Dengue Prevention and 35 Years of Vector Control in Singapore

A vector control program must be based on epidemiologic and entomologic data

Economics of neuraminidase inhibitor stock piling for pandemic influenza, Singapore.

We compared strategies for stock piling neuraminidase inhibitors to treat and prevent influenza in Singapore. Cost-benefit and cost-effectiveness analyses, with Monte Carlo simulations, were used to determine economic outcomes. A pandemic in a population of 4.2 million would result in an estimated 525-1,775 deaths, 10,700-38,600 hospitalization days, and economic costs of 0.7 dollars to 2.2 billion Singapore dollars. The treatment-only strategy had optimal economic benefits: stock piles of antiviral agents for 40% of the population would save an estimated 418 lives and 414 million dollars, at a cost of 52.6 million dollars per shelf-life cycle of the stock pile. Prophylaxis was economically beneficial in high-risk subpopulations, which account for 78% of deaths, and in pandemics in which the death rate was >0.6%. Prophylaxis for pandemics with a 5% case-fatality rate would save 50,000 lives and 81 billion dollars. These models can help policymakers weigh the options for pandemic planning

Epidemiology and Control of Legionellosis, Singapore

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

Health System for Dengue Control in Singapore

Dengue fever/dengue haemorrhagic fever (DF/DHF) first appeared in Singapore in an outbreak in 1960. In 1966, the Ministry of Health established the Vector Control Unit which was charged with the responsibility of controlling the dengue vector mosquitoes, Aedes aegypti and Aedes albopictus. The Unit immediately launched an Aedes control programme based on source reduction and public health education. To obtain reliable statistics on disease incidence, DF/DHF was made administratively notifiable in 1966, and finally, legally notifiable in 1977. It was also recognized early in the control programme that long-term and active participation by the community was essential for its implementation. A new legislation called the Destruction of Disease-Bearing Insects Act was thus enacted in 1968. The Act empowers vector control officers to enter and examine houses for mosquito breeding, to take appropriate control measures, and to serve offenders with orders and summonses which carry a fine or imprisonment by the court. With the new legislation in force, the Aedes control programme adopted an integrated approach of source reduction, public health education and law enforcement. When the new Ministry of the Environment was formed in 1972 to take over the responsibility of environmental health, its Vector Control and Research Department and the Quarantine & Epidemiology Department became responsible for the surveillance and control of DF/DHF in the country. Surveillance of disease incidence and Aedes vectors is important in the prevention and control of DF/DHF outbreaks. Disease surveillance is conducted by officers of the Quarantine & Epidemiology Department based on notifications on clinically diagnosed cases as well as on the number of blood specimens submitted by hospitals, clinics, and private practitioners to the Virology Division of the Department of Pathology in the Ministry of Health and the Department of Microbiology of the National University of Singapore for laboratory confirmation of dengue infection. Aedes surveillance depends on regular surveys of mosquito larvae and adults in designated DF/DHF-sensitive areas. In addition to destruction of breeding habitats, fogging is carried out when the Aedes house index is 2% and above, or when a potential outbreak situation arises such as the occurrence of a focus of two or more DF/DHF cases in an area

Epidemiology of Dengue in Singapore-Current Situation

There has been a resurgence of dengue fever/dengue haemorrhagic fever (DF/DHF) cases in Singapore in recent years. Following the large outreak in 1973 with 1,187 cases and 27 deaths, the incidence of DF/DHF declined with minor bi-annual outbreaks occurring in 1978, 1980 and 1982. Beginning from 1986, however, the DF/DHF situation changed for the worse when outbreaks of increasing size occurred almost annually. In the past 3 years, there were 1,733 cases in 1990, 2,179 cases in 1991 and 2,878 cases in 1992. In the 1991 and 1992 outbreaks, 93-95% of the notified cases required hospitalization and 92-95% of them were serologically confirmed by the IgM capture ELISA and/or the commercial Dengue Blot assay. The number of fatal cases, however, remained low with 3-6 reported deaths in the three outbreaks. All age groups were affected with the highest morbidity rate in children and young adults between 15 and 24 years of age. In contrast, in the earlier 1973 and 1978 outbreaks, more patients below the age of 15 years were observed. There was a slight predominance among males and Chinese had the highest morbidity rate compared with Malays and Indians. The recent outbreaks occurred mainly in highly populated urban and suburban areas in the eastern, northeastern and southeastern parts of the island. Patients living in landed property such as compound houses had a 9X higher morbidity rate than those living in high-rise flats. Cases were reported throughout the year and the number increased during May and June. The increased DF/DHF incidence was preceded by an increase in the Aedes mosquito population. In the 1991 and 1992 outbreaks, although the overall Aedes house index was<1 for both Ae aegypti and Ae albopictus higher indices were detected in localized areas with high dengue transmission. The proportion of compound houses found breeding Ae aegypti was 3-4 times and Ae albopictus 7-10 times higher than that of flats. The major breeding habitats were ornamental and domestic containers and discarded receptacles

Melioidosis in a Tropical City State, Singapore

The incidence of melioidosis in Singapore decreased during 1998–2007, with the exception of the first quarter of 2004. After heavy rainfalls, an increase in pneumonic cases with a high case-fatality rate was detected. We show that melioidosis has the potential to reemerge following adverse climate events

Influenza Excess Mortality from 1950–2000 in Tropical Singapore

10.1371/journal.pone.0008096PLoS ONE412

Epidemic Hand, Foot and Mouth Disease Caused by Human Enterovirus 71, Singapore

Singapore experienced a large epidemic of hand, foot and mouth disease (HFMD) in 2000. After reviewing HFMD notifications from doctors and child-care centers, we found that the incidence of HFMD rose in September and declined at the end of October. During this period, 3,790 cases were reported. We performed enteroviral cultures on 311 and 157 specimens from 175 HFMD patients and 107 non-HFMD patients, respectively; human enterovirus 71 (HEV71) was the most frequently isolated virus from both groups. Most of the HFMD patients were <4 years of age. Three HFMD and two non-HFMD patients died. Specimens from two HFMD and both non-HFMD patients were culture positive for HEV71; a third patient was possibly associated with the virus. Autopsies performed on all three HFMD and one of the non-HFMD case-patients showed encephalitis, interstitial pneumonitis, and myocarditis. A preparedness plan for severe HFMD outbreaks provided for the prompt, coordinated actions needed to control the epidemic

Genome-Wide Meta-Analysis of Five Asian Cohorts Identifies PDGFRA as a Susceptibility Locus for Corneal Astigmatism

Corneal astigmatism refers to refractive abnormalities and irregularities in the curvature of the cornea, and this interferes with light being accurately focused at a single point in the eye. This ametropic condition is highly prevalent, influences visual acuity, and is a highly heritable trait. There is currently a paucity of research in the genetic etiology of corneal astigmatism. Here we report the results from five genome-wide association studies of corneal astigmatism across three Asian populations, with an initial discovery set of 4,254 Chinese and Malay individuals consisting of 2,249 cases and 2,005 controls. Replication was obtained from three surveys comprising of 2,139 Indians, an additional 929 Chinese children, and an independent 397 Chinese family trios. Variants in PDGFRA on chromosome 4q12 (lead SNP: rs7677751, allelic odds ratio = 1.26 (95% CI: 1.16–1.36), Pmeta = 7.87×10−9) were identified to be significantly associated with corneal astigmatism, exhibiting consistent effect sizes across all five cohorts. This highlights the potential role of variants in PDGFRA in the genetic etiology of corneal astigmatism across diverse Asian populations