Gastrointestinal, Emerging and Zoonotic Infections Department, Centre for Infections, Health Protection Agency, London, United Kingdom.
PLoS One. 2009 Aug 24;4(8):e6671. doi: 10.1371/journal.pone.0006671.
Norovirus, the most commonly identified cause of both sporadic cases and outbreaks of infectious diarrhoea in developed countries, exhibits a complex epidemiology and has a strong wintertime seasonality. Viral populations are dynamic and evolve under positive selection pressure.
Time series-adapted Poisson regression models were fitted to daily counts of laboratory reports of norovirus in England and Wales from 1993 to 2006.
Inverse linear associations with daily temperature over the previous seven weeks (rate ratio (RR) = 0.85; 95% CI: 0.83 to 0.86 for every 1 degrees C increase) and relative humidity over the previous five weeks (RR = 0.980; 95% CI: 0.973 to 0.987 for every 1% increase) were found, with temperature having a greater overall effect. The emergence of new norovirus variants (RR = 1.16; 95% CI: 1.10 to 1.22) and low population immunity were also associated with heightened norovirus activity. Temperature and humidity, which may be localised, had highly consistent effects in each region of England and Wales.
These results point to a complex interplay between host, viral and climatic factors driving norovirus epidemic patterns. Increases in norovirus are associated with cold, dry temperature, low population immunity and the emergence of novel genogroup 2 type 4 antigenic variants.
诺如病毒是造成发达国家散发性病例和感染性腹泻暴发的最常见原因，其具有复杂的流行病学特征，且具有强烈的冬季季节性。病毒群体是动态的，并在正选择压力下进化。
对 1993 年至 2006 年英格兰和威尔士实验室报告的诺如病毒的每日数据进行时间序列适应泊松回归模型拟合。
在前 7 周的每日温度呈负线性相关（率比（RR）= 0.85；95%CI：每增加 1 摄氏度，0.83 至 0.86），前 5 周的相对湿度呈负线性相关（RR = 0.980；95%CI：每增加 1%，0.973 至 0.987），温度的整体影响更大。新的诺如病毒变异体的出现（RR = 1.16；95%CI：1.10 至 1.22）和人群免疫力低下也与诺如病毒活性增加有关。可能本地化的温度和湿度在英格兰和威尔士的每个地区都有高度一致的影响。
这些结果表明，宿主、病毒和气候因素之间的复杂相互作用推动了诺如病毒的流行模式。诺如病毒的增加与寒冷、干燥的温度、人群免疫力低下以及新型基因 2 型 4 抗原变异体的出现有关。
