Browsing by Author "Chan, K.H."

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Incidence and phenotype of Inflammatory Bowel Disease from 2012-2013 across 9 countries in Asia: results from the 2012 access inception cohort
(American Gastroenterological Association(AGA) Institute, Published by Elsevier Inc., 2015) Ng, S.C.; Zeng, Z.; Chen, M.; Tang, W.; de Silva, H.J.; Niriella, M.A.; Senanayake, Y.U.; Yang, hong; Qian, J.M.; Yu, H.H.; Li, M.F.; Zhang, J.; Ng, K.K.; Ong, D.E.; Ling, K-L; Goh, K.L.; Hilmi, I.; Pisespongsa, P.; Aniwan, S.; Limsrivilai, J.; Manatsathit, S.; Abdullah, M.; Simadibrata, M.; Gunawan, J.A.; Chong, V.H.; Tsang, S.; Chan, K.H.; Lo, F.H.; Hui, A.J.; Chow, C.M.; Kamm, M.A.; Hu, P.; Ching, J.; Chan, F.K.L.; Sung, J.J.Y.
BACKGROUND: The incidence of inflammatory bowel disease (IBD) in Asia was first reported in the 2011 ACCESS inception cohort. This study aims to validate the incidence reported in 2011 by including a second independent cohort from 8 of the participating countries in 2011 and Brunei to investigate the incidence of IBD in Asia in 2012. METHODS: Incident IBD cases diagnosed between April 1, 2012 and March 31, 2013 from 18 centres, 11 cities and 9 countries in Asia were enrolled. Data including demographics and disease phenotype were entered into a Web-based database (http://www.access-apibd.com/access/index.html). Disease location and behavior were classified according to the Montreal classification. RESULTS: A total of 325 IBD patients were identified including 189 (58%) ulcerative colitis (UC), 119 (37%) Crohn’s disease (CD), and 17 (5%) indeterminate colitis (IC). The crude overall annual incidence per 100,000 of IBD was 1.61 (95% confidence interval, CI, 1.44-1.79) in 2012 compared with 1.15 (95% CI, 1.25-1.51) in 2011. The highest incidence in Asia was in Guangzhou (3.86 per 100,000), Hong Kong (2.91 per 100,000) followed by Macau (2.60 per 100,000). Overall ratio of UC to CD in 2012 was similar to that of 2011 (1.57 vs. 1.69; p=0.211). There were more male than female patients in both years (59% vs 60%; p=0.773). Mean age of diagnosis was 40 years (±15.96) in 2011 and 42 years (±16.30; p=0.084) in 2012. Median time from symptom onset to diagnosis was 6 months (IQR 3-24) and 7 months (IQR 2-16), respectively, in 2011 and 2012 (p=0.958). Disease behavior (B1: 72.0%, B2: 9.9%, B3: 4.4%, perianal: 13.2%), location for CD (L1: 25.3%, L2: 25.3%, L3: 49.5%) and UC (E1: 30.9%, E2: 40.1%, E3: 28.9%) did not differ from previous year. Most CD patients were non-smokers (80.3%) whereas 9.9% were current smokers and 9.9% were ex-smokers. CONCLUSION: The incidence of IBD, UC to CD ratio and age of disease onset in the ACCESS 2012 cohort was not significantly different from that reported in the 2011 cohort. Disease phenotype was also similar over 2 years. The ACCESS inception cohort reflects the true incidence of IBD in Asia.
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
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
Viral characteristics and genomics of early onset, single organ specific presentations in dengue
(Sri Lanka Medical Association, 2013) Premaratna, R.; Perera, H.K.K.; Chan, K.H.; Yeung, M.F.; Mettananda, C.; Peiris, J.S.M.; de Silva, H.J.
INTRODUCTION AND OBJECTIVES: Early onset neurological, hepatic and cardiac complications of dengue are increasingly recognized. However, doubts exist as to whether such complications of dengue are consequences of dengue shock syndrome rather than direct organ involvement. We studied virus characteristics and their genomics in patients who presented with early onset single organ involvement due to dengue, without features of DSS. METHODS: Blood samples were collected at admission of seven patients, who presented to the Professorial Medical Unit, Colombo North Teaching Hospital Ragama during 2011-2012, confirmed as having acute dengue by PCR. Samples were analysed with single-tube, nested RT-PCR using type-specific primers. Viral RNA was extracted and sequencing was performed. The dengue virus sequences were aligned with other sequences that are available in the GenBank and maximum-likelihood (ML) tree was made. RESULTS: Early onset organ specific manifestations included; self-limiting fits and clouding of consciousness on the 2nd day, rise in AST (1337iu/L) and ALT (749iu/L) on the 4th day and T wave inversions in the ECG on the 3rd day. Seven Dengue 1 viruses were isolated, which were in close homology in all 7 patients, based on the maximum likelihood tree with 1000 boot-straps. CONCLUSIONS: All the strains detected were clustered within the Genotype I clade of dengue-1 and in close homology with the dengue-1 viruses detected in the country in the recent past. The significance of viral characteristics and genomics related to organ specific manifestations need further study.