Absence of Neisseria meningitidis W-135 Electrophoretic Type 37 during the Hajj, 2002

We document the absence of carriage of Neisseria meningitidis W-135 of the sequence type 11 in returning pilgrims after the Hajj 2002. This finding contrasts with the 15% carriage rate we previously reported in pilgrims returning from the Hajj 2001. The epidemiology of carriage may be changing or may have been controlled by vaccination and a policy of administering antibiotics to pilgrims from countries with a high incidence of meningococcal disease

Societal Learning in Epidemics: Intervention Effectiveness during the 2003 SARS Outbreak in Singapore

BACKGROUND: Rapid response to outbreaks of emerging infectious diseases is impeded by uncertain diagnoses and delayed communication. Understanding the effect of inefficient response is a potentially important contribution of epidemic theory. To develop this understanding we studied societal learning during emerging outbreaks wherein patient removal accelerates as information is gathered and disseminated. METHODS AND FINDINGS: We developed an extension of a standard outbreak model, the simple stochastic epidemic, which accounts for societal learning. We obtained expressions for the expected outbreak size and the distribution of epidemic duration. We found that rapid learning noticeably affects the final outbreak size even when learning exhibits diminishing returns (relaxation). As an example, we estimated the learning rate for the 2003 outbreak of severe acute respiratory syndrome (SARS) in Singapore. Evidence for relaxation during the first eight weeks of the outbreak was inconclusive. We estimated that if societal learning had occurred at half the actual rate, the expected final size of the outbreak would have reached nearly 800 cases, more than three times the observed number of infections. By contrast, the expected outbreak size for societal learning twice as effective was 116 cases. CONCLUSION: These results show that the rate of societal learning can greatly affect the final size of disease outbreaks, justifying investment in early warning systems and attentiveness to disease outbreak by both government authorities and the public. We submit that the burden of emerging infections, including the risk of a global pandemic, could be efficiently reduced by improving procedures for rapid detection of outbreaks, alerting public health officials, and aggressively educating the public at the start of an outbreak

Gender, ethnicity, health behaviour & self-rated health in Singapore

10.1186/1471-2458-7-184BMC Public Health718

Levels of cardiovascular disease risk factors in Singapore following a national intervention programme

OBJECTIVE: To evaluate the impact of the National Healthy Lifestyle Programme, a noncommunicable disease intervention programme for major cardiovascular disease risk factors in Singapore, implemented in 1992. METHODS: The evaluation was carried out in 1998 by the Singapore National Health Survey (NHS). The reference population was 2.2 million multiracial Singapore residents, 18--69 years of age. A population-based survey sample (n = 4723) was selected by disproportionate stratified and systematic sampling. Anthropometric and blood pressure measurements were carried out on all subjects and blood samples were taken for biochemical analysis. FINDINGS: The 1998 results suggest that the National Healthy Lifestyle Programme significantly decreased regular smoking and increased regular exercise over 1992 levels and stabilized the prevalence of obesity and diabetes mellitus. However, the prevalence of high total blood cholesterol and hypertension increased. Ethnic differences in the prevalence of diabetes mellitus, hypertension, and smoking; and in lipid profile and exercise levels were also observed. CONCLUSION: The intervention had mixed results after six years. Successful strategies have been continued and strengthened

(A) Basic S-E-I-R compartmental model of infectious disease, in which outbreak dynamics are represented by the number of individuals in four compartments corresponding to susceptible, exposed, infectious, and removed (or recovered) individuals.

<div><p>The rate at which individuals move from susceptible to exposed is according to mass-action dynamics with proportionality constant <i>α</i>.</p> <p>Individuals move from exposed to infectious at rate <i>η</i> and from infectious to removed at rate <i>γ</i>.</p> <p>(B) By assuming that the number of susceptible individuals is approximately constant (an appropriate approximation for outbreaks in which prevalence is never a large fraction of the total population) we introduce the new variable β = α<i>S</i> and reduce the four-compartment S-E-I-R model to a two-compartment model, designated here by the state variables <i>X</i> and <i>Y</i>. </p></div

Average daily removal rate of infectious individuals (γ) increased consistently for eight weeks following the initial outbreak of SARS in Singapore in 2003.

<div><p>Average infectious period obtained as <i>g</i> = 1/γ.</p> <p>Error bars are 95% confidence intervals calculated from the t-distribution given the mean and standard deviation of observed intervals between onset of clinical symptoms and removal.</p> <p>Confidence intervals are not provided for week 0, where only one case was observed (so zero degrees of freedom), or week 8, where the combination of high standard deviation in the observed interval (s.d.: 1.9) and few degrees of freedom (d.f.: 5) results in a nonsensical confidence interval that includes zero and negative values.</p></div