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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Polymerase Chain Reaction and mosquito dissection as tools to monitor filarial Infection levels following mass treatment in Gampaha District, Sri Lanka(Elsevier, 2008) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Manamperi, A.; Bandara, K.B.A.T.; Liyanage, T.; Abeyewickreme, W.BACKGROUND: Mass Drug Administration (MDA)-based Global Lymphatic filariasis (Lf) eradication programmes are aimed at stopping transmission of Wuchereria bancrofti by its mosquito vector. The study was designed to compare one year post treatment (mass distribution of Diethylcarbamazine-Albendazole) infection rates of Wuchereria bancrofti in Culex quenquifaciatus, the main vector of Lf in Sri Lanka using Conventional dissection techniques and a Polymerase Chain Reaction (PCR) assay based on parasite specific Ssp1 repeat which amplifies a fragment of 188 bp. METHODS: Field study was conducted in 45 sites in all Medical Officer of Health (MOH) areas in the Gampaha district, Sri Lanka; identified by the Anti Filariasis Campaign (AFC) as having high-risk for bancroftian filariasis transmission. Indoor-resting mosquitoes were collected by aspiration from 20 houses per each site. Part of the mosquitos were used for dissection and the remainder was used for PCR to detect the filarial parasites in mosquito. RESULTS: Mosquito dissection data revealed 42.22% (19/45) of the sites were infested with mosquitoes positive for Wuchereria bancrofti, indicating 8 transmission active MOH areas (53.33%; 8/15). An infection rate of 5.26% was observed among the mosquitoes caught from households and the larval density was 8.7 per positive mosquito. PCR investigation revealed that 46.67% (21/45) of the sites were positive for W. bancrofti DNA, indicating 11 transmission active areas (73.33%; 11/15). The PCR was found to be more sensitive compared to microscopy in detecting the filarial parasite in field collected mosquito samples with respect to the MOH areas. CONCLUSION: The PCR technique employed offers scope for detection of the filarial parasites with higher sensitivity and specificity; is efficient and rapid. This technique applied for the first time in Sri Lanka, can be adopted as a diagnostic tool for the detection of filarial parasites in the vector population in surveillance to enable effective control of filariasis in the country. Acknowledgements: Authors acknowledge the WHO/SEARO/TDR (grant no. SN 1152) and University of Kelaniya (Research grant no. RP/03/04/06/01/2006) and to Ms. H.M.Renuka and Mr. H.P.Anura U. Pathirana, Mr. M.I.M.Peris and Mr. Y.L.Rassapana for their support during field study activities. © 2008 Elsevier Inc.Item Confirmation of 2006 chikungunya outbreak in Sri Lanka using RT-PCR(Malaysian Society of Parasitology and Tropical Medicine, 2007) Abeyewickreme, W.; Bandara, K.B.A.T.; Perera, H.; Dayanath, M.Y.D.; Hapuarachchi, C.Chikungunya, a mosquito-borne viral infection caused by a single-stranded RNA virus of the family Togaviridae, is considered as a rare, non-fatal disease. During February to October 2006, an epidemic of over 1.3 million suspected cases was reported in India and neighbouring countries causing a significant economic loss due to crippling manifestations of this infection. With the outbreak of many viral fevers including dengue and dengue haemorrhagic fever, in October–November 2006, patients with manifestations suggestive of chikungunya such as high fever, headache, arthralgia and arthiritis (particularly, in ankle, knee and small joints of hands) were reported in many parts of Sri Lanka. As no chikungunya cases had been officially reported in the island since 1969, laboratory investigations for the presence of chikungunya virus was a prime requirement for confirmation of the outbreak. A total of 60 venous blood samples collected from suspected patients from different geographical regions of Sri Lanka were analysed using a reverse transcriptase-polymerase chain reaction (RT-PCR) technique to confirm the presence of chikungunya virus. Viral RNA was extracted from samples collected within 1-4 days of fever by using a Qiagen RNA extraction kit. RT-PCR was performed using chikungunya specific oligonucleotides. Both positive and negative controls were included in each set of reactions. The amplified products (354 bp) were visualized by running in a 1.5% agarose gel followed by ethidium bromide staining. Of the 60 samples, 33 (55%) were positive for chikungunya. They were distributed among almost all the geographical regions, highlighting the presence of a wide-spread epidemic in the country.Item Chikungunya outbreak in 2008 in Ratnapura district, Sri Lanka - clinical and socio-economic analysis(Sri Lanka Association for the Advancement of Science, 2008) Sumanadasa, S.D.M.; Hapuarachchi, C.; Bandara, K.B.A.T.; Wellawaththage, L.C.; Abeyewickreme, W.Since 2006, Sri Lanka has experienced several outbreaks of chikungunya fever (CHIK) affecting several thousands of people. Today, CHIK has become one of the most important vector-borne diseases in the country. The objective of this study was to analyse the clinical manifestations and socio-economic status among CHIK patients reported from Pallebedda and Godakawela areas in Ratnapura district during the outbreak in February and March 2008. After obtaining the informed written consent, venous blood samples were collected from 80 suspected patients. A medical officer carried out clinical examination of each patient. Clinical information along with socio economic data of the patients was recorded in an interviewer-administered questionnaire. Serum samples were tested for CHIK by a Reverse-Transcription Polymerase Chain Reaction (RT-PCR) assay. Of eighty patients tested, 51% (n=42) were positive for CHIK. All positive patients had fever for less than 5 days duration. Majority of them (95%, n=40) had severe arthralgia with arthritis of small joints of hands and feet (81%, n=34). Moreover, a generalized, Itchy maculopapular rash was present in 78% (n=33) of them. The appearance of skin rash only after 4-5 days of fever was characteristic in the majority of patients. The mean age of positive patients was 38 years and consisted of 48% (n=20) of males. Many (43%, n=18) of them were farmers having a mean monthly family income of Rs. 4867.00. Analysis of educational status revealed that 60% (n=26) of family members had educated up to G.C.E. O/L whereas only 26% (n=12) had completed G.C.E. A/Ls. Twenty eight (67%) positive patients had at least one or more CHIK infected family members in addition. Moreover, 95% (n=40) of them were surrounded by infected neighbours indicating active, intense transmission in the area. According to the results, the most predominant clinical features of CHIK were fever either with severe arthralgia or arthritis of small joints of hands and feet. Skin rash, though characteristic, appeared to develop 4-5 days after the infection. CHIK has mainly affected the most productive labour force in these areas with majority belonging to the middle class farming community with a low monthly income. Hence, the sources of income of the affected families were severely hampered by the CHIK outbreak. Therefore, non-fatal, CHIK may have a negative impact on the socio-economic status of the affected communities. "The staff of the Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Dr Richard Perera and the staff of Godakawela Hospital and Dr. Susanth Kariyawasam and the staff of Pallebadda Hospital are acknowledged".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