Journal/Magazine Articles

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This collection contains original research articles, review articles and case reports published in local and international peer reviewed journals by the staff members of the Faculty of Medicine

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Author: search.filters.author.Chan, K.H.

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    Influenza virus infections among a sample of hospital attendees in Ragama, Sri Lanka
    (Sri Lanka Medical Association, 2010) Perera, K.V.H.K.K.; Chan, K.H.; Ma, E.; Peiris, J.S.M.
    OBJECTIVES: This study was carried out to define the types of influenza viruses circulating among humans and to understand the seasonality of influenza virus activity. Such information is essential for deciding on influenza vaccination strategy and on the appropriate time for delivering influenza vaccination, if such a vaccination policy was decided to be a priority. METHOD: During the period July 2003 - August 2004, 300 nasopharyngeal aspirates (NPA) were obtained from a systematic sample of patients reported to Out-patient Department, Colombo North Teaching Hospital, Ragama with ≤4 days history of acute respiratory tract infection (ARTI). The clinical signs and symptoms of the patients were prospectively recorded. Isolation of the influenza virus was carried out by inoculating in Madin Darby Canine Kidney cell line (MDCK). The isolates were identified by immunofluorescence assay and characterised by haemagglutination inhibition test. RT-PCR was carried out on all NPA samples. Genetic sequencing and phylogenetic analysis of the haemagglutinin gene of representative viruses were carried out. RESULTS: Twenty three influenza A and nine influenza B viruses were isolated by cell culture methods. Influenza A H3N2 Panama/2000/99-like viruses were isolated in 8% of patients with ARTI and influenza B/Sichuan/ 379/99-like viruses were isolated in 3%. Twenty eight influenza A virus infections were identified by the RT-PCR method. Phylogenetic analysis was carried out with data from other H3-subtype viruses isolated worldwide. The Sri Lanka viruses are antigenically and genetically similar to those in the northern and southern hemispheres. CONCLUSIONS: Influenza viruses circulate at different times of the year and is the aetiological agent causing 11% of all ARTI. Influenza activity corresponded to a peak in rainfall; however the correlation of influenza virus activity with rainfall is not invariable. The Sri Lankan isolates of 2003-4 were genetically related to the influenza A viruses circulating around the globe
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    Sensitive and inexpensive molecular test for falciparum malaria: detecting Plasmodium falciparum DNA directly from heat-treated blood by loop-mediated isothermal amplification
    (American Association For Clinical Chemistry, 2006) Poon, L.; Wong, B.W.; Ma, E.H.; Chan, K.H.; Chow, L.M.; Abeyewickreme, W.; Tangpukdee, N.; Yuen, K.Y.; Guan, Y.; Looareesuwan, S.; Peiris, J.S.
    BACKGROUND: Malaria is one of the most important parasitic infections in humans. A sensitive diagnostic test for malaria that could be applied at the community level could be useful in programs to control the disease. The aim of the present work was to develop a simple, inexpensive moleculartest for Plasmodium falciparum. METHODS: Blood was collected from controls (n = 100) and from patients diagnosed with falciparum malaria infection (n = 102), who were recruited to the study. Heat-treated blood samples were tested by a loop-mediated isothermal amplification (LAMP) assay for P. falciparum. Results were interpreted by a turbidity meter in real time or visually at the end of the assay. To evaluate the assay, DNA from these samples was purified and tested by PCR. Results from the LAMP and PCR assays were compared. RESULTS: The LAMP assay detected P. falciparum directly from heat-treated blood. The quantitative data from the assay correlated to the parasite counts obtained by blood-film microscopic analyses. When we used the PCR assay as the comparison method, the sensitivity and specificity of the LAMP assay were 95% and 99%, respectively. CONCLUSIONS: Unlike PCR, the LAMP assay does not require purified DNA for efficient DNA amplification, thereby reducing the cost and turnaround time for P. falciparum diagnosis. The assay requires only basic instruments, and assay positivity can be verified by visual inspection