Etiology of Acute Respiratory Infections during an Outbreak in Al-Marj City, Libya: A Descriptive Cross-sectional Study, November 2025

Abstract

Acute respiratory infections (ARIs) are a leading cause of morbidity and mortality worldwide, particularly during seasonal outbreaks. In November 2025, an unusual increase in respiratory illness was reported in Al-Marj City, Libya. A descriptive outbreak investigation was conducted. A total of 43 nasopharyngeal swab samples were collected from suspected cases and tested at the national reference laboratory for influenza A and B, SARS-CoV-2, and respiratory syncytial virus (RSV). Epidemiological data, including age, sex, residence, and clinical severity, were analyzed. Thirty out of 43 samples (69.8%) were positive for influenza A, while all samples tested negative for influenza B, SARS-CoV-2, and RSV. Most confirmed cases were reported from Al-Marj municipality (25 cases). Children under five years and adults aged 50 years and above were the most affected age groups. Sixteen cases were managed at outpatient clinics, seven required hospitalizations, and seven were admitted to intensive care units. Influenza A was identified as the primary causative agent of the outbreak. Strengthening laboratory-supported surveillance systems is essential for early outbreak detection and effective public health response in Libya.