Mostaço-Guidolin Luiz C, Bowman Chris S, Greer Amy L, Fisman David N, Moghadas Seyed M
Centre for Disease Modelling, Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada.
BMJ Open. 2012 Sep 1;2(5). doi: 10.1136/bmjopen-2012-001614. Print 2012.
During the first wave of the 2009 influenza pH1N1, disease burden was distributed in a geographically heterogeneous fashion. It was particularly high in some remote and isolated Canadian communities when compared with urban centres. We sought to estimate the transmissibility (the basic reproduction number) of pH1N1 strain in some remote and isolated Canadian communities.
A discrete time susceptible-exposed-infected transmission model was fit to infection curves simulated from laboratory-confirmed case counts for pH1N1 on each day. The sampling from Poisson distribution was used to estimate the basic reproduction number, R(0), of pH1N1 during the spring wave for five different communities in Manitoba and Nunavut, Canada, where remote and isolated communities experienced a high incidence of infection, and high rates of hospitalisation and intensive care unit admission.
Remote and isolated communities in Northern Manitoba, Nunavut, and the largest urban centre (Winnipeg) in the province of Manitoba, Canada.
Using published values of the exposed and infectious periods specific to H1N1 infection, corresponding to the average generation time of 2.78 days, we estimated a mean value of 2.26 for R(0) (95% CI 1.57 to 3.75) in a community located in northern Manitoba. Estimates of R(0) for other communities in Nunavut varied considerably with higher mean values of 3.91 (95% CI 3.08 to 4.87); 2.03 (95% CI 1.50 to 3.19); and 2.45 (95% CI 1.68 to 3.44). We estimated a lower mean value of 1.57 (95% CI 1.35 to 1.87) for R(0) in the Winnipeg health region, as the largest urban centre in Manitoba.
Influenza pH1N1 appears to have been far more transmissible in rural and isolated Canadian communities than other large urban areas. The differential severity of the pandemic in these regions may be explained partly by differential transmissibility, and suggests the need for more nuanced, targeted or population-specific control strategies in Canada.
在2009年甲型H1N1流感第一波疫情期间，疾病负担在地理上分布不均。与城市中心相比，加拿大一些偏远和孤立社区的疾病负担尤其高。我们试图估计甲型H1N1流感病毒株在加拿大一些偏远和孤立社区的传播能力（基本再生数）。
采用离散时间易感-暴露-感染传播模型，拟合根据甲型H1N1流感实验室确诊病例数模拟的每日感染曲线。利用泊松分布抽样估计加拿大曼尼托巴省和努纳武特地区五个不同社区甲型H1N1流感春季疫情期间的基本再生数R(0)，这些偏远和孤立社区感染率高，住院率和重症监护病房入住率也高。
加拿大曼尼托巴省北部、努纳武特地区的偏远和孤立社区，以及曼尼托巴省最大的城市中心（温尼伯）。
利用已公布的甲型H1N1流感感染暴露期和传染期数值，对应平均代间距2.78天，我们估计位于曼尼托巴省北部一个社区的R(0)平均值为2.26（95%可信区间1.57至3.75）。努纳武特地区其他社区的R(0)估计值差异很大，较高的平均值分别为3.91（95%可信区间3.08至4.87）；2.03（95%可信区间1.50至3.19）；以及2.45（95%可信区间1.68至3.44）。作为曼尼托巴省最大的城市中心，我们估计温尼伯卫生区的R(0)平均值较低，为1.57（95%可信区间1.35至1.87）。
甲型H1N1流感在加拿大农村和孤立社区的传播能力似乎远高于其他大城市地区。这些地区大流行的不同严重程度可能部分归因于传播能力的差异，这表明加拿大需要更细致、有针对性或针对特定人群的控制策略。
