INTRODUCTIONWe reviewed the epidemiological features of rubella in Singapore and the impact of the national immunisation programme in raising the population herd immunity against rubella, with special reference to females in the reproductive age group, and in the elimination of congenital rubella syndrome (CRS).

MATERIALS AND METHODSEpidemiological data on all reported cases of rubella and CRS were obtained from the Communicable Diseases Division and Central Claims Processing System, respectively, at the Ministry of Health. Coverage of the childhood immunisation programme against rubella was based on the immunisation data maintained by the National Immunisation Registry, Health Promotion Board. To assess the herd immunity of the population against rubella, 4 serological surveys were conducted from 1989 to 1990, in 1993, 1998 and 2004.

RESULTSThe incidence of rubella has decreased significantly from the peak of 13.3 per 100,000 population in 1996 to 1.8 per 100,000 in 2007. CRS has virtually disappeared. With more than 92% to 93% of primary school leavers and preschool children annually vaccinated against rubella since 1976 and 1990, respectively, the level of susceptibility to rubella among women in the reproductive age group has gradually decreased from 44% in 1975 to 28% in 1985, and maintained at between 10% and 20% from 1987 to 1998. A considerable proportion (15.8%) of women 18 to 44 years of age remained susceptible to rubella infection in 2004.

CONCLUSIONRubella prevention and control has been successfully implemented. However, the relatively high level of susceptibility to rubella among women in the reproductive age group continues to be of concern. More public awareness and health educational efforts are needed and every opportunity should be taken to ensure that all susceptible women are identified and protected against the infection.

Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Humans ; Immunization ; utilization ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Population Surveillance ; Rubella Syndrome, Congenital ; epidemiology ; prevention & control ; Seroepidemiologic Studies ; Singapore ; epidemiology ; Young Adult

INTRODUCTIONWe carried out an epidemiological review of cholera in Singapore to determine its trends and the factors contributing to its occurrence.

MATERIALS AND METHODSEpidemiological data of all notified cases of cholera maintained by the Communicable Diseases Division, Ministry of Health, for the period 1992 to 2007 were collated and analysed. Case-control studies were carried out in outbreaks to determine the source of infection and mode of transmission. Linear patterns in age and ethnic distribution of cholera cases were assessed using chi2 test for trend.

RESULTSThere were a total of 210 cholera cases reported between 1992 and 2007. The incidence of cholera declined from 17 cases in 1992 to 7 cases in 2007. About a quarter of the cases were imported from endemic countries in the region. Between 76% and 95% of the reported cases were local residents. Four elderly patients with comorbidities and who sought medical treatment late died, giving a case-fatality rate of 1.9%. Vibrio cholerae 01, biotype El Tor, serotype Ogawa, accounted for 83.8% of the cases. The vehicles of transmission identified in outbreaks included raw fi sh, undercooked seafood and iced drinks cross-contaminated with raw seafood.

CONCLUSIONWith the high standard of environmental hygiene and sanitation, a comprehensive epidemiological surveillance system and licensing and control of food establishments, cholera could not gain a foothold in Singapore despite it being situated in an endemic region. However, health education of the public on the importance of personal and food hygiene is of paramount importance in preventing foodborne outbreaks. Physicians should also maintain a high level of suspicion of cholera in patients presenting with severe gastroenteritis, especially those with a recent travel history to endemic countries.

Adolescent ; Child ; Child, Preschool ; Cholera ; microbiology ; mortality ; Disease Outbreaks ; statistics & numerical data ; Female ; Foodborne Diseases ; epidemiology ; prevention & control ; Humans ; Incidence ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Population Surveillance ; Singapore ; epidemiology ; Vibrio cholerae O1 ; isolation & purification ; Young Adult

We describe the public health control measures implemented in Singapore to limit the spread of influenza A (H1N1-2009) and mitigate its social effects. We also discuss the key learning points from this experience. Singapore's public health control measures were broadly divided into 2 phases: containment and mitigation. Containment strategies included the triage of febrile patients at frontline healthcare settings, admission and isolation of confirmed cases, mandatory Quarantine Orders (QO) for close contacts, and temperature screening at border entry points. After sustained community transmission became established, containment shifted to mitigation. Hospitals only admitted H1N1-2009 cases based on clinical indications, not for isolation. Mild cases were managed in the community. Contact tracing and QOs tapered off, and border temperature screening ended. The 5 key lessons learnt were: (1) Be prepared, but retain flexibility in implementing control measures; (2) Surveillance, good scientific information and operational research can increase a system's ability to manage risk during a public health crisis; (3) Integrated systems-level responses are essential for a coherent public health response; (4) Effective handling of manpower surges requires creative strategies; and (5) Communication must be strategic, timely, concise and clear. Singapore's effective response to the H1N1-2009 pandemic, founded on experience in managing the 2003 SARS epidemic, was a whole-of-government approach towards pandemic preparedness planning. Documenting the measures taken and lessons learnt provides a learning opportunity for both doctors and policy makers, and can help fortify Singapore's ability to respond to future major disease outbreaks.
Communicable Disease Control ; organization & administration ; Contact Tracing ; Delivery of Health Care ; Disease Outbreaks ; prevention & control ; Focus Groups ; Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; prevention & control ; transmission ; Interviews as Topic ; Patient Isolation ; Public Health ; Singapore ; epidemiology ; Triage

OBJECTIVE: To assess the public health risk to Singapore posed by the Middle East respiratory syndrome (MERS) outbreak in the Republic of Korea in 2015. METHODS: The likelihood of importation of MERS cases and the magnitude of the public health impact in Singapore were assessed to determine overall risk. Literature on the epidemiology and contextual factors associated with MERS coronavirus infection was collected and reviewed. Connectivity between the Republic of Korea and Singapore was analysed. Public health measures implemented by the two countries were reviewed. RESULTS: The epidemiology of the 2015 MERS outbreak in the Republic of Korea remained similar to the MERS outbreaks in Saudi Arabia. In addition, strong infection control and response measures were effective in controlling the outbreak. In view of the air traffic between Singapore and MERS-affected areas, importation of MERS cases into Singapore is possible. Nonetheless, the risk of a serious public health impact to Singapore in the event of an imported case of MERS would be mitigated by its strong health-care system and established infection control practices. DISCUSSION: The MERS outbreak was sparked by an exported case from the Middle East, which remains a concern as the reservoir of infection (thought to be camels) continues to exist in the Middle East, and sporadic cases in the community and outbreaks in health-care settings continue to occur there. This risk assessment highlights the need for Singapore to stay vigilant and to continue enhancing core public health capacities to detect and respond to MERS coronavirus.

INTRODUCTIONWe reviewed the epidemiological features of 1348 hospitalised cases of influenza A (H1N1-2009) [pandemic H1N1] infection in Singapore reported between 15 July and 28 September 2009.

MATERIALS AND METHODSData on the demographic and epidemiological characteristics of hospitalised patients with confirmed pandemic H1N1 infection were collected from all restructured and private hospitals in Singapore using a standard template and were analysed retrospectively.

RESULTSOf the 1348 cases, 92 were classified as severely ill (i.e. were admitted to an intensive care unit and/or who died). Of these severely ill cases, 50 (54.3%) required mechanical ventilation. While overall hospitalisation rates were highest in the 0 to 11 months age group, the incidence of severely ill cases was highest in patients aged 65 years and older. Fifty per cent of all hospitalised cases and 28% of all severely ill cases did not have any underlying medical conditions. The following factors were found to be independently associated with a higher likelihood of severe illness: older age and the presence of the following comorbidities: neuromuscular disorders, epilepsy and obesity.

CONCLUSIONBetween 15 July and 28 September 2009, pandemic H1N1 infection caused significant illness requiring hospitalisation, as well as intensive care and mechanical ventilation in some cases. There were 18 deaths from pandemic H1N1 during this period, which corresponded to a case-fatality rate of 7 deaths for every 100,000 cases of pandemic H1N1.

Adolescent ; Adult ; Aged ; Child ; Child, Preschool ; Disease Outbreaks ; Epidemiologic Studies ; Female ; Hospitalization ; statistics & numerical data ; trends ; Humans ; Infant ; Infant, Newborn ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza, Human ; epidemiology ; Male ; Middle Aged ; Respiration, Artificial ; utilization ; Retrospective Studies ; Severity of Illness Index ; Singapore ; epidemiology ; Young Adult

INTRODUCTIONThe fi rst case of pandemic influenza A(H1N1) was detected in Singapore on 26 May 2009, 1 month after the fi rst cases of novel influenza A(H1N1) was reported in California and Texas in the United States. The World Health Organization declared the fi rst influenza pandemic of the 21st century on 11 June 2009.

MATERIALS AND METHODSConfirmed cases notified to the Ministry of Health between 27 May and 9 July 2009 were analysed. Various indicators of influenza activity were monitored throughout the study period. Estimates of the number of cases of H1N1-2009 were made using the number of polyclinic attendances for acute respiratory infection and influenza-like illness and the weekly prevalence of H1N1-2009.

RESULTSCases in Singapore affected mainly young adults, youths and children. By the end of September 2009, it was estimated that at least 270,000 persons had been infected by pandemic influenza A (H1N1) in Singapore. The peak number of cases occurred during E-week 30 (26 July-1 August) when an estimated 45,000 cases were seen in polyclinics and GP clinics. The hospitalisation, severe illness and mortality rates were estimated at 6 per 1000 cases, 0.3 per 1000 cases and 6.7 per 100,000 cases, respectively. The most common risk factors among hospitalised adult cases were asthma and diabetes. For hospitalised children, the most common risk factors were being under 5 years of age and asthma. The most common risk factors among persons with severe illness were diabetes in adults and epilepsy and being under 5 years of age in children. About half of cases with severe illness required mechanical ventilation. In addition, one-fifth of cases with severe illness had acute respiratory distress syndrome.

CONCLUSIONSThe fi rst wave of the influenza pandemic lasted about 10 weeks. Morbidity and mortality resulting from pandemic influenza were low.

Adolescent ; Adult ; Child ; Child, Preschool ; Comorbidity ; Disease Outbreaks ; Female ; Hospitalization ; Humans ; Infant ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza, Human ; diagnosis ; epidemiology ; mortality ; Male ; Middle Aged ; Risk Factors ; Singapore ; epidemiology ; Young Adult

INTRODUCTIONWe 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.

MATERIALS AND METHODSEpidemiological records of all reported enteric fevers maintained by the Communicable Diseases Division, Ministry of Health from 1990 to 2009 were analysed.

RESULTSA 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).

CONCLUSIONSingapore 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.

Adolescent ; Adult ; Child ; Child, Preschool ; Disease Outbreaks ; Epidemiologic Studies ; Female ; Humans ; Incidence ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Paratyphoid Fever ; epidemiology ; prevention & control ; Population Surveillance ; Singapore ; epidemiology ; Typhoid Fever ; epidemiology ; prevention & control ; Young Adult

INTRODUCTIONWe presented the findings from 2 seroprevalence studies conducted 6 years apart, so as to determine changes in the hepatitis B surface antigen (HBsAg) positivity rate and immunity to hepatitis B virus (HBV) among Singapore residents aged 18 to 69 years, and to assess the impact of a 4-year catch-up hepatitis B immunisation programme for adolescents and young adults launched in 2001.

MATERIALS AND METHODSTwo hepatitis B seroprevalence studies (HBSS) were conducted in 1999 and 2005 based on stored blood samples collected from 4698 participants aged 18 to 69 years during the national health survey (NHS) 1998 and from 3460 participants during the NHS 2004, respectively. Serology for HBsAg, hepatitis B e antigen (HBeAg) and antibody to HBsAg (anti-HBs) were tested by enzyme immunoassay in HBSS 1999 and electrochemiluminescence in HBSS 2005.

RESULTSThe overall age-standardised prevalence of HBsAg among Singapore residents aged 18 to 69 years decreased significantly from 4.0% in HBSS 1999 to 2.8% in HBSS 2005 (P = 0.002). The age-standardised prevalence of HBsAg in males (4.9% in 1999) and Chinese (4.7% in 1999) both decreased significantly to 2.7% and 2.8%, respectively in 2005. The overall age-standardised population immunity to HBV (anti-HBs >10 mIU/ml) increased from 39.7% in 1999 to 42.1% in 2005 (P = 0.019). In particular, the age-specific prevalence of anti-HBs showed a significant increase among those in the age group of 18 to 29 years from 27.9% in 1999 to 41.7% in 2005 (P <0.001) and among those in the age group of 30 to 39 years from 39.9% in 1999 to 44.7% in 2005 (P = 0.021).

CONCLUSIONThere was an overall decline in the HBsAg positivity rate as well as an overall increase in population immunity to HBV. Following the 4-year catch-up immunisation programme, there was a significant increase in the immunity to HBV infection in the younger population aged 18 to 29 years.

Adolescent ; Adult ; Age Factors ; Aged ; Biomedical Research ; Confidence Intervals ; Female ; Health Surveys ; Hepatitis B ; blood ; diagnosis ; epidemiology ; immunology ; Hepatitis B Surface Antigens ; immunology ; Hepatitis B Vaccines ; Humans ; Immunization Programs ; Immunoenzyme Techniques ; Male ; Middle Aged ; Population Surveillance ; Risk Factors ; Seroepidemiologic Studies ; Singapore ; epidemiology ; Young Adult

INTRODUCTIONWe undertook a study to evaluate the effectiveness of the National Childhood Immunisation Programme (NCIP) over the past 26 years by reviewing the epidemiological trends of the diseases protected, the immunisation coverage and the changing herd immunity of the population during the period of 1982 to 2007.

MATERIALS AND METHODSThe epidemiological data of all cases of diphtheria, pertussis, poliomyelitis, measles, mumps, rubella and acute hepatitis B notified to the Communicable Diseases Division, Ministry of Health (MOH) from 1982 to 2007 were collated and analysed. Data on tuberculosis (TB) cases were obtained from the TB Control Unit, Tan Tock Seng Hospital. Cases of neonatal tetanus and congenital rubella syndrome (CRS) among infants born in Singapore were identified from the Central Claims Processing System. The number of therapeutic abortions performed for rubella infections was retrieved from the national abortion registry. Coverage of the childhood immunisation programme was based on the immunisation data maintained by the National Immunisation Registry, Health Promotion Board. To assess the herd immunity of the population against the various vaccine-preventable diseases protected, the findings of several serological surveys conducted from 1982 to 2005 were reviewed.

RESULTSThe incidence of vaccine-preventable diseases covered under the NCIP had declined over the last 26 years with diphtheria, neonatal tetanus, poliomyelitis and congenital rubella virtually eliminated. The last case of childhood TB meningitis and the last case of acute hepatitis B in children below 15 years were reported in 2002 and 1996, respectively.

CONCLUSIONThe NCIP has been successfully implemented as evidenced by the disappearance of most childhood diseases, excellent immunisation coverage rate in infants, preschool and school children, and high level of herd immunity of the childhood population protected.

Adolescent ; Adult ; Child ; Child, Preschool ; Communicable Disease Control ; statistics & numerical data ; trends ; Communicable Diseases ; epidemiology ; Disease Notification ; statistics & numerical data ; Humans ; Immunity, Herd ; Immunization Programs ; statistics & numerical data ; Incidence ; Infant ; Population Surveillance ; Prevalence ; Singapore ; epidemiology

INTRODUCTIONSingapore's defense against imported novel influenza A (H1N1-2009) comprised public health measures in compliance with the World Health Organization's (WHO) International Health Regulations (IHR), 2005. We report herein on the epidemiology and control of the fi rst 350 cases notified between May and June 2009.

MATERIALS AND METHODSWe investigated the fi rst 350 laboratory-confirmed cases of novel influenza A (H1N1-2009) identified from the healthcare institutions between 27 May and 25 June 2009. Epidemiological details of these cases were retrieved and analysed. Contact tracing and active case finding were also instituted for each reported case, and relevant particulars including flight information were provided to WHO and overseas counterparts.

RESULTSThe fi rst 350 novel influenza A (H1N1-2009) cases comprised 221(63%) imported cases, 124 (35%) locally acquired cases and 5 (2%) cases with unknown source. The imported cases consisted of three waves involving the United States (US), Australia and Southeast Asia. In the fi rst wave, 11 (69%) of the 16 imported cases had visited the US within seven days prior to their onset of illness between 25 May and 4 June 2009. In the second wave, 20 (74%) of the 27 imported cases between 5 June and 12 June had travelled to Melbourne, Australia. In the third wave, 90 (51%) of the 178 imported cases between 13 June and 25 June were acquired from intra-regional travel in Southeast Asia. Specifically, 49 cases were from the Philippines and 40 (82%) of them had travelled to Manila. A total of 667 communications were effected through the IHR mechanism; a majority within 24 hours of disease notification.

CONCLUSIONSingapore experienced an unprecedented need for international cooperation in surveillance and response to this novel Influenza A (H1N1-2009) pandemic. The IHR mechanism served as a useful channel to engage in regional cooperation concerning disease surveillance and data sharing, but requires improvement.

Adolescent ; Adult ; Child ; Disease Notification ; Disease Outbreaks ; prevention & control ; Female ; Guideline Adherence ; Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human ; epidemiology ; prevention & control ; International Cooperation ; Male ; Singapore ; epidemiology ; Travel ; World Health Organization ; Young Adult