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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 A Comparative field study of novel commercial Antigen Detection Enzyme-Linked Immunosorbent Assay (ELISA) with Reverse Transcription Polymerase Chain Reaction (RT- PCR) assay for early definitive laboratory diagnosis of dengue viral infection in Sri Lanka(Sri Lanka Association for the Advancement of Science, 2007) Hapugoda, M.D.; Jayasooriya, D.H.S.W.; Gunawardene, Y.I.N.S.; Wellawaththage, C.; Premaratna, R.; Abeyewickreme, W.Dengue is an important mosquito borne viral infection in South East Asia. Early definitive laboratory diagnosis of infection would help in management of patients and reducing the case fatality rate. The objective of this study was to determine the accuracy of novel commercial Antigen Detection Enzyme-Linked Immunosorbent Assay (ELISA) using Non Structural protein 1 (NS1) (Bio Rad) for early definitive laboratory diagnosis of dengue infection under field conditions in Sri Lanka. A panel of acute serum samples collected from 99 patients clinically suspected of having dengue fever (<5 days) warded at the North Colombo Teaching Hospital, Ragama, Sri Lanka were used for the present study. Serum samples were tested using Antigen Detection ELISA according to the method described by the manufacturer. Results of this novel assay were compared with RT-PCR assay using Chi-squared test. Two variables were analyzed at a 95% confidence interval and P value <0.05 was considered as significant. Twenty two and 65 patients were positive and negative, respectively, for dengue infection by both assays. Nine patients were confirmed as dengue by the Antigen Detection ELISA only. Three patients were confirmed as dengue by RT-PCR assay only. Antigen detection ELISA showed 88% of agreement with the RT-PCR assay. According to the Chi-squared test, there was no significant difference between the two assays for early diagnosis of dengue infection (?2=46, P=0.0000). Novel commercial Antigen Detection ELISA kit (Bio-Rad 72830) can be used for early definitive laboratory diagnosis of dengue infection in Sri Lanka under field conditions. Acknowledgement: the International Atomic Energy Agency (SRL 06/28) for technical co-operation and APCOT Marketing LTD, Sri Lanka for supplying Antigen detection ELISA kits.Item Large-scale entomological assessment of Wuchereria bancrofti transmission by dissection and PCR-ELISA in Gampaha district, Sri Lanka(Sri Lanka Association for the Advancement of Science, 2008) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Manamperi, A.; Hapuarachchi, H.A.C.; Bandara, K.B.A.T.; Abeyewickreme, W.Entomological surveys are important tools for monitoring progress of lymphatic filariasis (Lf) eradication programs. In this study, dissection of Culex quinquefasciatus was compared with a Polymerase Chain Reaction - Enzyme Linked Immunosorbent Assay (PCR-ELISA) for pooled mosquitoes to assess filarial infection levels in the major vector of Wuchereria bancrofti in Gampaha district, following mass-treatment programme with diethylcarbamazine (DEC) and albendazole. Mosquitoes were collected in 30 sentinel and 15 non-sentinel sites in 15 Medical Officer of Health (MOH) areas of Gampaha district known for the presence of W. bancrofti transmission. Captured mosquitoes were dissected to determine the W. bancrofti larvae (L1, L2, L3). PCR was carried out using Deoxyribonucleic acid (DNA) extracted from mosquito pools (15 body parts/pool) utilizing primers specific for the Wb-SspI repeat. PCR products were analyzed by hybridization ELISA using fluorescein-labeled wild type specific probes. The prevalence of infected/infective mosquitoes in PCR pools (3pools/site) was estimated using the PoolScreenTM algorithm and a novel probability-based method. The prevalence of infected mosquitoes with L1-L2 larvae of W. bancrofti ranged from 0%-8.54% by dissection and point estimates of infection prevalence as assayed by PCR-ELISA, ranged from 0% - 25.4%. Mosquitoes collected from all MOH areas (80%, N = 12), except for Minuwangoda, Dompe and Ragama, were positive for W. bancrofti larvae, with a prevalence rate ranging from 0.78% to 16.97% in both methods. Of 30 sentinel sites, 43.3% (N = 13) were positive for W. bancrofti transmission whereas it was evident in 40% (N = 6) of non-sentinel sites. The proportion of positive pools detected by the PCR-ELISA assay was higher than that obtained by the dissection indicating that PCR-ELISA assay is more sensitive than the dissection method in detecting infected/infective mosquitoes. Also results of this study showed that autochthonous transmission of W. bancrofti continues in the Gampaha district despite completion of the 5 year mass drug administration (MDA) programme. Therefore, we emphasize the use of more sensitive tools such as PCR-ELISA to monitor the impact of the MDA programme on disease transmission. This study also emphasizes that control measures should be further continued until the microfilareamic population is reduced to a level which could interrupt transmission in the area. Financial assistance received from WHO/SEARO/TDR (grant no. SN 1152) and University of Kelaniya (Grant no. RP/03/04/06/01/2006) is acknowledged