Data from: Acute febrile illness and influenza disease burden in a rural cohort dedicated to malaria in Senegal, 2012-2013

Background: African populations are considered to be particularly vulnerable to fever illnesses, including malaria, and acute respiratory disease, owing to limited resources and overcrowding. However, the overall burden of influenza in this context is poorly defined and incidence data for African countries are scarce. We therefore studied the fever syndrome incidence and more specifically influenza incidence in a cohort of inhabitants of Dielmo and Ndiop in Sokone district, Senegal. Methods: Daily febrile-illness data were prospectively obtained from January 2012 to December 2013 from the cohort of the villages of Dielmo and Ndiop, initially dedicated to the study of malaria. Nasopharyngeal swabs were collected from, and malaria diagnosis tests (thick blood smears) carried out on, every febrile individual during clinical visits; reverse transcriptase-polymerase chain reaction was used to identify influenza viruses in the samples. Binomial negative regression analysis was used to study the relationship between the monthly incidence rate and various covariates. Results: In Dielmo and Ndiop, the incidence of malaria has decreased, but fever syndromes remain frequent. Among the 1036 inhabitants included in the cohort, a total of 1,129 episodes of fever were reported. Influenza was present all year round with peaks in October-December 2012 and August 2013. The fever, ILI and influenza incidence density rates differed significantly between age groups. At both sites, the adjusted incidence relative risks for fever syndromes and ILI were significantly higher in the [6–24 months) than other age groups: 7.3 (95%CI: [5.7–9.3]) and 16.1 (95%CI: [11.1–23.3]) respectively. The adjusted incidence relative risk for influenza was significantly higher for the [0–6 months) than other age groups: 9.9 (95%CI: [2.9–33.6]). At both sites, incidence density rates were lowest among adults > = 50 years. Conclusions: In this rural setting in Senegal, influenza was most frequent among the youngest children. Preventive strategies targeting this population should be implemented.

研究背景：受限于医疗资源匮乏与人口拥挤，非洲人群被认为是包括疟疾、急性呼吸道疾病在内的发热性疾病的高危易感群体。然而，该语境下流感的整体疾病负担仍未明确，非洲国家的流感发病数据也十分匮乏。为此，我们针对塞内加尔索科内区迪埃尔莫（Dielmo）和尼奥普（Ndiop）两村的居民队列，开展了发热综合征发病率、尤其是流感发病率的相关研究。

研究方法：本研究队列最初用于疟疾相关研究，我们于2012年1月至2013年12月期间，前瞻性收集了迪埃尔莫与尼奥普两村队列的每日发热疾病数据。临床就诊期间，我们为每一位发热患者采集鼻咽拭子，并开展疟疾诊断检测（厚血涂片法）；同时采用逆转录聚合酶链反应（reverse transcriptase-polymerase chain reaction）对样本中的流感病毒进行鉴定。我们采用负二项回归分析（binomial negative regression），探究月度发病率与各类协变量之间的关联。

研究结果：在迪埃尔莫与尼奥普两村，疟疾发病率有所下降，但发热综合征仍较为频发。本队列纳入的1036名居民中，累计报告发热病例共1129例次。流感全年均有流行，分别在2012年10-12月及2013年8月出现发病高峰。不同年龄组的发热、流感样病例（influenza-like illness, ILI）及流感发病密度存在显著差异。在两个研究地点中，[6~24月龄）人群的发热综合征与流感样病例校正发病相对风险均显著高于其他年龄组，分别为7.3（95%置信区间：5.7~9.3）与16.1（95%置信区间：11.1~23.3）。[0~6月龄）人群的流感校正发病相对风险显著高于其他年龄组，为9.9（95%置信区间：2.9~33.6）。此外，两个地点的发病密度均在≥50岁的成年人群中最低。

研究结论：在塞内加尔这一农村研究场景中，流感在低龄儿童中最为高发，因此应针对该人群制定并实施针对性的预防策略。