Kee Tai Goh

Ministry of Health, Singapore, Tumasik, Singapore

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Publications (106)530.29 Total impact

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    ABSTRACT: Coxsackieviruses A6 (CV-A6) and A16 (CV-A16) and Enterovirus 71 (EV-A71) have caused periodic epidemics of hand, foot and mouth disease (HFMD) among children in Singapore. We conducted a cross-sectional study to estimate the seroprevalence of these enteroviruses among Singapore children and adolescents. The study was conducted between August 2008 and July 2010. It involved 700 Singapore residents aged 1-17 years whose residual sera were obtained following the completion of routine biochemical investigations in two public acute-care hospitals. The levels of neutralizing antibodies (NtAb) against CV-A6, CV-A16 and EV-A71 were analyzed by the microneutralization test. The age-specific geometric mean titer (GMT) of antibodies against each of the three enteroviruses and the 95% confidence intervals (CI) were calculated. The seroprevalence of CV-A6 and CV-A16 was high at 62.7% (95% CI: 59.1-66.2%) and 60.6% (95% CI: 56.9-64.1%), respectively. However, the seroprevalence of EV-A71 was significantly lower at 29.3% (95% CI: 26.0-32.8%). About 89.7% of the children and adolescents had been infected by at least one of the three enteroviruses by 13-17 years of age. About half (52.3%) were seropositive for two or all three enteroviruses, while only 16.1% had no NtAb against any of the three enteroviruses. High NtAb levels were observed in the younger age groups. CV-A6 and CV-A16 infections are very common among Singapore children and adolescents, while EV-A71 infections are less common. Infection is continually acquired from early childhood to adolescent age.
    PLoS ONE 05/2015; 10(5):e0127999. DOI:10.1371/journal.pone.0127999 · 3.53 Impact Factor
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    ABSTRACT: In line with regional and global goals for the elimination of rubella and congenital rubella syndrome (CRS), we reviewed the epidemiological situation in Singapore, based on surveillance reports on rubella and CRS, national immunization coverage and seroprevalence surveys. The aim of our review was to identify current gaps and steps taken to achieve the targets set by the World Health Organization (WHO) Western Pacific Regional Office (WPRO). Epidemiological data on clinical and laboratory-confirmed rubella cases, including CRS, notified to the Communicable Diseases Division, Ministry of Health, Singapore, from 2003 to 2013 were collated and analyzed. Vaccination coverage against rubella was obtained from the National Immunization Registry and School Health Services of the Health Promotion Board. The changing prevalence of rubella was determined from periodic serological surveys. The incidence of indigenous rubella cases per million population decreased from 37.2 in 2008 to 7.6 in 2013 and there had been no indigenous case of CRS in 2012 and 2013. Therapeutic abortions performed due to rubella infections had become uncommon. The annual measles, mumps, and rubella (MMR) vaccination coverage in childhood population remained high ranging from 93% to 96%. The overall susceptibility to rubella in women aged 18-44 years had reduced significantly from 15.8% in 2004 to 11.0% in 2010. The prevalence of IgG antibody against rubella among Singapore children aged 1-17 years was maintained at 87.3% in 2008-2010. All available data indicated that Singapore has made good progress towards the elimination of rubella and CRS. It has attained the targets set by the WHO WPRO for 2015. In preparation for verification of rubella elimination, an enhanced surveillance system has been implemented to ensure that all reported cases are laboratory confirmed, and genotyping of rubella virus strains isolated is carried out to provide evidence for interruption of endemic transmission. Copyright © 2015. Published by Elsevier Ltd.
    Vaccine 04/2015; 33(27). DOI:10.1016/j.vaccine.2015.04.003 · 3.49 Impact Factor
  • L W Ang, L James, K T Goh
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    ABSTRACT: In view of waning antitoxin titres over time after the last vaccine dose against diphtheria and tetanus, we determined the immunity levels in adults to identify most susceptible groups for protection in Singapore. Our study involved residual sera from 3293 adults aged 18-79 who had participated in a national health survey in 2010. IgG antibody levels were determined using commercial enzyme-linked immunosorbent assay. Overall, 92.0% (95% confidence interval [CI]: 91.1-92.9%) had at least basic protection against diphtheria (antibody levels ≥0.01 IU/ml), while 71.4% (95% CI: 69.8-72.9%) had at least short-term protection against tetanus (antibody levels >0.1 IU/ml). The seroprevalence declined significantly with age for both diseases; the drop was most marked in the 50- to 59-year age group for diphtheria and 60- to 69-year age group for tetanus. There was a significant difference in seroprevalence by residency for diphtheria (92.8% among Singapore citizens versus 87.1% among permanent residents; P = 0.001). The seroprevalence for tetanus was significantly higher among males (83.2%) than females (62.4%) (P < 0.0005). It may be of value to consider additional vaccination efforts to protect older adults at higher risk for exposure against diphtheria and tetanus, particularly those travelling to areas where diphtheria is endemic or epidemic. © The Author 2015. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
    Journal of Public Health 02/2015; DOI:10.1093/pubmed/fdv011 · 2.30 Impact Factor
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    ABSTRACT: We describe the epidemiological trends of measles in Singapore in relation to its progress towards measles elimination and identify gaps in fulfilling the World Health Organization Western Pacific Regional Office regional measles elimination criteria.Methods Epidemiological data on measles maintained by the Communicable Diseases Division, Ministry of Health from 1981 to 2012 were collated and analysed. Data on measles vaccination coverage were obtained from the National Immunization Registry and School Health Services, Health Promotion Board. To assess the seroprevalence of the population, the findings of periodic seroepidemiological surveys on measles were traced and reviewed.FindingsWith the successful implementation of the National Childhood Immunization Programme using the monovalent measles vaccine, measles incidence declined from 88.5 cases per 100,000 in 1984 to 6.9 per 100,000 in 1991. Resurgences were observed in 1992, 1993 and 1997. A ‘catch-up’ vaccination programme using the trivalent measles, mumps and rubella (MMR) vaccine was conducted in 1997, followed by introduction of the two-dose vaccination schedule in January 1998. Measles incidence subsequently declined sharply to 2.9 per 100,000 in 1998. Vaccination coverage was maintained at 95% for the first dose and 92–94% for the second dose. Seroprevalence surveys showed seropositivity for measles IgG antibodies in over 95% of adults in 2004, and in 83.1% of children aged 1–17 years in 2008–2010. Sporadic cases with occasional clusters of two or more cases continued to occur among the unvaccinated population, especially children aged below 4 years. The predominant measles virus genotype has shifted from D9 to the B3 and G3 genotypes, which are endemic in neighbouring countries.Conclusion Singapore has made good progress towards the elimination of endemic measles. To further eliminate sporadic cases of measles, the national immunisation schedule has recently been amended to vaccinate children with 2 doses of MMR vaccine before 2 years of age.
    Vaccine 11/2014; 32(51). DOI:10.1016/j.vaccine.2014.10.046 · 3.49 Impact Factor
  • L W Ang, J Cutter, L James, K T Goh
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    ABSTRACT: SUMMARY To assess the impact of past dengue epidemics in Singapore, we undertook a national seroepidemiological study to determine the prevalence of past dengue virus (DENV) infection in the adult population in 2010 and make comparisons with the seroprevalence in 2004. The study involved residual sera from 3293 adults aged 18-79 years who participated in a national health survey in 2010. The overall prevalence of anti-DENV IgG antibodies was 56·8% (95% confidence interval 55·1-58·5) in 2010. The seroprevalence increased significantly with age. Males had significantly higher seroprevalence than females (61·5% vs. 53·2%). Among the three major ethnic groups, Malays had the lowest seroprevalence (50·2%) compared to Chinese (57·0%) and Indians (62·0%). The age-standardized seroprevalence in adults was significantly lower in 2010 (54·4%) compared to 2004 (63·1%). Older age, male gender, Indian ethnicity, permanent residency and being home-bound were independent risk factors significantly associated with seropositivity. About 43% of the Singapore adult resident population remain susceptible to DENV infection as a result of the successful implementation of a comprehensive nationwide Aedes surveillance and control programme since the 1970s. Vector suppression and concerted efforts of all stakeholders in the community remain the key strategy in the prevention and control of dengue.
    Epidemiology and Infection 09/2014; 143(08):1-9. DOI:10.1017/S0950268814002507 · 2.49 Impact Factor
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    ABSTRACT: Weather factors are widely studied for their effects on indicating dengue incidence trends. However, these studies have been limited due to the complex epidemiology of dengue, which involves dynamic interplay of multiple factors such as herd immunity within a population, distinct serotypes of the virus, environmental factors and intervention programs. In this study, we investigate the impact of weather factors on dengue in Singapore, considering the disease epidemiology and profile of virus serotypes. A Poisson regression combined with Distributed Lag Non-linear Model (DLNM) was used to evaluate and compare the impact of weekly Absolute Humidity (AH) and other weather factors (mean temperature, minimum temperature, maximum temperature, rainfall, relative humidity and wind speed) on dengue incidence from 2001 to 2009. The same analysis was also performed on three sub-periods, defined by predominant circulating serotypes. The performance of DLNM regression models were then evaluated through the Akaike's Information Criterion. From the correlation and DLNM regression modeling analyses of the studied period, AH was found to be a better predictor for modeling dengue incidence than the other unique weather variables. Whilst mean temperature (MeanT) also showed significant correlation with dengue incidence, the relationship between AH or MeanT and dengue incidence, however, varied in the three sub-periods. Our results showed that AH had a more stable impact on dengue incidence than temperature when virological factors were taken into consideration. AH appeared to be the most consistent factor in modeling dengue incidence in Singapore. Considering the changes in dominant serotypes, the improvements in vector control programs and the inconsistent weather patterns observed in the sub-periods, the impact of weather on dengue is modulated by these other factors. Future studies on the impact of climate change on dengue need to take all the other contributing factors into consideration in order to make meaningful public policy recommendations.
    PLoS Neglected Tropical Diseases 05/2014; 8(5):e2805. DOI:10.1371/journal.pntd.0002805 · 4.49 Impact Factor
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    Noorul Fatha, Li Wei Ang, Kee Tai Goh
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    ABSTRACT: To understand the seroepidemiology of varicella zoster virus (VZV) in the Singaporean population, based on a paediatric survey conducted in 2008-2010 and the 2010 National Health Survey. The findings were compared with previous studies carried out in 1989-1990, 1993, 1998, and 2004. The paediatric survey involved 1200 subjects; residual diagnostic serum samples were collected from Singapore residents aged 1-17 years at two hospitals. The adult survey involved 3293 subjects; residual serum samples were obtained from Singapore residents aged 18-79 years who had participated in the 2010 National Health Survey. The seroprevalence in children under 5 years of age increased from 4% in 1989/1990 to 11.7% in 1998 and 33.2% in 2008-2010. For children aged 5-14 years, the corresponding seroprevalences were 22.8%, 59.5%, and 58.0%. The seroprevalence in children aged 5-14 years in 2008-2010 was not significantly different from that in 1998 (p=0.721). Among Singapore adults over 25 years of age, the seroprevalence remained consistently high at around 88% from 1998/1990 to 2010. Nearly two-thirds of pre-school children, 39.5% of primary school children, and 29% of adolescents aged 13-17 years are susceptible to VZV infection. At this level of immunity, it can be expected that outbreaks will continue to occur unless the varicella vaccine is introduced into the national childhood immunization programme.
    International journal of infectious diseases: IJID: official publication of the International Society for Infectious Diseases 11/2013; 22. DOI:10.1016/j.ijid.2013.10.003 · 2.33 Impact Factor
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    ABSTRACT: We undertook a national hepatitis B seroprevalence study to assess the seroprevalence of hepatitis B virus (HBV) markers in the adult population in Singapore in 2010 and make comparisons with the seroprevalence in 1998 and 2004. The study involved residual sera from national health surveys conducted every six years since 1998. The tests for HBV markers were carried out using commercial chemiluminescent microparticle immunoassay. In 2010, the prevalence of hepatitis B surface antigen (HBsAg) among 3293 Singapore residents aged 18-79 years was 3.6% (95% confidence interval [CI] 2.9-4.2%). Hepatitis B e antigen (HBeAg) was detected in 4.2% of those who were HBsAg positive. About 22.5% (95% CI 21.1-23.9%) were positive for antibody to hepatitis B core antigen (anti-HBc). The overall population immunity to HBV, as determined by antibody to hepatitis B surface antigen (anti-HBs)≥10mIU/mL, was 43.9% (95% CI 42.2-45.6%). Among young adults below 30 years of age, HBsAg prevalence (1.1%) was half that in 1998 and 2004, and in those positive for HBsAg, none was positive for HBeAg in 2010, compared to 20.8% in 1998 and 15.8% in 2004. In this age group, anti-HBc prevalence also decreased significantly from 22.1% in 2004 to 4.4% in 2010, while anti-HBs (≥10mIU/mL) prevalence increased significantly from 27.9% in 1998 to 43.3% in 2010 (p<0.001). The national childhood HBV immunisation and catch-up programmes implemented in 1987 and 2001-2004, respectively, had a significant impact in reducing HBV infection and in raising the immunity of the adult population 18-29 years of age.
    Vaccine 11/2013; 32(1). DOI:10.1016/j.vaccine.2013.10.057 · 3.49 Impact Factor
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    ABSTRACT: We investigated an outbreak of 47 probable and 6 confirmed cases of microsporidial keratoconjunctivitis involving participants of an international rugby tournament in Singapore in April 2012.The mode of transmission was eye contact with soil. Vittaforma corneae was identified in 4 of 6 corneal scrapings and in 1 of 12 soil water samples.
    Emerging Infectious Diseases 09/2013; 19(9):1484-6. DOI:10.3201/eid1909,121464 · 7.33 Impact Factor
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    ABSTRACT: We undertook a national paediatric seroprevalence survey of measles, mumps and rubella (MMR) in Singapore to assess the impact of the national childhood immunization programme against these three diseases after introduction of the trivalent MMR vaccine in 1990. The survey involved 1200 residual sera of Singapore residents aged 1–17 years collected from two hospitals between 2008 and 2010. The overall prevalence of antibodies against measles, mumps and rubella was 83·1% [95% confidence interval (CI) 80·9–85·1], 71·8% (95% CI 69·1–74·2) and 88·5% (95% CI 86·6–90·2), respectively. For all three diseases, the lowest prevalence was in children aged 1 year (47·8–62·3%). The seroprevalence of the vaccinated children declined over time. The national MMR immunization programme is effective in raising the herd immunity of the childhood population, although certain age groups are more susceptible to infection, in particular, those who are not eligible for vaccination at age <15 months.
    Epidemiology and Infection 08/2013; 141(08). DOI:10.1017/S0950268812002130 · 2.49 Impact Factor
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    ABSTRACT: A national pediatric survey was undertaken to determine the prevalence of hepatitis B virus markers in Singapore. The aim was to assess the impact of the national childhood immunization program against hepatitis B implemented for all newborns since 1987. The survey involved prospective collection of residual sera from Singapore residents aged 1-17 years attending inpatient services or day surgery in two public hospitals between August 2008 and July 2010. A total of 1,200 sera were collected comprising 400 in each of the three age groups of 1-6, 7-12, and 13-17 years. The sera were tested for hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs). Four of the 1,200 samples tested positive for HBsAg, giving an overall prevalence of 0.3%. One and three in the 7-12 years and 13-17 years age groups, respectively, were positive for HBsAg. About 40% possessed anti-HBs (≥10 mIU/ml); the antibody prevalence decreased significantly from 63.8% in children aged 1-6 years to 32.8% in 7-12 year olds, and 23.5% in 13-17 year olds (P < 0.0005). The successful implementation of the national childhood hepatitis B immunization program over the last two decades has resulted in a low prevalence of HBsAg among children and adolescents. Singapore has achieved the World Health Organization Western Pacific Region's goal in reducing the prevalence of chronic HBV infection to below 2% among children aged 5 years and older by 2012 and to below 1% by 2017. J. Med. Virol. 85:583-588, 2013. © 2013 Wiley Periodicals, Inc.
    Journal of Medical Virology 04/2013; 85(4):583-8. DOI:10.1002/jmv.23496 · 2.22 Impact Factor
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    ABSTRACT: OBJECTIVES: We undertook an epidemiological review to determine the trend and characteristics of acute hepatitis E in Singapore over the last 12 years. METHODS: We analysed the epidemiological records of all laboratory-confirmed cases of acute hepatitis E maintained at the Communicable Diseases Division, Ministry of Health, from 2000 to 2011. RESULTS: A total of 540 laboratory-confirmed cases of acute hepatitis E was reported with more than half imported, mainly from India and Bangladesh. Among the indigenous cases, the mean annual incidence per 100,000 population increased from 0.05 in 2000-2002 to 0.92 in 2009-2011. There was a male predominance and the median age was 46 years. Among the 3 major ethnic groups of Singapore residents, Chinese and Indians had higher mean annual incidence rate compared to Malays. All the indigenous cases occurred singly and sporadically and could not be epidemiologically linked to one another by person, place or time. No common food item was implicated. CONCLUSIONS: Indigenous acute hepatitis E has emerged as a major cause of acute viral hepatitis in Singapore. While epidemiological investigations are ongoing to elucidate the risk factors and modes of transmission, travellers should be reminded to practise a high standard of personal and food hygiene when visiting endemic countries.
    The Journal of infection 12/2012; DOI:10.1016/j.jinf.2012.11.015 · 4.02 Impact Factor
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    ABSTRACT: Introduction: This study reviewed the epidemiological trends of poliomyelitis from 1946 to 2010, and the impact of the national immunisation programme in raising the population herd immunity against poliovirus. We also traced the efforts Singapore has made to achieve certifi cation of poliomyelitis eradication by the World Health Organisation. Materials and Methods: Epidemiological data on all reported cases of poliomyelitis were obtained from the Communicable Diseases Division of the Ministry of Health as well as historical records. Coverage of the childhood immunisation programme against poliomyelitis was based on the immunisation data maintained by the National Immunisation Registry, Health Promotion Board. To assess the herd immunity of the population against poliovirus, 6 serological surveys were conducted in 1962, 1978, 1982 to 1984, 1989, 1993 and from 2008 to 2010. Results: Singapore was among the fi rst countries in the world to introduce live oral poliovirus vaccine (OPV) on a mass scale in 1958. With the comprehensive coverage of the national childhood immunisation programme, the incidence of paralytic poliomyelitis declined from 74 cases in 1963 to 5 cases from 1971 to 1973. The immunisation coverage for infants, preschool and primary school children has been maintained at 92% to 97% over the past decade. No indigenous poliomyelitis case had been reported since 1978 and all cases reported subsequently were imported. Conclusion: Singapore was certifi ed poliomyelitis free along with the rest of the Western Pacifi c Region in 2000 after fulfi lling all criteria for poliomyelitis eradication, including the establishment of a robust acute fl accid paralysis surveillance system. However, post-certifi cation challenges remain, with the risk of wild poliovirus importation. Furthermore, it is timely to consider the replacement of OPV with the inactivated poliovirus vaccine in Singapore's national immunisation programme given the risk of vaccine-associated paralytic poliomyelitis and circulating vaccine-derived polioviruses.
    Annals of the Academy of Medicine, Singapore 11/2012; 41(11):518-28. · 1.22 Impact Factor
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    ABSTRACT: The delay in HIV diagnosis has been identified as a significant reason for late presentation to medical care. This research aims to elucidate the significant determinants of late-stage HIV infection in Singapore between 1996 and 2009, after the advent of highly active anti-retroviral therapies. We included 3735 patients infected via sexual mode of transmission from the National HIV Registry diagnosed between 1996 and 2009. Late-stage HIV infection is defined as CD4 count less than 200 mm(3) or AIDS-defining opportunistic infections at fi rst diagnosis or within one year of HIV diagnosis. We determined independent epidemiological risk factors for late-stage HIV infection at first diagnosis using multivariate logistic regression. Multivariate analysis showed that older age corresponded significantly with increasing odds of late-stage HIV infection. Compared to persons diagnosed at 15 to 24 years of age, those diagnosed at age 55 years and above were associated with 5-fold increased likelihood of late-stage infection (adjusted odds ratio (AOR): 5.17; 95% CI, 3.21 to 8.33). Chinese ethnicity, singlehood, and non-professional occupations were also significantly associated with late-stage HIV infection. Persons detected in the course of medical care had over 3.5 times the odds of late-stage infection (AOR: 3.55; 95% CI, 2.71 to 4.65). Heterosexual mode of transmission and having sex workers and social escorts as sexual partners, were the other epidemiological risk factors with significant associations. The findings of this study emphasises the need to increase HIV awareness and to encourage early and regular HIV testing among at-risk persons.
    Annals of the Academy of Medicine, Singapore 05/2012; 41(5):194-9. · 1.22 Impact Factor
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    ABSTRACT: Singapore has experienced remarkable socioeconomic progress over the last few decades, with a corresponding rise in standards of sanitation and living conditions. We undertook a study to describe its epidemiological trends of hepatitis A over the last 2 decades. We analysed the epidemiological data on all laboratory-confirmed cases of hepatitis A from 1990 to 2009. We also described 3 outbreaks which occurred in 1991, 1992 and 2002. To determine the changing prevalence of hepatitis A virus (HAV) infection, we compared the findings from a seroepidemiological study conducted in 1993 with earlier surveys in 1975 and 1984/1985. The incidence of indigenous hepatitis A cases per 100,000 population declined significantly from 1.8 in 1989 to 0.7 in 2009, and more than half were imported. While majority of the imported cases were Singapore residents, the proportion of imported cases among Singapore residents had decreased significantly. Most of the Singapore residents contracted the disease from Southeast Asia and the Indian subcontinent. The overall prevalence of HAV infection in the population declined from 31.8% in 1984/85 to 25.9% in 1993. The incidence and seroprevalence of hepatitis A in Singapore are comparable to other developed countries. As Singapore is situated in a region highly endemic for HAV, it is very vulnerable to the introduction of the disease because of the high volume of regional travel and import of food, especially shellfish. While we note that there have been no further shellfish-associated outbreaks since 2002, sustained vigilance, strict control of food import by the authorities and public health education on the risk of consuming shellfish, especially cockles, raw and half-cooked, should be maintained.
    Annals of the Academy of Medicine, Singapore 10/2011; 40(10):439-47. · 1.22 Impact Factor
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    ABSTRACT: To determine trends and clinical and epidemiologic features of legionellosis in Singapore, we studied cases reported during 2000-2009. During this period, 238 indigenous and 33 imported cases of legionellosis were reported. Cases were reported individually and sporadically throughout each year. Although the annual incidence of indigenous cases had decreased from 0.46 cases per 100,000 population in 2003 to 0.16 cases per 100,000 in 2009, the proportion of imported cases increased correspondingly from 6.2% during 2000-2004 to 27.3% during 2005-2009 (p<0.0005). The prevalence of Legionella bacteria in cooling towers and water fountains was stable (range 12.1%-15.3%) during 2004-August 2008.
    Emerging Infectious Diseases 07/2011; 17(7):1209-15. DOI:10.3201/eid1707.101509 · 7.33 Impact Factor
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    ABSTRACT: We investigated the epidemiological features of the 2007 dengue outbreak to determine the factors that could have triggered it two years after the previous large outbreak in 2005. All laboratory-confirmed cases of dengue reported during the year, as well as entomological and virological data, were analysed. A total of 8826 cases including 24 deaths were reported in 2007, giving an incidence of 192.3 cases per 100 000 residents and a case-fatality rate of 0.27%. The median age of the cases was 37 years (interquartile range 25 to 50), with an age range from two days to 101 years, which was higher than the median age of 31 years (interquartile range 20 to 42), with a range from four days to 98 years, in 2005. The overall Aedes premises index in 2007 was 0.68%, lower than the 1.15% observed in 2005. The predominant dengue serotype in 2007 was dengue virus DENV-2 which re-emerged with a clade replacement in early 2007, and overtook the predominant serotype (DENV-1) of 2005. Seroprevalence studies conducted in the three largest outbreak clusters revealed that 73.2% of residents with recent infection were asymptomatic. With the exception of an increase in the median age of the cases, and a change in the predominant dengue serotype, the epidemiological features of the 2007 epidemic were largely similar to those of 2005. Singapore remains vulnerable to major outbreaks of dengue, despite sustained vector control measures to maintain a consistently low Aedes premises index.
    04/2011; 2(2):24-9. DOI:10.5365/WPSAR.2010.1.1.011
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    ABSTRACT: This paper describes the epidemiological, microbiological and environmental investigations conducted during an outbreak of Salmonella gastroenteritis in Singapore. A case-control study was undertaken to identify the vehicle of transmission. Microbiological testing was performed on faecal, food and environmental samples. Isolates of Salmonella were further characterized by phage typing and ribotyping. There were 216 gastroenteritis cases reported from 20 November to 4 December 2007. The causative agent was identified as Salmonella enterica subspecies enterica serotype Enteritidis for 14 out of 20 cases tested. The vehicle of transmission was traced to cream cakes produced by a bakery and sold at its retail outlets (P < 0.001, OR = 143.00, 95% Cl = 27.23-759.10). More than two-thirds of the 40 Salmonella strains isolated from hospitalized cases, food samples and asymptomatic food handlers were of phage type 1; the others reacted but did not conform to any phage type. The phage types correlated well with their unique antibiograms. The ribotype patterns of 22 selected isolates tested were highly similar, indicating genetic relatedness. The dendrogram of the strains from the outbreak showed distinct clustering and correlation compared to the non-outbreak strains, confirming a common source of infection. The cream cakes were likely contaminated by one of the ingredients used in the icing. Cross-contamination down the production line and subsequent storage of cakes at ambient temperatures for a prolonged period before consumption could have contributed to the outbreak.
    03/2011; 2(1):23-30. DOI:10.5365/WPSAR.2010.1.1.001
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    ABSTRACT: An epidemiological survey was conducted in 1990-91 to determine the personal and environmental factors in Singapore which may affect blood lead levels. A total of 1,408 children and adults aged from 6 months to over 50 years were interviewed and their blood samples obtained for analysis using atomic absorption spectroscopy. Overall, the geometric mean blood lead level of the population surveyed was 76.6 micrograms/l. Multivariate analyses revealed that significant variations in blood lead concentrations were related, in decreasing order of importance, to: sex, age, active and passive smoking, exposure to traffic, and exposure to recent paintwork. The consumption of alcohol and traditional medicines were found not to be significant determinants. To reduce the environmental lead problem in Singapore, unleaded petrol has been introduced and control of lead additive in paints is being considered. The national anti-smoking programme should further contribute to an overall reduction in the blood lead level of the population.
    Reviews on environmental health 01/2011; 9(4):207-13. DOI:10.1515/REVEH.1991.9.4.207
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    ABSTRACT: We studied the epidemiological trends of enteric fevers (typhoid and paratyphoid fever) in Singapore from 1990 to 2009 and carried out a review of the current prevention and control measures. Epidemiological records of all reported enteric fevers maintained by the Communicable Diseases Division, Ministry of Health from 1990 to 2009 were analysed. A total of 2464 laboratory confirmed cases of enteric fevers (1699 cases of typhoid and 765 cases of paratyphoid) were reported. Of these, 75% were imported, mainly from India and Indonesia. There had been a significant fall in the mean annual incidence rate of indigenous enteric fevers from 4.3 per 100,000 population in 1990 to 0.26 per 100,000 population in 2009 (P <0.005) with a corresponding increase in the proportion of imported cases from 71% between 1990 and 1993 to 92% between 2006 and 2009 (P <0.0005). Imported cases involving foreign contract workers increased significantly from 12.8% between 1990 and 1993 to 40.4% between 2006 and 2009 (P <0.0005). Singapore has experienced a marked decline in the incidence of enteric fevers that is now comparable to that of other developed countries. Continued vigilance and proactive measures that address the changing epidemiology of enteric fevers in Singapore are necessary to sustain the milestone achieved in the past 2 decades.
    Annals of the Academy of Medicine, Singapore 12/2010; 39(12):889-8. · 1.22 Impact Factor

Publication Stats

2k Citations
530.29 Total Impact Points

Institutions

  • 2003–2014
    • Ministry of Health, Singapore
      Tumasik, Singapore
    • National Environment Agency, Singapore
      Tumasik, Singapore
  • 1994–2013
    • National University of Singapore
      • Centre for Molecular Epidemiology
      Tumasik, Singapore
  • 2003–2008
    • Tan Tock Seng Hospital
      • Department of Infectious Diseases
      Singapore, Singapore
  • 1993–2000
    • Singapore General Hospital
      • Department of Clinical Research
      Tumasik, Singapore