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

Abstract

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.