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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty

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Author: search.filters.author.Abeyewickreme, W.End date: 1999

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Now showing 1 - 10 of 26
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    Potential use of IGR Pyriproxifen for control of dengue vector Aedes albopictus
    (Sri Lanka College of Microbiologists, 1999) Gunawardene, Y.I.N.S.; de Silva, N.R.; Abeyewickreme, W.
    Dengue Fever (DF) Dengue Haernorrhagic Fever (DHF) is now a significant problem in Sri Lanka. The incidence of DHF has increased cyclically since the first recognized outbreak in 1989. Of the 203 suspected DHF cases recorded in 1989, 87 were confirmed and 26 deaths were reported. By 1997, 5882 clinical cases, 1558 serologically confirmed cases and over 300 deaths have been reported. Without an effective vaccine against dengue, and considering the clinical difficulty in managing DHF cases, vector control has become an important com¬ponent in the integrated attempts for dengue con¬trol. Aedes aegypti and Aedes albopictus not only transmit dengue but are also a nuisance and cause annoyance by their day biting behaviour. In this study an attempt was made to control Ae. albopictus by exploiting its oviposition behaviour, us¬ing an Insect Growth Regulator (IGR), Pyriproxifen. The IGR is known to interfere with the synthesis and deposition of chitin in insects and thereby prevent growth and development. Different concentrations of the IGR (0.01 g/1 -0.08g/1) were tested against Ae.albopictus, in laboratory experiments. The most effective larvisidal concentration of Pyriproxifen for Ae.albopictus was determined to be 0.03g/1. Field trials were also carried out to determine the feasi¬bility of employing used automobile tyres contain¬ing Pyriproxifen as ovitraps against Ae.albopictus. Tyres containing water were treated with Pyriproxifen (0.03g/1) and the emergence of adults was recorded. Pyriproxifen at a concentration of 0.03g/1 was found to inhibit the emergence of adult Aedes mosquitoes up to 6 weeks.
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    Established, emerging and potential parasitic zoonoses in Sri Lanka
    (Elsevier, 1998) Abeyewickreme, W.; Wijesundara, M.; Weerasooriya, M.M.V.; Naotunna, T. de S.; de Silva, N.R.; Ismail, M.M.; Dissanaike, A.S.
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    Seasonal Trends of Anopheles Culicifacies population at Gomadiyagala, a village in a North Western Province of Sri Lanka
    (University of Sri Jayewardenepura, 1998) de Silva, B.G.D.N.K.; Gunasekera, M.B.; Abeyewickreme, W.; Wickremasinghe, M.B.
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    Screening of Anopheles crlicifacies population of Sri Lanka for sibling species A.
    (Thacker's Press and Directories for Indian Research Fund Association, 1998) de Silva, B.G.D.N.K.; Gunasekera, M.B.; Abeyewickreme, W.; Abhayawardena, T.A.; Karunanayake, E.H.
    A total of 1119 Anopheles culicifacies mosquitoes collected from various malaria endemic regions in Sri Lanka were examined using two DNA probes Rp217 and Rp234, which enable the differentiation of sibling species A from B and C species of An. culicifacies. Sibling species A was found to be absent.
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    Second case of ocular parastrongyliasis from Sri Lanka
    (Oxford University Press, 1998) Wariyapola, D.; Goonesinghe, N.; Priyamanna, T.H.H.; Fonseka, C.; Ismail, M.M.; Abeyewickreme, W.; Dissanaike, A.S.
    No Abstract available
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    Efficacy of single dose combinations of albendazole, ivermectin and diethylcarbamazine for the treatment of bancroftian filariasis
    (Oxford University Press, 1998) Ismail, M.M.; Jayakody, R.L.; Weil, G.J.; Nirmalan, N.; Jayasinghe, K.S.A.; Abeyewickreme, W.; Sheriff, M.M.R.; Rajaratnam, H.N.; Amarasekera, N.; de Silva, D.C.; Michalski, M.L.; Dissanaike, A.S.
    In a 'blind' trial on 50 male asymptomatic microfilaraemic subjects with Wuchereria bancrofti infection, the safety, tolerability and filaricidal efficacy of a single dose of albendazole (alb) 600 mg alone or in combination with ivermectin (iver) 400 microg/kg or diethylcarbamazine citrate (DEC) 6 mg/kg was compared with a single dose of the combination DEC 6 mg/kg and iver 400 micro g/kg over a period of 15 months after treatment. All but one subject, with 67 micro filariae (mf)/mL, had pre-treatment counts 100 mf/mL. All 4 treatments significantly reduced mf counts, but alb/iver was the most effective regimen for clearing mf from night blood: 9 of 13 subjects (69 percent) were amicro filaraemic by membrane filtration 15 months after treatment compared to one of 12 (8 percent), 3 of 11 (27 percent), and 3 of 10 (30 percent) in the groups treated with alb, alb/DEC, and DEC/iver, respectively. Filarial antigen tests suggested that all 4 treatments had significant activity against adult W. bancrofti; alb/DEC had the greatest activity according to this test, with antigen levels decreasing by 77percent 15 months after therapy. All 4 regimens were well tolerated and clinically safe, although mild, self-limited systemic reactions were observed in all treatment groups. These results suggest that alb/iver is a safe and effective single dose regimen for suppression of micro filaraemia in bancroftian filariasis that could be considered for control programmes. Additional benefits of this combination are its potent, broad spectrum activity against intestinal helminths and potential relative safety in areas of Africa where DEC cannot be used for filariasis control because of co-endemicity with onchocerciasis or loiasis
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    Established, emerging and potential parasitic zoonoses in Sri Lanka
    (Elsevier, 1998) Abeyewickreme, W.; de Wijesundara, M.; Weerasooriya, M.V.; Naotunne, T.de S.; de Silva, N.R.; Ismail, M.M.; Dissanaike, A.S.
    No abstract available
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    Human dirofilariasis caused by Dirofilaria (Nochtiella) repens in Sri Lanka
    (Roma, Istituto di Parassitologia, Città Universitaria, 1997) Dissanaike, A.S.; Abeyewickreme, W.; Wijesundera, M. de S.; Weerasooriya, M.V.; Ismail, M.M.
    Human dirofilariasis due to Dirofilaria (Nochtiella) repens is a common zoonotic infection in Sri Lanka. Todate 70 cases are on record, and they include 3 expatriates from Russia, England and Korea, who were undoubtedly infected in Sri Lanka. Around 30-60% of dogs are infected with D. repens in various parts of the country and the mosquito vectors are Aedes aegypti, Armigeres subalbatus, Mansonia uniformis and M. annulifera. Unlike in other countries of the old world infection is most common in children under the age of 9 years, the youngest being 4 months old and the scrotum, penis and perianal regions of male children appear to be frequent sites for the worms. Dirofilaria (Dirofilaria) immitis is not present in Sri Lanka though it is present in neighbouring countries like India, and Malaysia.
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    Prolonged clearence of microfilaraemia in patients with bancroftian filariasis after multiple high doses of ivermectin of diethylacarbamizine
    (Oxford University Press, 1996) Ismail, M.M.; Weil, G.J.; Jayasinghe, K.S.A.; Premaratne, U.N.; Abeyewickreme, W.; Rajaratnam, H.N.; Sheriff, M.M.R.; Perera, C.S.; Dissanaike, A.S.
    In a double-blind trial on 37 asymptomatic microfilaraemic subjects (minimum 400 microfilariae [mf] per mL) with Wuchereria bancrofti infection, the safety, tolerability and macrofilaricidal efficacy of 12 fortnightly doses of ivermectin, 400 microg/kg (ivermectin group), was compared with 12 fortnightly doses of diethylcarbamazine (DEC), 10 mg/kg (DEC group), over a period of 129 weeks after treatment. A control group (LDIC group) was treated with low dose ivermectin to clear microfilaraemia, for ethical reasons. Both ivermectin and DEC in high multiple doses were well tolerated and clinically safe. Macrofilaricidal efficacy was assessed by prolonged clearance of microfilaraemia, appearance of local lesions, and reduction of circulating W. bancrofti adult antigen detected by an antigen capture enzyme-linked immunoassay based on the monoclonal antibody AD12. Mf counts fell more rapidly after ivermectin than after DEC, but low residual mf levels were equivalent in these groups after week 4. Conversely, filarial antigen levels fell more rapidly after DEC than after ivermectin, but low residual antigen levels in these groups were statistically equivalent at all times beyond 12 weeks. Mild, self-limited systemic reactions to therapy were observed in all 3 treatment groups. Local reactions, such as development of scrotal nodules, were observed in several subjects in the DEC and ivermectin groups. These results suggested that high dose ivermectin and DEC both had significant macrofilaricidal activity against W. bancrofti, but neither of these intensive therapeutic regimens consistently produced complete cures. Thus, new drugs or dosing schedules are needed to achieve the goal of killing all filarial parasites in the majority of patients.
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    Development of DNA probes for the identification of sibling species A of the Anopheles culicifacies(Diptera Culicidae) Complex
    (CABI Publishing, 1995) Gunasekera, M.B.; de Silva, B.G.D.N.K.; Abeyewickreme, W.; Subbarao, S.K.; Nandadasa, H.G.; Karunanayake, E.H.
    Three highly repetitive DNA sequences, Rp36, Rp217 and Rp234, were isolated from A. culicifacies s.l. The cloned DNA sequences were found at a higher copy number in species B and C, than in species A of the A. culicifacies complex. These sequences may therefore be used as DNA probes to distinguish species A from the other 2 species, using a 200-fold dilution of a single mosquito DNA extract in a dot-blot hybridization assay. Rp36 and Rp217 were completely sequenced. Internal repeats were absent in Rp36. Two related core sequences of 134 and 16 bp were found tandemly repeated in Rp217. These probes enable the rapid detection of species A of A. culicifacies in field investigations
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