Modelling and predicting the effect of temperature, water activity and pH on growth of Streptococcus iniae in Tilapia.

AIMS: To evaluate and model the growth of Streptococcus iniae affect by temperatures (10-45 degrees C), water activity (A(w); 0.995-0.957), and pH (5-8). METHODS AND RESULTS: Temperatures, A(w), and pH were adjusted. The behaviour of S. iniae was studied and modelled. Growth curves were fitted by using logistic, Gompertz, and Baranyi models. The maximum growth rates obtained from the primary model were then modelled as a function of temperature, A(w), and pH using the Belehradek-type models for secondary model. The optimum values for growth were found to be in the range of 35-40 degrees C, A(w) 0.995-1, and pH 6-7. The statistical characteristics of the models were validated by r(2), mean square error, bias, and accuracy factors. The results of validation indicated that Baranyi model performed the best. CONCLUSIONS: The effect of temperature, A(w)/NaCl, pH control of S. iniae in tilapia could be satisfactorily predicted under current experimental conditions, and the proposed models could serve as a tool for this purpose. SIGNIFICANCE AND IMPACT OF THE STUDY: The suggested predictive model can be used for risk assessment concerning S. iniae in tilapia.

Disaster epidemiology and medical response in the Chi-Chi earthquake in Taiwan.

STUDY OBJECTIVE: We examine the mortality and morbidity associated with earthquakes in the Chi-Chi earthquake in Taiwan in 1999. METHODS: Crude casualty data were collected from the reports of the government, local health bureaus, and 97 hospitals. The demographic data from the annual report of the Department of Interior were also employed for data analysis. Cross tables showing incidence of deaths and injuries by age, sex, time, and geographic distribution were generated to compare the mortality among different subgroups. Multiple regression models were established to explore the risk factors related to the mortality caused by earthquakes. RESULTS: The following results were found: the mortality rate increased with proximity to the epicenter, mortality was higher among the elderly than among young people, 30% of the victims died from head injuries caused by the collapse of dwellings, and the peak of medical demand was 12 hours after the earthquake and significantly increased demand for care lasted as long as 3 days. Furthermore, the regression model indicated that 78.5% of the variation of locality-age-sex-specific mortality was explained by the intensity of the earthquake, age, population density, distance to epicenter, medical beds per 10,000 people, and physicians per 10,000 people. CONCLUSION: The results implied that fragile minorities, specifically the elderly and children, require special consideration and attention in regard to disaster rescue and emergency medical care allocation. Epidemiologic analysis can guide disaster response and preparation.