Objectives

Invasive meningococcal disease (IMD) is a severe bacterial infection that displays wintertime seasonality in temperate countries. Mechanisms driving seasonality are poorly understood and may include environmental conditions and/or respiratory virus infections. We evaluated the contribution of influenza and environmental conditions to IMD risk, using standardized methodology, across multiple geographical regions.

Methods

We evaluated 3276 IMD cases occurring between January 1999 and December 2011 in 11 jurisdictions in Australia, Canada, France and the United States. Effects of environmental exposures and normalized weekly influenza activity on IMD risk were evaluated using a case-crossover design. Meta-analytic methods were used to evaluate homogeneity of effects and to identify sources of between-region heterogeneity.

Results

After adjustment for environmental factors, elevated influenza activity at a 2-week lag was associated with increased IMD risk (adjusted odds ratio (OR) per standard deviation increase 1.29; 95% confidence interval, 1.04–1.59). This increase was homogeneous across the jurisdictions studied. By contrast, although associations between environmental exposures and IMD were identified in individual jurisdictions, none was generalizable.

Conclusions

Using a self-matched design that adjusts for both coseasonality and case characteristics, we found that surges in influenza activity result in an acute increase in population-level IMD risk. This effect is seen across diverse geographic regions in North America, France and Australia. The impact of influenza infection on downstream meningococcal risk should be considered a potential benefit of influenza immunization programmes.

中文翻译：

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在温带国家，流感会增加侵袭性脑膜炎球菌疾病的风险。

目标

侵袭性脑膜炎球菌病（IMD）是一种严重的细菌感染，在温带国家表现出冬季的季节性。人们对导致季节性的机制知之甚少，其中可能包括环境条件和/或呼吸道病毒感染。我们使用标准化的方法，在多个地理区域中评估了流感和环境条件对IMD风险的贡献。

方法

我们评估了1999年1月至2011年12月之间在澳大利亚，加拿大，法国和美国的11个辖区发生的3276例IMD病例。使用病例交叉设计评估了环境暴露和正常的每周流感活动对IMD风险的影响。使用荟萃分析方法评估效应的同质性，并确定区域间异质性的来源。

结果

在对环境因素进行调整后，流感病毒活动在2周的滞后时间升高与IMD风险增加相关（每标准差调整后的优势比（OR）增加1.29； 95％置信区间1.04–1.59）。在所研究的辖区中，这种增长是均匀的。相比之下，尽管在各个辖区中确定了环境暴露与IMD之间的关联，但没有一个可以推广。

结论

使用针对季节变化和病例特征进行调整的自我匹配设计，我们发现流感活动的激增导致人群水平的IMD风险急剧增加。在北美，法国和澳大利亚的不同地理区域都可以看到这种效果。流感感染对下游脑膜炎球菌风险的影响应被认为是流感免疫计划的潜在好处。