BACKGROUND Influenza viral load (VL) can be a decisive factor in determining the antiviral efficacy in viral clearance. OBJECTIVE This study aimed to evaluate the rate of infection and the role of influenza VL on the clinical spectrum of illnesses among different patient groups attended at a tertiary hospital in Brazil. METHODS Samples were collected from patients presenting acute respiratory infection from 2009 to 2013. Overall, 2262 samples were analysed and distributed into three groups: (i) asymptomatic (AS); (ii) symptomatic outpatients (OP); and (iii) hospitalised patients (HP). VL (expressed in Log10 RNA copies/mL) was calculated through a quantitative real-time one-step reverse transcription-polymerase chain reaction (RT-PCR) assay aimed at the M gene, with human RNAseP target as internal control and normalising gene of threshold cycle values. FINDINGS A total of 162 (7.16%) H1N1pdm09 positive samples were analysed. Patients aged from 0.08 to 77 years old [median ± standard deviation (SD): 12.5 ± 20.54]. Children with 5 to 11 years old presented the highest detection (p < 0.0001). AS patients had the lowest VL, with a significant difference when compared with symptomatic patients (p = 0.0003). A higher VL was observed within two days of disease onset. Ten patients (HP group) received antiviral treatment and were followed up and presented a mean initial VL of 6.64 ± 1.82. A complete viral clearance for 50% of these patients was reached after 12 days of treatment. MAIN CONCLUSIONS It is important to evaluate AS patients as potential spreaders, as viral shedding was still present, even at lower VL. Our results suggest that patients with underlying diseases and severe clinical symptoms may be considered for prolonged viral treatment.

中文翻译：

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不同临床表现的患者中的甲型流感（H1N1）pdm09感染和病毒载量分析。

背景技术流感病毒载量（VL）可能是决定病毒清除中抗病毒功效的决定性因素。目的本研究旨在评估在巴西一家三级医院就诊的不同患者群体的感染率以及VL流感对疾病临床范围的作用。方法收集2009年至2013年急性呼吸道感染患者的样本。总共分析了2262份样本，并将其分为三组：（i）无症状（AS）；（ii）有症状的门诊病人；（iii）住院病人（HP）。VL（以Log10 RNA拷贝/ mL表达）是通过针对M基因的实时定量一步反转录聚合酶链反应（RT-PCR）分析计算得出的，以人RNAseP靶标作为内部控制并标准化阈值循环值的基因。结果共分析了162个（7.16％）H1N1pdm09阳性样品。0.08至77岁的患者[中位数±标准差（SD）：12.5±20.54]。5至11岁的儿童检出率最高（p <0.0001）。AS患者的VL最低，与有症状的患者相比有显着性差异（p = 0.0003）。在疾病发作的两天内观察到较高的VL。10名患者（HP组）接受了抗病毒治疗并接受随访，平均初始VL为6.64±1.82。治疗12天后，这些患者中有50％达到了完全的病毒清除率。主要结论重要的是，评估AS患者是否为潜在的传播者，因为仍然存在病毒脱落，即使在较低的VL下 我们的结果表明，患有潜在疾病和严重临床症状的患者可以考虑延长病毒治疗时间。