Aims: In Singapore, pneumococcal vaccination is recommended for the elderly (i.e. those ≥65 years of age) and people with chronic medical conditions. We investigated epidemiological characteristics associated with the uptake of pneumococcal vaccine based on a nationally representative cross-sectional sample of community-living adults aged ≥50 years. Methods: The data were obtained from the National Health Surveillance Survey (NHSS) 2013. Associations between pneumococcal vaccination and sociodemographic and health-related variables were analysed using univariable and multivariable logistic regression models. Results: Among 3672 respondents aged ≥50 years in the NHSS, 7.8% had taken the pneumococcal vaccination. A higher level of education and higher monthly household income were sociodemographic characteristics independently associated with pneumococcal vaccine uptake. Health-related characteristics predictive of pneumococcal vaccine uptake were better self-rated health and having a regular family doctor/general practitioner. Among those who responded to the two questions on vaccinations, 3.9% had been vaccinated against both seasonal influenza and pneumococcal infection, while 11.1% had taken only seasonal influenza vaccination in the past year. Conclusions: There is a need to boost pneumococcal vaccination coverage among community-dwelling older adults. These findings provide insights into reviewing and tailoring public-health strategies and programmes to increase vaccine uptake in at-risk population groups.
Abstract The yield of contact investigation on relapsed tuberculosis (TB) cases can guide strategies and resource allocation in the TB control programme. We conducted a retrospective cohort study to review the yield of contact investigation in relapsed TB cases and identify factors associated with TB infection (TBI) among close contacts of relapsed TB cases notified between 2018 and 2022 in Singapore. TB infection positivity was higher among contacts of relapsed cases which were culture-positive for Mycobacterium tuberculosis complex compared to those who were only polymerase chain reaction (PCR)-positive (14.8% vs. 12.3%). On multivariate analysis, after adjusting for age and gender of the index, gender, and existing comorbidities of contacts, factors independently associated with TBI were culture and smear positivity of the index (AOR 1.41, 95%CI 1.02–1.94), higher odds with every 10 years of increase in age compared to contacts below aged 30, contacts who were not Singapore residents (AOR 2.09, 95%CI 1.46–2.97), and household contacts (AOR 2.19, 95%CI 1.44–3.34). Although the yield of screening was higher for those who were culture-positive compared to only PCR-positive relapsed cases, contact tracing for only PCR-positive cases may still be important in a country with moderate TB incidence, should resources allow.
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.
The national strategy against pandemic influenza essentially consists of 3 prongs: (i) effective surveillance, (ii) mitigation of the pandemic’s impact, and (iii) render the population immune through vaccination. When the pandemic hits Singapore, the response plan aims to achieve the following 3 outcomes: (i) maintenance of essential services to limit social and economic disruption, (ii) reduction of morbidity and mortality through antiviral treatment, and (iii) slow and limit the spread of influenza to reduce the surge on healthcare services. The biggest challenge will come from managing the surge of demand on healthcare services. A high level of preparedness will help healthcare services better cope with the surge. Key words: Essential services, Healthcare, National preparedness, Non-pharmaceutical measures
An outbreak of gastroenteritis affected 453 attendees (attack rate 28·5%) of six separate events held at a hotel in Singapore. Active case detection, case-control studies, hygiene inspections and microbial analysis of food, environmental and stool samples were conducted to determine the aetiology of the outbreak and the modes of transmission. The only commonality was the food, crockery and cutlery provided and/or handled by the hotel's Chinese banquet kitchen. Stool specimens from 34 cases and 15 food handlers were positive for norovirus genogroup II. The putative index case was one of eight norovirus-positive food handlers who had worked while they were symptomatic. Several food samples and remnants tested positive for Escherichia coli or high faecal coliforms, aerobic plate counts and/or total coliforms, indicating poor food hygiene. This large common-source outbreak of norovirus gastroenteritis was caused by the consumption of contaminated food and/or contact with contaminated crockery or cutlery provided or handled by the hotel's Chinese banquet kitchen.
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 certification 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 first 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 certified poliomyelitis free along with the rest of the Western Pacific Region in 2000 after fulfilling all criteria for poliomyelitis eradication, including the establishment of a robust acute flaccid paralysis surveillance system. However, post-certification 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. Key words: Childhood immunisation, Herd immunity, Oral polio vaccine
The National Tuberculosis Programme (NTBP) monitors the occurrence and spread of tuberculosis (TB) and multidrug-resistant TB (MDR-TB) in Singapore. Since 2020, whole-genome sequencing (WGS) of Mycobacterium tuberculosis isolates has been performed at the National Public Health Laboratory (NPHL) for genomic surveillance, replacing spoligotyping and mycobacterial interspersed repetitive unit-variable number tandem repeats analysis (MIRU-VNTR). Four thousand three hundred and seven samples were sequenced from 2014 to January 2023, initially as research projects and later developed into a comprehensive public health surveillance programme. Currently, all newly diagnosed culture-positive cases of TB in Singapore are prospectively sent for WGS, which is used to perform lineage classification, predict drug resistance profiles and infer genetic relationships between TB isolates. This paper describes NPHL’s operational and technical experiences with implementing the WGS service in an urban TB-endemic setting, focusing on cluster detection and genomic drug susceptibility testing (DST). Cluster detection: WGS has been used to guide contact tracing by detecting clusters and discovering unknown transmission networks. Examples have been clusters in a daycare centre, housing apartment blocks and a horse-racing betting centre. Genomic DST: genomic DST prediction (gDST) identifies mutations in core genes known to be associated with TB drug resistance catalogued in the TBProfiler drug resistance mutation database. Mutations are reported with confidence scores according to a standardized approach referencing NPHL’s internal gDST confidence database, which is adapted from the World Health Organization (WHO) TB drug mutation catalogue. Phenotypic–genomic concordance was observed for the first-line drugs ranging from 2959/2998 (98.7 %) (ethambutol) to 2983/2996 (99.6 %) (rifampicin). Aspects of internal database management, reporting standards and caveats in results interpretation are discussed.
To the Editor: Over the past decade, the proportion of pulmonary multidrug-resistant tuberculosis (MDR TB) cases among Singapore-born patients remained low, whereas that among foreign-born patients was 10× higher (1,2). Since 2005, Singapore has experienced a sharp increase in the number of MDR TB cases from high-prevalence countries (3). We report local transmission of MDR TB in 2011, from a short-stay visitor to 2 Singapore-born persons in a correctional setting.
The index case-patient was a 34-year-old Burmese man (patient A) arrested 10 months after entering Singapore. A screening radiograph taken 2 days after arrest showed a right upper lobe cavitary lesion. The man was referred to the TB Control Unit. He had been coughing for 3 months but had no other concurrent conditions. When the abnormal radiograph results became known, the man was isolated within the prison. Sputum was collected, and first-line anti-TB drugs were administered pending sputum results. The sputum smear had 3+ acid-fast bacilli (AFB); mutations of the rpoB and katG genes were indicated by testing with GenoType MTDRplus (Hain Lifescience, Nehren, Germany). The patient’s treatment regimen was modified accordingly; appropriate second-line anti-TB treatment was started 14 days after he entered the institution. Mycobacterium tuberculosis complex (MTC) grew from sputum in 9 days; phenotypic drug-susceptibility testing (DST) demonstrated resistance to rifampin, isoniazid, streptomycin, and ethambutol and susceptibility to pyrazinamide, ethionamide, kanamycin, and ofloxacin.
One month after patient A was arrested, a Singapore-born man (patient B) in a public hospital received a diagnosis of HIV infection (67 CD4 cells/μL) and Pneumocystis jirovecii pneumonia. He was not an identified contact of patient A, although his job entailed accompanying prisoners from remand centers to justice courts. Antiretroviral treatment (ART) given 1 month after HIV diagnosis resulted in fever 7 days later. A repeat chest radiograph showed increased opacities in the left upper zone. Sputum smear was 4+ for AFB, and MTC with rpoB gene mutation was detected (Xpert MTB/RIF; Cepheid, Sunnyvale CA, USA). Second-line anti-TB drugs were administered. MTC was grown in sputum and blood in 14 and 32 days, respectively; phenotypic DST 8 weeks later showed a susceptibility profile that was identical (except for ethambutol susceptibility) to that of patient A.
Patient C was a 43-year-old Singapore-born man arrested 1 month after receiving an HIV diagnosis and beginning ART. He withheld his HIV status from prison authorities. He shared a cell with patient A for ≈48 hours at the remand center before the chest radiograph for patient A was taken. Patient C was released after 2 days and screened as a contact 2 months later; CD4 count was <20 cells/μL despite ART. Physical examination showed peripheral lymphadenopathy. T-SPOT.TB test (Oxford Immunotec Ltd., Abingdon, UK) result was negative, chest radiographs were unremarkable, and 2 sputum smears were negative for AFB (corresponding specimens for TB culture were negative). These findings were communicated to the patient’s primary physician. He was hospitalized 3 months later with fever and cough for 5 days but discharged himself, against medical advice, after 2 days. After 11 days, he was readmitted in septic shock to another hospital, at which time his sputum smear was positive for AFB and chest radiograph showed an increased right paratracheal stripe with right lower zone opacities. A bronchoesophageal fistula was also diagnosed, for which he declined intervention. Isoniazid, ethambutol, pyrazinamide, and rifabutin (his second-line ART regimen was incompatible with rifampin) were prescribed, and he discharged himself, against medical advice. After 5 days, he was readmitted with worsening cough; second-line anti-TB medications were instituted when his sputum specimen results were reported 8 weeks later as being phenotypically resistant to rifampin, isoniazid, and streptomycin. DST results for ethambutol were discrepant for isolates cultured from 2 sputum specimens and tested in 2 laboratories.
DNA genotyping by spoligotyping (Ocimum Biosolutions, Hyderabad, India) (4) showed that the isolates from all 3 patients belonged to type 467 H3, according to the SITVIT2 database (www.pasteur-guadeloupe.fr:8081/SITVITDemo/). Mycobacterial interspersed repetitive units–variable number tandem repeat genotyping with a 24-loci panel (Genoscreen, Lille, France) (5) similarly showed identical profiles (Figure). No other isolates in our database had matching profiles.
Figure
Spoligotype and 24-loci MIRU-VNTR typing results for Mycobacterium tuberculosis complex isolates recovered from 3 patients with multidrug-resistant tuberculosis (TB). Patient A (index case-patient), Burma-born man with TB, incarcerated in Singapore correctional ...
The cases reported here echo previous institutional outbreaks of MDR TB in industrialized countries (6–8). They are a reminder of the potentially devastating consequences when HIV and MDR TB intersect and the need for infection control measures where vulnerable and/or high-risk groups congregate. For patients A and B, rapid genotypic DST expedited the MDR TB diagnosis and institution of appropriate treatment and isolation measures and curtailed further spread. The unmasking immune reconstitution inflammatory syndrome that developed in patient B exemplifies the need for TB screening before starting ART in patients from countries with medium-to-high TB prevalence. For patient C, the several-week delay in instituting second-line TB medications could have been avoided had hospital medical teams been aware of his recent MDR TB exposure.
A recent update documented the highest rates of global MDR TB in 2009 and 2010 (9). Our experience reported here underscores the need to be constantly mindful of this infectious disease threat in our increasingly borderless world, even in countries where incidence of MDR TB is low.
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