Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom.
PLoS Med. 2011 Oct;8(10):e1001109. doi: 10.1371/journal.pmed.1001109. Epub 2011 Oct 18.
Outbreaks of poliomyelitis in African countries that were previously free of wild-type poliovirus cost the Global Polio Eradication Initiative US$850 million during 2003-2009, and have limited the ability of the program to focus on endemic countries. A quantitative understanding of the factors that predict the distribution and timing of outbreaks will enable their prevention and facilitate the completion of global eradication.
Children with poliomyelitis in Africa from 1 January 2003 to 31 December 2010 were identified through routine surveillance of cases of acute flaccid paralysis, and separate outbreaks associated with importation of wild-type poliovirus were defined using the genetic relatedness of these viruses in the VP1/2A region. Potential explanatory variables were examined for their association with the number, size, and duration of poliomyelitis outbreaks in 6-mo periods using multivariable regression analysis. The predictive ability of 6-mo-ahead forecasts of poliomyelitis outbreaks in each country based on the regression model was assessed. A total of 142 genetically distinct outbreaks of poliomyelitis were recorded in 25 African countries, resulting in 1-228 cases (median of two cases). The estimated number of people arriving from infected countries and <5-y childhood mortality were independently associated with the number of outbreaks. Immunisation coverage based on the reported vaccination history of children with non-polio acute flaccid paralysis was associated with the duration and size of each outbreak, as well as the number of outbreaks. Six-month-ahead forecasts of the number of outbreaks in a country or region changed over time and had a predictive ability of 82%.
Outbreaks of poliomyelitis resulted primarily from continued transmission in Nigeria and the poor immunisation status of populations in neighbouring countries. From 1 January 2010 to 30 June 2011, reduced transmission in Nigeria and increased incidence in reinfected countries in west and central Africa have changed the geographical risk of polio outbreaks, and will require careful immunisation planning to limit onward spread. Please see later in the article for the Editors' Summary.
2003-2009 年期间，先前无野生型脊灰病毒的非洲国家爆发脊灰疫情，耗费全球消灭脊灰行动 8.5 亿美元，并且限制了该项目对流行国家的关注。对可预测脊灰疫情分布和时间的因素进行定量了解，将有助于预防疫情并推动全球消灭脊灰进程。
通过对急性弛缓性麻痹病例的常规监测，确定了 2003 年 1 月 1 日至 2010 年 12 月 31 日期间非洲的脊灰病例，同时使用 VP1/2A 区病毒的遗传相关性，对与输入野生型脊灰病毒相关的单独暴发进行了定义。使用多变量回归分析，对 6 个月期间脊灰疫情暴发的数量、规模和持续时间与潜在解释变量的相关性进行了检验。评估了基于回归模型对各国脊灰疫情 6 个月提前预报的预测能力。在 25 个非洲国家共记录了 142 起具有遗传差异的脊灰暴发，造成 1-228 例病例（中位数为 2 例）。从感染国家抵达的人数和 5 岁以下儿童死亡率是与暴发数量相关的独立因素。基于患有非脊灰性急性弛缓性麻痹儿童报告的免疫接种史的免疫接种覆盖率与每个暴发的持续时间和规模以及暴发数量相关。一个国家或地区的 6 个月暴发数量预测随时间变化而变化，预测能力为 82%。
脊灰疫情的暴发主要是由于尼日利亚持续传播以及邻国人群免疫接种状况不佳所致。自 2010 年 1 月 1 日至 2011 年 6 月 30 日，尼日利亚传播减少和西非和中非重新感染国家的发病率增加改变了脊灰暴发的地理风险，需要精心的免疫规划以限制疫情蔓延。请在文章稍后查看编辑摘要。
