Pandemic Influenza: A Review

This essay, written ten years after the first human death from avian influenza, reviews scientific, social, and policy aspects of pandemic influenza, and asks whether the near‐crisis level of concern is justified. That there will be another influenza pandemic is certain, and a number of factors suggest it will occur sooner rather than later. It is impossible, however, to predict two of the pandemic's crucial characteristics—its pathogenicity and the age‐attack curve. The scientific arsenal has never been stronger, yet gaps in the availability of antiviral drugs and vaccines are inevitable, and the world is poorly prepared to cope with the politics of drug shortage. Some studies suggest emergent pandemics can be “ring‐fenced,” but these studies are not broadly accepted. Assuming that they cannot, rapid and global deployment of a range of responses, including social distancing, travel limitations, and prophylactic/curative application of antiviral drugs such as Tamiflu, can limit impacts. However, the impacts are bound to be significant if not severe. Overall health‐sector strengthening, rural development (particularly in the area of veterinary health), and addressing the local, national, and international governance issues that cut across all aspects of infectious disease are more likely to bear fruit, especially in the developing world, than the pandemic preparedness planning now in vogue.     

Ecological Risk Assessment Conceptual Model Formulation for Nonindigenous Species

This article addresses the application of ecological risk assessment at the regional scale to the prediction of impacts due to invasive or nonindigenous species (NIS). The first section describes risk assessment, the decision-making process, and introduces regional risk assessment. A general conceptual model for the risk assessment of NIS is then presented based upon the regional risk assessment approach. Two diverse examples of the application of this approach are presented. The first example is based upon the dynamics of introduced plasmids into bacteria populations. The second example is the application risk assessment approach to the invasion of a coastal marine site of Cherry Point, Washington, USA by the European green crab. The lessons learned from the two examples demonstrate that assessment of the risks of invasion of NIS will have to incorporate not only the characteristics of the invasive species, but also the other stresses and impacts affecting the region of interest.     

A general caxedorical data memddology for evaluating medical diagnostic tests

Measures of sensitivity, predictive accuracy, and agreement are currently used to evaluate the efficiency of diagnostic tests reported on dichotomous scales. This paper presents a unified approach to the evaluation of diagnostic tests in terns of generalized Lnuices of sensitivity, misclassification, predictive accuracy and inaccuracy, classification agreement and prediction agreement for polytomous measurement scales. It Is sufficiently general to accommodate additional complications of study design factors such as multiple testing, known and unknown disease prevalence distributions, and multiple subpopulations defined by the cross-classification of independent factors. Estimation and hypothesis testing are developed within a general linear models approach to the analysis of categorical data from repeated measurement lesigns using weighted least squares computations. This methodology is illustrated within the context of data from a. large cotmiunity-based epidemiologic study of obstructive airways disease,Two diagnostic criteria for inpaired lung function are compared on the basis of their generalized sensitivity and classification agreement measures. The outcomes of the tests are reported on the same three-point scale (normal, questionable, impaired) and are examined within several subpopulations determined by age and sex.