DIFFERENTIAL DIAGNOSIS OF ACUTE RESPIRATORY VIRAL INFECTIONS AND INFLUENZA BASED ON CLINICAL SYMPTOMS: A COMPARATIVE ANALYSIS

Background: Acute Respiratory Viral Infections (ARVI) and Influenza share similar transmission routes and overlapping symptoms, yet they differ significantly in prognosis and management. Misdiagnosis often leads to inappropriate antibiotic use and failure to prescribe specific antivirals for influenza. This study aims to identify the key clinical discriminators between seasonal Influenza and non-influenza ARVI to improve bedside diagnostic accuracy in primary care settings. Methods: A prospective observational study was conducted involving 400 patients presenting with acute respiratory symptoms during the epidemic season. Patients were stratified into two groups based on PCR confirmation: Group 1 (Influenza A/B, n=150) and Group 2 (Non-Influenza ARVI, n=250). Clinical parameters including onset speed, fever magnitude, intoxication signs, and catarrhal symptoms were compared. Results: Influenza was characterized by a hyperacute onset (92% vs 15% in ARVI, p<0.001), high fever >38.5°C (88% vs 22%), and severe systemic intoxication (myalgia, headache) with minimal initial catarrhal symptoms. In contrast, non-influenza ARVI presented with a gradual onset, predominant rhinorrhea, and sneezing. The combination of "Sudden onset + Fever >38°C + Cough + Absence of Runny Nose" had a positive predictive value of 85% for Influenza. Conclusion: While laboratory confirmation is the gold standard, specific clinical constellations allow for reliable early differentiation. Recognizing the "Intoxication-Catarrhal Dissociation" is crucial for the timely administration of neuraminidase inhibitors and the reduction of unnecessary antibiotic prescriptions.背景：急性呼吸道病毒感染（Acute Respiratory Viral Infections, ARVI）与流感有着相似的传播途径与重叠的临床症状，但二者在预后与诊疗方案上存在显著差异。误诊常导致抗生素不合理使用，且无法为流感患者开具针对性的抗病毒药物。本研究旨在明确季节性流感与非流感型ARVI之间的关键临床鉴别指标，以提升基层医疗环境下的床旁诊断准确性。 方法：本研究开展了一项前瞻性观察性研究，纳入400名在流行季因急性呼吸道症状就诊的患者。基于聚合酶链式反应（polymerase chain reaction, PCR）的检测结果对患者进行分层分组：第1组为甲型/乙型流感患者（n=150），第2组为非流感型ARVI患者（n=250）。对比分析了包括起病速度、发热程度、中毒征象与卡他症状在内的多项临床参数。 结果：流感的典型特征为超急性起病（92% vs 非流感ARVI的15%，p<0.001）、体温＞38.5℃的高热（88% vs 22%），以及严重的全身中毒症状（肌痛、头痛），且初始卡他症状轻微。与之相反，非流感型ARVI患者起病较为缓慢，以流涕、喷嚏为主要临床表现。“骤起发病+体温＞38℃+咳嗽+无流涕”的组合指标对流感的阳性预测值达85%。 结论：尽管实验室检测仍是诊断金标准，但特定的临床症候群可实现可靠的早期鉴别。识别“中毒-卡他分离征”对于及时给予神经氨酸酶抑制剂（neuraminidase inhibitors）治疗、减少不必要的抗生素处方至关重要。