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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty

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    A Mixed infection of Plasmodium falciparum and Plasmodium malariae: the first report of a Plasmodium malariae infection after 37 years of its absence in Sri Lanka
    (2008) Hapuarachchi, H.A.C.; Abeysundara, S.; Gunawardena, N.K.; Manamperi, A.; Senevirathne, M. P.; Leemingsawat, S.; Chavalitshewinkoon-petmitr, P.; de Silva, N.R.; Abeyewickreme, W.
    Malaria has been endemic in Sti Lanka for several centuries. Currently, only Plasmodium falciparum and P. vivax are present in the country. P. malariae infections have not .been reported in Sri Lanka since 1969. The objective is to determine the presence of malaria species in a patient returned from Malawi. The clinical history of intermittent high fever for 2 weeks accompanied by severe headache, myalgia, arthralgia, vomitimg, loss of appetite and backache with ictetus and mild hepatosplenomegaly suggested malaria in this 51 year old patient. Apart from the basic biochemical investigations, presence of malarial species was determined by light microscopy and confirmed by Real-Time Polymerase Chain Reaction (PCR) technology. Biochemical investigations showed a high serum bilirubin (4.8 mg/di) and liver enzyme (SGOT = >125 units, SGPT = >250 units) levels. Serum haemoglobin level (12.8 g%) was normal. Except for the presence of ptoteinuria (albumin = ++), bile (+) and red blood corpuscles (RBC) in his urine, renal functions were normal. Microscopical examination of Giemsa stained thin and thick blood smears showed an asexual parasite density of 120,000 per ul of blood. Infected RBCs were not enlarged, The presence of double-chromatin and applique form trophozoites, occasionally invading multiple RBCs suggested P. falciparum infection. In addition, there were characteristic band form trophozoites of P. malariae. Real-Time PCR protocol confirmed the presence of both P. falciparum and P. malariae in this patient. This is the first case of P. malariae reported in Sri Lanka after 4 decades, though the infection had been acquired from Malawi. Clinical and biochemical evidence indicated liver dysfunction and a transient glomerulonephritis, both of which subsided after treatment with quinine. This case report emphasizes the need of physicians to be more vigilant about the presence of malaria among immigrants, despite the drastic reduction of malaria in the country in recent years. Hence, this report highlights the importance of a proper programme in Sri Lanka to screen immigrants for infectious diseases.
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    K76T point mutation of chloroquine resistance transporter gene: Is it a potential molecular marker for chloroquine resistance in Sri Lankan Plasmodium falciparum isolates?
    (Sri Lanka Association for the Advancement of Science, 2007) Hapuarachchi, H.A.C.; Dayanath, M.Y.D.; Abeysundara, S.; Manamperi, A.; Abeyewickreme, W.; de Silva, N.R.
    Current evidence suggests that K76T mutation of chloroquine resistance transporter (Pfcrt) gene may be used as a molecular marker for chloroquine (CQ) resistance of P. falciparum. This study was carried out to determine the frequency of K76T mutation of Pfcrt gene in Sri Lankan P. falciparum isolates collected from Mannar district in the Northern Province. Mutation patterns were compared with in vitro and in vivo CQ failure rates for this parasite population to analyze its association with resistance to CQ and to calculate the genotype-resistance (GRI) and genotype-failure (GFI) indices for K76T mutation. P. falciparum DNA was extracted from dried blood spots using a QiaAmp DNA Blood Mini Kit. Mutation patterns at 76 codon of Pfcrt of field isolates were detected using a polymerase chain reaction - restriction fragment length polymorphism assay. Parasite isolates were categorized into wild (sensitive) and mutant (resistant) types based on the banding patterns of digested products on 2% agarose gels. GRI and GFI indices were calculated for this parasite population. Of 38 CQ resistant isolates, 86.8% (N = 33) showed the mutant allele (K76T) at codon 76 of Pfcrt. There was a statistically significant association between the presence of K76T mutation and in vivo resistance to CQ (x2 = 5.11, p = 0.02). Of 33 sensitive isolates, 39.4% (N = 20) possessed the wild type allele at the same codon position. The calculated GRI and GFI indices were 1.13 and 1.38 respectively for this area. Even though results show a statistically significant association between the presence of K76T allele and CQ treatment failure of P. falciparum isolates in the study population, its mere presence alone does not seem to correlate with resistance to CQ. Therefore, mutations at other codons of Pfcrt shown to accompany K76T mutation as well as those in P. falciparum multi drug resistance 1 (Pfmdr1) gene need to be analyzed to determine whether other mutations play a role together with K76T in clinically resistant Sri Lankan parasite isolates. More studies are required to validate the calculated GRI and GFI values, which may be used to predict the therapeutic failure of CQ in a particular area in Sri Lanka in the future. Acknowledgement: National Science Foundation Research grant SIDA/2005/BT/03 and by the IAEA TC Project SRL 06/028
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    Night blood survey of a selected high-risk population for lymphatic filariasis
    (Sri Lanka Association for the Advancement of Science, 2007) Wijegunawardana, N.D.A.D.; Gunawardene, Y.I.N.S.; Abeyewickreme, W.; Gunawardena, N.K.; Hapuarachchi, H.A.C.; Abeysundara, S.
    Human infection with Wuchereria bancrofti causes a disabling parasitic disease known as lymphatic filariasis, which is a major public health and socio-economic problem in many parts of the world. Little is known about the prevalence of filariasis among high-risk populations for filariasis. Objective of this study was to determine such prevalence of lymphatic filariasis among Mahara prison inmates whom the Anti Filaria Campaign (AFC) has identified as a high-risk group. All inmates of Mahara Prison were screened for Microfilariae (Mf) except those in special cells, by night blood film microscopy to determine the prevalence of infection from February to May 2007. All inmates were males of greater than 15 years. Of the 423 inmates screened, 15 were positive for Mf, giving a Mf positive rate of 3.55% in the study population and a mean Mf density of 5 Mf/60 æl blood, ranging between 4 to 9.2 Mf /60 æl of blood with a standard deviation of 2.49. The highest number of infected inmates was residents of Colombo and Gampaha districts where transmission is currently taking place. This is one of the few studies undertaken to date to determine the prevalence of bancroftian filariasis among inmates of a prison, a neglected population in Sri Lanka. This study indicates that the Mf rate of bancroftian filariasis in this study population is far greater than the 0.18% currently reported in the country. Therefore, an intensive programme is recommended to contain the spread of infection within this study population. For this, a proper screening programme combined with antifilarial treatment and vector control programme is urgently required. Acknowledgements: Authors wish to acknowledge the financial assistance received from WHO/SEARO/TDR (grant no. SN 1152) and University of Kelaniya (Research grant no. RP/03/04/06/01/2006). Authors wish to thank Dr. Ravi Mudaliage, Senior Medical Officer, Prison's Hospital, Mahara, Ragama for his support and encouragement during field study activities. Authors also wish to thank Mr. M. Y. D. Dayanath, Ms. N.M. Ashoka Malanie, Mr. M.I.M.Peris, Mr. Y.L.Rassapana and other staff members of the Molecular Medicine Unit and Department of Parasitology, Faculty of Medicne, University of Kelaniya, Ragama for their assistance
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    Molecular markers of chloroquine resistance in Plasmodium falciparum in Sri Lanka:frequency before revision of the antimalarial drug policy
    (Academic Press, 2009) Hapuarachchi, H.A.C.; Abeysundara, S.; Dayanath, M.Y.D.; Manamperi, A.; Abeyewickreme, W.; de Silva, N.R.
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    Point mutations in the dihydrofolate reductase and dihydropteroate synthase genes of Plasmodium falciparum and resistance to sulfadoxine-pyrimethamine in Sri Lanka
    (American Society of Tropical Medicine and Hygiene, 2006) Hapuarachchi, H.A.C.; Dayanath, M.Y.D.; Bandara, K.B.A.T.; Abeysundara, S.; Abeyewickreme, W.; de Silva, N.R.; Hunt, S.Y.; Sibley, C.H.
    Sulfadoxine-pyrimethamine (SP) is the second-line treatment for Plasmodium falciparum malaria in Sri Lanka. Resistance to SP is caused by point mutations in the dihydrofolate reductase (Pf-dhfr) and dihydropteroate synthase (Pf-dhps) genes of P. falciparum. We determined the genotype of Pf-dhfr and Pf-dhps and the clinical response to SP in 30 field isolates of P. falciparum from Sri Lanka. All patients treated with SP had an adequate clinical response. Eighty-five percent (23 of 27) of pure field isolates carried parasites with double mutant alleles of Pf-dhfr (C59R + S108N) and showed about 200-fold higher levels of resistance to pyrimethamine than the wild type in a yeast system. None of the isolates had either known or novel mutations at other positions in the dhfr domain. In contrast, 67% (20 of 30) of the isolates carried parasites that were wild type for Pf-dhps. In Sri Lanka, detection of the triple mutant allele of Pf-dhfr will require tracking mutations at codon 51
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    Chloroquine resistant falciparum malaria among security forces personnel in the Northern Province of Sri Lanka
    (Sri Lanka Medical Association, 2004) Hapuarachchi, H.A.C.; Dayanath, M.Y.D.; Abeysundara, S.; Bandara, K.B.A.T.; Abeyewickreme, W.; de Silva, N.R.
    OBJECTIVE: To determine the occurrence and species distribution of malaria and the extent of chloroquine resistance among security forcespersonnel in a selected region of the Northern Province of Sri Lanka. DESIGN: A descriptive study. SETTING: Mannar District in the Northern Province. METHODS: Nine hundred and seventy five security personnel were screened for malaria by microscopy. Those who were positive were treated withchloroquine and were subjected to 28 day in vivo assay to determine chloroquine resistance. In vitro microtest assay was performed to determine the response of Plasmodium falciparum isolates to chloroquine in vitro. RESULTS: Of the 975 personnel screened, 181 (18.6%) were positive for malaria. P. falciparum was the predominant species (n = 125; 69.1%). The rest were due to P. vivax (n = 42; 23.2%) and mixed infections (n = 14; 7.7%). This was an inversion of the usual species distribution pattern in the country. In vivo assay revealed 38 (53.5%) P. falciparum infections as chloroquine resistant. Fifteen of 23 (65.2%) P. falciparum isolates showed evidence of resistance in vitro. None of the P. vivax infections showed evidence of chloroquine resistance. There was no significant difference in the severity of clinical disease between chloroquine resistant and sensitive infections at first presentation. Recrudescent P. falciparum infections had significantly lower mean parasite densities as well as lower clinical scores at recrudescence than at first presentation. CONCLUSION: Results demonstrate the high prevalence of malaria and chloroquine resistance in the study area and explains several contributory factors for this. There is an urgent need to review antimalarial drug policies in Sri Lanka
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