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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 The Costs and cost-cffectiveness of mass treatment for intestinal nematode worm infections using different treatment thresholds(Public Library of Science, 2009) Hall, A.; Horton, S.; de Silva, N.BACKGROUND: It is estimated that almost a half of all of people living in developing countries today are infected with roundworms, hookworms, or whip worms or combinations of these types of intestinal nematode worms. They can all be treated using safe, effective, and inexpensive single-dose generic drugs costing as little as USD 0.03 per person treated when bought in bulk. The disease caused by intestinal nematodes is strongly related to the number of worms in the gut, and it is typical to find that worms tend to be aggregated or clumped in their distribution so that <20% of people may harbour >80% of all worms. This clumping of worms is greatest when the prevalence is low. When the prevalence rises above 50%, the mean worm burden increases exponentially, worms are less clumped, and more people are likely to have moderate to heavy infections and may be diseased. Children are most at risk. For these reasons, the World Health Organization (WHO) currently recommends mass treatment of children > or =1 year old without prior diagnosis when the prevalence is > or =20% and treatment twice a year when the prevalence is > or =50%. METHODS AND FINDINGS: The risk of moderate to heavy infections with intestinal nematodes was estimated by applying the negative binomial probability distribution, then the drug cost of treating diseased individuals was calculated based on different threshold numbers of worms. Based on this cost analysis, a new three-tier treatment regime is proposed: if the combined prevalence is >40%, treat all children once a year; >60% treat twice a year; and >80% treat three times a year. Using average data on drug and delivery costs of USD 0.15 to treat a school-age child and USD 0.25 to treat a pre-school child (with provisos) the cost of treating children aged 2-14 years was calculated for 105 low- and low-middle-income countries and for constituent regions of India and China based on estimates of the combined prevalence of intestinal nematode worms therein. The annual cost of the three-tier threshold was estimated to be USD 224 million compared with USD 276 million when the current WHO recommendations for mass treatment were applied. CONCLUSION: The three-tier treatment thresholds were less expensive and more effective as they allocated a greater proportion of expenditures to treating infected individuals when compared with the WHO thresholds (73% compared with 61%) and treated a larger proportion of individuals with moderate to heavy worm burdens, arbitrarily defined as more than 10 worms per person (31% compared with 21%).Item Controlling lymphatic filariasis and soil-transmitted helminthiasis together in South Asia: opportunities and challenges(Oxford University Press, 2006) Padmasiri, E.A.; Montresor, A.; Biswas, G.; de Silva, N.R.Item Making the best of what we have: a plea for wider use of anthelmintics(Indian Council of Medical Research, 2005) de Silva, N.No Abstract AvailableItem Impact of mass chemotherapy on the morbidity due to soil-transmitted nematodes(Elsevier, 2003) de Silva, N.R.This review summarises current knowledge of the ill-effects of soil-transmitted helminthiasis and takes a detailed look at studies that have been published over the past decade describing the effect of mass anthelminthic use on the health of endemic communities. Mass chemotherapy appears to give maximal returns in terms of improved health in areas where hookworm is a major problem and albendazole is used regularly, along with iron supplements; in children it improves physical growth and iron stores, and in pregnant women it reduces the prevalence of iron-deficiency anaemia. In areas where ascariasis is common, the directly attributable benefits of chemotherapy may be minimal, but it can facilitate the entry of other health care programmes in children, because deworming for ascariasis is often much desired and appreciated by the community. In areas with Vitamin A deficiency and endemic ascariasis, Vitamin A supplementation can be combined with deworming: anthelminthics do not impair Vitamin A absorption but the worms may interfere with Vitamin A uptake by reducing fat absorption. Where trichuriasis is a major problem, single dose chemotherapy may take some time to reduce prevalence, but reduction of heavy infections will reduce the incidence of Trichuris Dysentery Syndrome, probably benefit the learning abilities of affected schoolchildren, and may reduce anaemia and stunting. In general, children should be treated as early as possible, and in areas of very high prevalence, thrice-yearly mass chemotherapy probably improves health better than twice-yearly treatment.Item New policies for using anthelmintics in high risk groups(Elsevier, 2002) Allen, H.; Crompton, D.W.T.; de Silva, N.R.; LoVerde, P.T.; Olds, G.R.The 'Informal Consultation on the Use of Praziquantel during Pregnancy/Lactation, and Albendazole/Mebendazole in Children under 24 Months' was held 8-9 April 2002, in Geneva, Switzerland.Item Geo-helminth infections in a rural area of Sri Lanka(SEAMEO Regional Tropical Medicine and Public Health Project, 2001) Fernando, S.D.; Goonethilleke, H.; Weerasena, K.H.; Kuruppuarachchi, N.D.; Tilakaratne, D.; de Silva, D.; Wickremasinghe, A.R.School children carry the heaviest burden of morbidity due to intestinal helminth infection. The objective of this investigation was to study geo-helminth infections in 349 school children aged 6 to 13 years living in a rural area of Sri Lanka. Stool samples were examined by direct saline smear in an initial survey to determine the prevalence of intestinal parasitic infections and thereafter the children were followed up over a two year period with cross sectional surveys of stool samples being carried out at yearly intervals. Following collection of a stool sample, all the subjects were treated with mebendazole 500 mg as a single dose. Weights and heights were measured using standardized procedures. 2 ml of venous blood were collected from each subject under aseptic conditions to determine hematological indices. The prevalence of geo-helminth infections was low, and the prevalence declined during the two-year period from 5.4 percent in 1997 to 2.2 percent in 1998 and 2.0 percent in 1999 following yearly mass anti-helminth treatment. The incidence density was 0.021 cases per child year. The reduction in the prevalence from the baseline to the second survey is probably due to the reduction of the reservoir of infection among children as a result of mass treatment at baseline. The prevalence of infection during the second and third surveys were almost the same probably due to infections originating from other segments of the untreated population.Item Intestinal helminth infections among children in a slum community in Enderamulla(Sri Lanka Medical Association, 1999) Udayani, W.I.; Uduwevidane, K.; Uvais, A.L.; Wanniarachchi, S.L.; Warnakulasuriya, S.N.; de Silva, N.R.No Abstract availableItem Anthelmintics: a review of their comparative clinical pharmacology(Springer International, 1997) de Silva, N.; Guyatt, H.; Bundy, D.Virtually all the important helminth infections in humans can be treated with one of 5 anthelmintics currently in use: albendazole, mebendazole, diethylcarbamazine, ivermectin and praziquantel. These drugs are vital not only for the treatment of individual infections, but also useful in controlling transmission of the more common infections. This article reviews briefly the pharmacology of these 5 drugs, and then discusses current issues in the use of anthelmintics in the treatment and/or control of soil-transmitted nematode infections, filariasis, onchocerciasis, schistosomiasis (and other trematode infections), neurocysticercosis and hydatidosis. Mebendazole and albendazole are most effective against intestinal nematodes, but are contraindicated during the first trimester of pregnancy. The efficacy of prolonged therapy with these 2 drugs for treatment of larval cestode infections has not yet been established. Diethylcarbamazine is widely used to treat and control lymphatic filariasis, but adverse effects related to death of microfilariae or damage to adult worms may be marked. While ivermectin has been used in the treatment of patients with onchocerciasis, it is also undergoing investigation against lymphatic filariae. Praziquantel, used to treat schistosome infections, is also effective in other trematode infections and adult cestode infectionsItem Evaluation of effectiveness of iron-folate supplementation and anthelmintic therapy against aneamia in pregnancy - a study in the plantation sector of Sri Lanka(American Society of Clinical Nutrition, 1994) Athukorala, T.M.S.; de Silva, L.D.R.; Dechering, W.H.J.C.; Dissanayake, T.S.Intervention measures against anemia available to plantation workers during pregnancy include fortified food supplements (thriposha) and iron-folate supplements containing 60 mg elemental Fe. The effectiveness of these intervention measures was studied in 195 subjects whose iron and nutritional status were assessed at < 24 and > 32 wk of gestation. Taking thriposha conferred no significant benefit on maternal nutritional status, probably because sufficient amounts were not consumed. An increase in the duration of iron-folate supplementation to > 17 wk caused a significant positive change (P < 0.01) in hemoglobin, whereas an increase in the dose frequency had no significant benefit. Anthelminthic therapy in addition to iron-folate supplements caused a significant positive change in hemoglobin (P < 0.001) and serum ferritin (P < 0.005) compared with no supplementation. Thus, anthelminthic therapy significantly increased the beneficial effects of iron supplementation on hemoglobin concentration and iron status.Item Single dose treatment of mixed helminth infections--a comparison of three different regimes(Sri Lanka Medical Association, 1987) de Silva, D.G.H.; Lionel, N.D.; Premaratne, U.N.; Warnasuriya, N.; Soysa, P.E.; Fonseka, P.H.No abstract available