BACKGROUND: Simple methods have been developed to warn of pre-epidemics and epidemics in small areas using data of infectious diseases surveillance. Epidemic warnings are made if the index of cases per week per sentinel medical institution is greater than a defined value. A pre-epidemic warning means that an epidemic warning will be given in the following four weeks. While the methods are used routinely for surveillance in Japan, they remain to be validated. METHODS: Infectious diseases surveillance data of influenza-like illness and 12 pediatric diseases in the fiscal year between 1999 and 2001 were used in the analysis. We examined the frequency of warnings, temporal changes in the index before and after the onset of a warning, and the sensitivity, specificity, and positive predictive value of pre-epidemic warnings. RESULTS: For the majority of the diseases investigated, the proportion of weeks in which a warning was issued ranged between 0% and 10%. In several diseases including influenza-like illness, we observed a rapid increase and gradual decrease in the index before and after a warning. The sensitivity, specificity, and positive predictive value of a pre-epidemic warning were 90.4%, 93.7% and 23.9% for influenza-like illness, and ranged between 25.1-54.2%, 86.1-99.2%, and 2.5-20.8% for the pediatric diseases (chickenpox, rubella, measles, and mumps), respectively. CONCLUSIONS: The study showed that the methods used for determining whether or not to issue an epidemic warning were satisfactory in some diseases, including influenza-like illness, and may need to be improved in several other diseases.
BACKGROUND: There has been concern that variola virus might be held clandestinely elsewhere. Through constructing mathematical model based on the detailed epidemiologic data, we focused on simulating the various possible scenarios arising from a bioterrorist attack whereby smallpox virus was introduced into Japan, and sought to develop the most effective way of nationwide vaccination policy based on the theory of residual immunity. METHOD: The analysis is based on a deterministic mathematical model which predicted the epidemiologic outcome while simultaneously evaluating the effect of any specified control strategy of the smallpox epidemic. To clarify the required amount of vaccines, we performed mathematical analysis for hypothetical population to acquire herd immunity based on long-lasting vaccinal immunity. RESULTS: It is demonstrated that the crude size of the potential epidemic could be greatly affected by possible level of residual immunity. The results also suggest the possibility to develop optimal distribution of nationwide vaccination according to the immune status. The prevalence at 50th day among population without immunity in our simulation would be approximately 405 times greater than expected population with residual immunity, and required amount of vaccines for equal distribution would be 3.13 times more than optimal distribution. CONCLUSION: The mathematical model formulated could determine the vaccination priority based on the real status of immunity which required much less amount of vaccinations than would be calculated using an equal distribution program. It is therefore crucial to determine the real immunity status of the population via epidemiologic studies.
BACKGROUND: Coronary heart disease occurs nearly exponentially with age and differently between men and women. Therefore, difference in sex and age of family members yields errors in assessing the family history as a risk factor. The influence of sex and age on the positivity of family history was assessed numerically. METHODS: Through questionnaires filled in by the parents of 2316 high school students, information was obtained on the past history of coronary heart disease among students' parents, grandparents, uncles, and aunts. The sex- and age-specific proportion of a positive history was calculated from the past history among the 24, 071 family members. The influence of sex and age on a positive history was estimated as odds ratios by logistic regression analysis of the past history. RESULTS: The odds ratios obtained for sex and age difference were 1.61 (95% confidence interval: 1.42-1.83) and 1.07 (95% confidence interval: 1.06-1.07), respectively. This indicated that a positive history was 1.61 times higher among male members than among female members of the same age, and that a positive history increased by (1.07)y, where y was age difference by year. CONCLUSIONS: Potential errors resulting from disregarding the sex and age of family members can be substantial, judging from the above numerical figures. Some measures to control for the sex and age of family members are required in assessing family history of coronary heart disease.
BACKGROUND: Hypertension is an important risk factor of coronary heart disease. A new guidelines for hypertension prevention and management in The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure in the United States recommended lifestyle modification or medical treatment for subjects with prehypertension. However, whether prehypertension increases the risk of coronary atherosclerosis in the Japanese population is still unknown. METHODS: A cross-sectional study in a clinical setting was conducted. The subjects were 705 patients (417 males and 288 females) aged 30 years and older who underwent a first-time coronary angiography for suspected or known coronary heart disease at 5 major cardiology departments in the Fukuoka metropolitan area between September 1996 and August 1997. RESULTS: Compared to subjects with normal blood pressure, those with prehypertension had an increased risk of coronary atherosclerosis even after adjusting for other factors. CONCLUSION: Prehypertension may be an important clinical entity which requires treatment in the Japanese population.
BACKGROUND: Strategies for preventing premature cardiovascular disease include measures to control its risk factors. To plan such activities, prevalence of these factors must be known. Data regarding risk factor prevalence is limited in Bangladesh and measurement of biochemical factors is not always feasible. The aim of our study is to describe the non-biochemical risk factors in a clinic-based rural population of Bangladesh that would reflect at least a part of the problem in the rural area. METHODS: A cross sectional study was done in a clinic based patient population aged 20 years and older (471 males and 800 females) in a rural community of Bangladesh. A questionnaire on lifestyle including dietary and smoking habit was administered and physical examinations including height, weight, waist circumference, and blood pressure were measured in standardized way. RESULTS: Mean body mass index was 18.5 kg/m2 (standard deviation [SD]: 2.9 kg/m2) in males and 18.7 kg/m2 (SD: 3.3 kg/m2) in females. Mean systolic blood pressure was 120.0 mmHg (SD: 18.5 mmHg) and mean diastolic blood pressure 77.2 mmHg (SD: 9.9 mmHg) in all subjects. The prevalence of hypertension (140+/90+ mmHg and/or on treatment) was 17.8%. Prevalence of tobacco consumption (smoking and chewing) was 43.8% in males and 27.1 in females. Prevalence of abdominal obesity (waist circumference >94 cm in males, >80 cm in females) was 1.6 % and 11.4 % for males and females respectively. Proportion of overweight (BMI 25.0+) was 3.6%. CONCLUSION: Prevention programs and measures should be emphasized for the control of tobacco and hypertension in general, and central obesity in females, as far as rural population of Bangladesh is concerned.