How Bad Can a Crisis Be If It Does Not Top the News?

Sudden onset of front-page news about the U.S. financial crisis, beginning September 6, 2008, may have exacerbated underlying financial problems and facilitated the spread of risk panic to other nations.     

Exact Bayesian Inference and Model Selection for Stochastic Models of Epidemics Among a Community of Households

Abstract.  Much recent methodological progress in the analysis of infectious disease data has been due to Markov chain Monte Carlo (MCMC) methodology. In this paper, it is illustrated that rejection sampling can also be applied to a family of inference problems in the context of epidemic models, avoiding the issues of convergence associated with MCMC methods. Specifically, we consider models for epidemic data arising from a population divided into households. The models allow individuals to be potentially infected both from outside and from within the household. We develop methodology for selection between competing models via the computation of Bayes factors. We also demonstrate how an initial sample can be used to adjust the algorithm and improve efficiency. The data are assumed to consist of the final numbers ultimately infected within a sample of households in some community. The methods are applied to data taken from outbreaks of influenza.     

A Quantitative Assessment of the Risk for Highly Pathogenic Avian Influenza Introduction into Spain via Legal Trade of Live Poultry

Highly pathogenic avian influenza (HPAI) is considered one of the most important diseases of poultry. During the last 9 years, HPAI epidemics have been reported in Asia, the Americas, Africa, and in 18 countries of the European Union (EU). For that reason, it is possible that the risk for HPAI virus (HPAIV) introduction into Spain may have recently increased. Because of the EU free‐trade policy and because legal trade of live poultry was considered an important route for HPAI spread in certain regions of the world, there are fears that Spain may become HPAIV‐infected as a consequence of the legal introduction of live poultry. However, no quantitative assessment of the risk for HPAIV introduction into Spain or into any other EU member state via the trade of poultry has been published in the peer‐reviewed literature. This article presents the results of the first quantitative assessment of the risk for HPAIV introduction into a free country via legal trade of live poultry, along with estimates of the geographical variation of the risk and of the relative contribution of exporting countries and susceptible poultry species to the risk. The annual mean risk for HPAI introduction into Spain was estimated to be as low as 1.36 × 10⁻³, suggesting that under prevailing conditions, introduction of HPAIV into Spain through the trade of live poultry is unlikely to occur. Moreover, these results support the hypothesis that legal trade of live poultry does not impose a significant risk for the spread of HPAI into EU member states.     

Influenza Infection Risk and Predominate Exposure Route: Uncertainty Analysis

An effective nonpharmaceutical intervention for influenza interrupts an exposure route that contributes significantly to infection risk. Herein, we use uncertainty analysis (point‐interval method) and Monte Carlo simulation to explore the magnitude of infection risk and predominant route of exposure. We utilized a previously published mathematical model of a susceptible person attending a bed‐ridden infectious person. Infection risk is sensitive to the magnitude of virus emission and contact rates. The contribution of droplet spray exposure to infection risk increases with cough frequency, and decreases with virus concentration in cough particles. We consider two infectivity scenarios: greater infectivity of virus deposited in the upper respiratory tract than virus inhaled in respirable aerosols, based on human studies; and equal infectivity in the two locations, based on studies in guinea pigs. Given that virus have equal probability of infection throughout the respiratory tract, the mean overall infection risk is 9.8 × 10^?2 (95th percentile 0.78). However, when virus in the upper respiratory tract is less infectious than inhaled virus, the overall infection risk is several orders of magnitude lower. In this event, inhalation is a significant exposure route. Contact transmission is important in both infectivity scenarios. The presence of virus in only respirable particles increases the mean overall infection risk by 1–3 orders of magnitude, with inhalation contributing ≥ 99% of the infection risk. The analysis indicates that reduction of uncertainties in the concentration of virus in expiratory particles of different sizes, expiratory event frequency, and infectivity at different sites in the respiratory tract will clarify the predominate exposure routes for influenza.     

我国畜牧业的现状、问题及对策

文章揭示了我国畜牧业发展现状和存在的环境污染与生态破坏、分散养殖与动物疫病防治的矛盾、投入品使用不规范、资源短缺等问题及其产生的原因,在此基础上提出了发展生态畜牧业的6大对策措施和政策建议。     

Effect of Pediatric Influenza on Caregivers’ Burden—A Literature Review

Influenza, or the flu, is a common and potentially serious infection that disproportionally affects children with more than 20,000 yearly hospitalizations in children under the age of 5. A literature review of the caregiver burden associated with pediatric influenza was conducted. Two main types of burdens were identified: economic and noneconomic. Flu treatment costs $3,990 for pediatric inpatients services and $730 for emergency department (ED) pediatric patients. Caregivers may also face out-of-pocket costs ($178 for inpatients, $125 for ED patients, and $52 for outpatients) or those not covered by health insurance. Caregivers can also face indirect costs while caring for their children with the flu. Indirect costs were common, and 75% of pediatric caregivers reported these costs when caring for a sick child. Missed work is the most common indirect cost and is estimated as high as 73 work hours ($1,456) missed while caring for a sick child. Other costs associated with pediatric influenza included noneconomic burden: sudden changes in daily life, loss of leisure time, social disruption, and psychological impact or stress. Noneconomic burdens were also found to be significant and lowered the quality of life of caregivers even after the child’s illness. Socioeconomic status is an important predictor of influenza rates. Residents in high-poverty areas are three times more likely to have hospitalizations due to pediatric influenza than those in low-poverty areas. From the literature it is evident that pediatric influenza has demonstrated a considerable impact on caregivers’ lives both financially and in other aspects.     

Dose-response assessment for influenza A virus based on data sets of infection with its live attenuated reassortants

Reported data sets on infection of volunteers challenged with wild-type influenza A virus at graded doses are few. Alternatively, we aimed at developing a dose-response assessment for this virus based on the data sets for its live attenuated reassortants. Eleven data sets for live attenuated reassortants that were fit to beta-Poisson and exponential dose-response models. Dose-response relationships for those reassortants were characterized by pooling analysis of the data sets with respect to virus subtype (H1N1 or H3N2), attenuation method (cold-adapted or avian-human gene reassortment), and human age (adults or children). Furthermore, by comparing the above data sets to a limited number of reported data sets for wild-type virus, we quantified the degree of attenuation of wild-type virus with gene reassortment and estimated its infectivity. As a result, dose-response relationships of all reassortants were best described by a beta-Poisson model. Virus subtype and human age were significant factors determining the dose-response relationship, whereas attenuation method affected only the relationship of H1N1 virus infection to adults. The data sets for H3N2 wild-type virus could be pooled with those for its reassortants on the assumption that the gene reassortment attenuates wild-type virus by at least 63 times and most likely 1,070 times. Considering this most likely degree of attenuation, 10% infectious dose of H3N2 wild-type virus for adults was estimated at 18 TCID50 (95% CI = 8.8-35 TCID50). The infectivity of wild-type H1N1 virus remains unknown as the data set pooling was unsuccessful.     

New Health Risks and Sociocultural Contexts: Bird Flu Impacts on Consumers and Poultry Businesses in Lao PDR

Avian flu has been identified as one of the most challenging new risks, global in impact due to the "highly interconnected and integrated world economy along with other unpredictable events such as the Asian financial crisis and global terrorism." We have chosen the case of Lao PDR to shed light on an area in which local people consume chicken as one of their staple foods. Our research analyzes consumer behavior, poultry business modification patterns in a high-risk country, and government reaction for business resilience. The geographic choice is motivated by the 2006 EIU report on Catastrophe Risk Management that indicated that Asian-Pacific companies are better prepared for such risks as bird flu than European business is, despite the many cases found in both regions.     

从"猪流感"到"甲型H1N1流感"——谈汉语引进术语的科学性和民族性

目前世界上正在流行的流感,最初被称为“猪流感”,又有多种命名,后来被称为“A（H1N1）”,汉语用“甲型H1N1”去指称。汉语对这一学科术语的引入具有科学性,又具有民族性,具有中文、英文合璧的意味。     

MODELLING EPIDEMIC DISEASES

This paper traces the development of mathematical models for epidemics from the 18th century to the present day. The models are shown to be of use in predicting and controlling the spread of infection.