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STUDY OBJECTIVES--To describe the prevalence of hepatitis B virus (HBV) infection in patients with sexually transmitted diseases (STD) and human immunodeficiency virus (HIV) infection, and to determine the role of sexual transmission of HBV infection in Singapore. DESIGN--A cross sectional study of all consecutive men presenting with a new episode of STD at a government outpatient clinic and all men with HIV infection on routine follow up at a government hospital. The prevalence of various HBV markers was compared with that of healthy males aged 15 years and above (controls). SETTING--Singapore, a city state of intermediate HBV endemicity. SUBJECTS--These comprised 497 STD patients, 47 HIV infected patients, and 418 controls. MAIN RESULTS--The overall seroprevalences of HBV infection in STD patients, HIV infected patients, and control subjects were 41.2%, 61.7%, and 33.3%, respectively (p < 0.001). The seroprevalences of hepatitis B surface antigen (6.2%, 8.5%, and 4.5%, respectively) were comparable in the three groups. Using stepwise logistic regression analysis, the adjusted seroprevalences of HBV infection in STD and HIV infected patients were respectively 2.4 times (95% confidence interval (CI), 1.7, 3.3) and 3.3 times (95% CI 1.7, 6.3) higher than in controls. HBV infection rates were higher among Chinese (odds ratio (OR), 1.9; 95% CI 1.6, 3.4) than non-Chinese, and among those aged 25-34 years (OR 2.4; 95% CI 1.6, 3.4), 35-44 years (OR 3.9; 95% CI 2.5, 5.9), and 45+ years (OR 6.2; 95% CI 3.8, 10.2) than in those aged 15-24 years. Sex related factors significantly associated with higher infection rates, independent of age and ethnic group, were reactive VDRL test (OR 2.4; 95% CI 1.2, 4.7), participation in anal intercourse (OR 2.3; 95% CI 1.2, 4.3), and having 10 or more lifetime sexual partners (OR 1.5; 95% CI, 1.0, 2.1). CONCLUSION--The importance of sexual transmission of HBV in an area of intermediate HBV endemicity was confirmed. Patients attending STD clinics should be routinely screened for HBV ...

Notified cases of dengue infections in Singapore reached historical highs in 2004 (9459 cases) and 2005 (13 817 cases) and the reason for such an increase is still to be established. We apply a mathematical model for dengue infection that takes into account the seasonal variation in incidence, characteristic of dengue fever, and which mimics the 2004–2005 epidemics in Singapore. We simulated a set of possible control strategies and confirmed the intuitive belief that killing adult mosquitoes is the most effective strategy to control an ongoing epidemic. On the other hand, the control of immature forms was very efficient in preventing the resurgence of dengue epidemics. Since the control of immature forms allows the reduction of adulticide, it seems that the best strategy is to combine both adulticide and larvicide control measures during an outbreak, followed by the maintenance of larvicide methods after the epidemic has subsided. In addition, the model showed that the mixed strategy of adulticide and larvicide methods introduced by the government seems to be very effective in reducing the number of cases in the first weeks after the start of control.

A voluntary immunization programme to prevent perinatal transmission of hepatitis B virus (HBV) infection in Singapore was implemented on 1 October 1985 as an integral component of the national childhood immunization programme. Up to April 1988, a total of 68,845 mothers who attended government maternal and child health clinics were screened for the disease. Of these, 2432 (3.5%) were positive for hepatitis B surface antigen (HBsAg) and 904 (1.3%) for hepatitis B e antigen (HBeAg). Virtually all the babies born to carrier mothers completed the full immunization schedule; and in addition, those of HBeAg-positive mothers were given a dose of hepatitis B immunoglobulin at birth. The hepatitis B immunization programme was extended on 1 September 1987 to cover all newborns. About 90% of the 15,943 babies delivered in government institutions from September 1987 to April 1988 were immunized at birth, with the subsequent doses being administered at maternal and child health clinics at 4-6 weeks and 5 months later. More than 85% of the children given the full course of plasma-derived and yeast-derived hepatitis B vaccine from birth continued to have protective antibody to HBV two years after immunization. The programme is being closely monitored to assess the duration of immunity and the need for booster doses, while seronegative adults are also being encouraged to be vaccinated.