Objective

To explore the contribution of environmental factors in the unusual pattern of influenza activity observed in Brisbane, Australia during the summer of 2018–2019.

Methods

Distributed lag nonlinear models (DLNMs) were used to estimate the effect of environmental factors on weekly influenza incidence in Brisbane. Next generation sequencing was then employed to analyze minor and majority variants in influenza strains isolated from Brisbane children during this period.

Results

There were limited marked differences in the environmental factors observed in Brisbane between the 2018–2019 summer period and the same period of the proceeding years, with the exception of significant reduction in rainfall. DLNM showed that reduced rainfall in Brisbane (at levels consistent with the 2018–2019 period) correlated with a dramatic increase in the relative risk of influenza. Sulfur dioxide (SO₂) levels were also increased in the 2018–2019 period, although these levels did not correlate with an increased risk of influenza. Sequencing of a limited number of pediatric influenza virus strains isolated during the 2018–2019 showed numerous mutations within the viral HA.

Conclusions

Taken together, these data suggest a limited role for key environmental factors in the influenza activity observed in Brisbane, Australia during the summer of 2018–2019. One alternative explanation may that viral factors, in addition to other factors not studied herein, contributed to the unusual influenza season. Our findings provide fundamental information that may be beneficial to a better understanding of the seasonal trends of influenza virus.

中文翻译：

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在2018–2019年澳大利亚夏季期间，环境因素在布里斯班罕见的流感高峰中的作用的证据有限

客观的

探讨环境因素在2018-2019年夏季在澳大利亚布里斯班观察到的流感活动异常模式中的贡献。

方法

分布式滞后非线性模型（DLNMs）用于估计环境因素对布里斯班每周流感发病率的影响。然后，在此期间，采用下一代测序技术分析了从布里斯班儿童分离出的流感毒株中的次要和多数变异。

结果

在布里斯班，2018-2019年夏季至此后数年的同一时期内，所观察到的环境因素差异有限，但降雨量明显减少。DLNM显示，布里斯班的降雨减少（与2018-2019年期间的水平一致）与流感的相对风险急剧增加有关。在2018-2019年期间，二氧化硫（SO ₂）水平也有所增加，尽管这些水平与流感风险的增加无关。在2018-2019年期间分离的有限数量的小儿流感病毒株的测序显示病毒HA内有许多突变。

结论

综上所述，这些数据表明关键环境因素在2018-2019年夏季在澳大利亚布里斯班观察到的流感活动中的作用有限。一种替代解释可能是，除本文未研究的其他因素外，病毒因素也促成了异常的流感季节。我们的发现提供了基本信息，可能有助于更好地了解流感病毒的季节性趋势。