世卫组织将继续要求这些国家对首例确诊病例作出报告，并要求尽可能提供每周汇总病例数目，同时提供早期病例的描述性流行病学情况。
WHO will continue to request that these countries report the first confirmed cases and, as far as feasible, provide weekly aggregated case numbers and descriptive epidemiology of the early cases.
背景资料概要。在普通人群中存在胸MRI表现描述性流行病学的缺乏。
Summary of Background Data. There is a dearth of descriptive epidemiology of thoracic MRI findings in the general population.
方法利用描述性流行病学方法对1991 ~ 2000年百日咳发病、免疫和监测等资料进行分析。
Methods The data of morbidity and immune surveillance of pertussis in 1991-2000 was analyzed by descriptive epidemiology.
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