest were due to P. vivax (n = 42; 23.2%) and mixed infections (n = 14; 7.7%). This was an inversion of the usual species distribution pattern in the country. In vivo assay revealed 38 (53.5%) P. falciparum infections as chloroquine resistant. Fifteen of 23 (65.2%) P. falciparum isolates showed evidence of resistance in vitro. None of the P. vivax infections showed evidence of chloroquine resistance. There was no significant difference in the severity of clinical disease between chloroquine resistant and sensitive infections at first presentation. Recrudescent P. falciparum infections had significantly lower mean parasite densities as well as lower clinical scores at recrudescence than at first presentation. CONCLUSION: Results demonstrate the high prevalence of malaria and chloroquine resistance in the study area and explains several contributory factors for this. There is an urgent need to review antimalarial drug policies in Sri Lanka
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    A Novel reverse transcriptase-polymerase chain reaction based-liquid hybridisation(RT-PCR-LH) assay for early diagnosis of dengue infection
    (Sri Lanka Medical Association, 2003) Gunasekera, M.B.; Hapugoda, M.D.; Gunasena, S.; Subasinghe, S.A.S.C.; Bandara, K.B.A.T.; Khan, K.B.; Abeyewickreme, W.
    BACKGROUND: Early definitive laboratory diagnosis of dengue is difficult with the tests in routine use at present. OBJECTIVE: To develop a reverse transcriptase-polymerase chain reaction based liquid hybridisation (RT-PCR-LH) technique for the rapid and early diagnosis of dengue. RESEARCH DESIGN: RT-PCR products of the NS3 gene of dengue virus prototypes and of a few positive sera for dengue virus by culture, were allowed to hybridise in liquid phase with a mixture of dengue specific radio-labelled oligonucleotides. The products were separated by PAGE and visualised by autoradiography. 78 suspected dengue sera were also tested by RT-PCR-LH method, and by IgM-ELISA and HAI tests, for comparison. RESULTS: Two DNA bands (approximately equal to 470 bp and approximately equal to 455 bp) specific to dengue virus, were observed. RT-PCR-LH assay takes only 24 h. Of the 78 suspected dengue acute sera tested, 45/78 were positive by RT-PCR-LH, 31/78 were positive by IgM-ELISA, and 14/78 had a HAI titre > or = 2560. Duration of fever was known in 72 cases, and infection was detected by RT-PCR-LH in 11/22 of cases with < 5 d fever and by IgM-ELISA in 1/22. In cases with 5 to 15 d fever RT-PCR-LH and IgM-ELISA/HAI titre > or = 2560 detected infection in 30/50 and 27/50 respectively. The 10 sera which were negative by RT-PCR-LH, but were positive by either IgM-ELISA or HAI titre > or = 2560 were all > 5 d fever cases. RT-PCR-LH together with IgM-ELISA were capable of detecting dengue infection in 56/78 of the suspected cases. CONCLUSION: RT-PCR-LH assay developed in this study appears to have an advantage over other diagnostic techniques for the early detection of dengue.