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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty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 Isothermal Diagnostic Assays for monitoring single nucleotide polymorphisms in Necator americanus associated with Benzimidazole drug resistance(Public Library of Science, 2016) Rashwan, N.; Bourguinat, C.; Keller, K.; Gunawardena, N.K.; de Silva, N.; Prichard, R.BACKGROUND: Soil-transmitted helminths (STHs) are the most prevalent intestinal helminths of humans, and a major cause of morbidity in tropical and subtropical countries. The benzimidazole (BZ) drugs albendazole (ABZ) and mebendazole (MBZ) are used for treatment of human STH infections and this use is increasing dramatically with massive drug donations. Frequent and prolonged use of these drugs could lead to the emergence of anthelmintic resistance as has occurred in nematodes of livestock. Previous molecular assays for putative resistance mutations have been based mainly on PCR amplification and sequencing. However, these techniques are complicated and time consuming and not suitable for resource-constrained situations. A simple, rapid and sensitive genotyping method is required to monitor for possible developing resistance to BZ drugs. METHODS: To address this problem, single nucleotide polymorphism (SNP) detection assays were developed based on the Smart amplification method (SmartAmp2) to target codons 167, 198, and 200 in the β-tubulin isotype 1 gene for the hookworm Necator americanus. FINDINGS: Diagnostic assays were developed and applied to analyze hookworm samples by both SmartAmp2 and conventional sequencing methods and the results showed high concordance. Additionally, fecal samples spiked with N. americanus larvae were assessed and the results showed that the Aac polymerase used has high tolerance to inhibitors in fecal samples. CONCLUSION: The N. americanus SmartAmp2 SNP detection assay is a new genotyping tool that is rapid, sensitive, highly specific and efficient with the potential to be used as a field tool for monitoring SNPs associated with BZ resistance. However, further validation on large numbers of field samples is required.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 Impact of mass chemotherapy for the control of filariasis on geohelminth infections in Sri Lanka(Academic Press, 2003) de Silva, N.R.; Pathmeswaran, A.; Fernando, S.D.; Weerasinghe, C.R.; Selvaratnam, R.R.; Padmasiri, E.A.; Montresor, A.No Abstract AvailableItem 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 The Treatment and control of helminth infections prevalent in Sri Lanka(The Kandy Society of Medicine, 1997) de Silva, N.R.; Guyatt, H.L.Item Clinical use of anthelmintics(1997) de Silva, N.; Guyatt, H.; Bundy, D.Item 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 Routine use of mebendazole in pregnancy(Sri Lanka Medical Association, 1996) de Silva, N.R.; Kodituwakku, K.K.A.P.; Edirisinghe, S.S.; de Silva, H.J.INTRODUCTION: The Ministry of Health has recommended the routine administration of a broad spectrum anthelmintic to all pregnant women after completion of the first trimester of pregnancy. OBJECTIVE: To estimate prevalence and intensity of geohelminth infections in pregnant women attending an antenatal clinic in Ragama and determine the use of anthelmintics by them. METHODS: Women on their first visit to antenatal clinics of the University Obstetrics Unit, General Hospital Colombo North, Ragama, during July-August 1995, were recruited for the study. Demographic details, duration of pregnancy and a history of using anthelmintics during the current pregnancy were noted. A stool sample was obtained and examined using modified Kato-Katz technique. RESULTS: 309 pregnant women were studied [mean age 26.6 years (SD 5.3)]. 94 (30.4%) had taken an anthelmintic during the current pregnancy. 78 (25.2%) had taken it in the second trimester, 9 (2.9%) in the third, 6 (1.8%) in the first, and one was uncertain of the timing. Stool samples were obtained from 181 women giving a compliance rate of 58.6%. Prevalence of geohelminth infections were: whipworm 10%, hookworm 2.2%, roundworm 1.1%. The intensities of the infections were mild. 157 (86.7%) did not have any geohelminth infection. Of the 181 women whose stools were examined, 52 had taken an anthelmintic. There was no significant difference in the prevalence of geohelminth infections between this group (6/52; 11.2%) and those who had not taken an anthelmintic (18/129; 13.9%) (Chi-square test). CONCLUSION: It may not be necessary to treat all pregnant women in Sri Lanka with anthelmintics, as some areas have a low prevalence of infection. Routine anthelmintic therapy could-be limited to areas where prevalence rates are known to be high.