International Journal of Medical Laboratory

Introduction: Influenza is an acute respiratory illness caused by three types of viruses: A, B, and C. Types A and B are responsible for the majority of human infections. This study represents the first epidemiological and laboratory investigation of influenza in Yazd Province in recent years.
Materials and Methods: This study was conducted on patients at Shahid Sadoughi Hospital, with a clinical diagnosis of influenza. Polymerase chain reaction (PCR) tests for influenza B and H1N1 were performed on all patients.
Result: Among these patients, PCR results were positive for 417 patients (73.8%), of which 64 were positive for type B and 353 for subtype H1N1 (62.5%). The remaining patients had other influenza-like illnesses. The clinical outcome for 18 H1N1 patients was death. The most common underlying condition was hypertension, present in 63 patients (11.2%). The most common clinical symptoms of H1N1 were cough, fever, and shortness of breath in 63.5%, 62.3%, and 51.6%, respectively. Platelet counts were significantly lower in both H1N1 and influenza B patients compared to PCR-negative patients (p = 0.002). Neutrophil and lymphocyte percentage differences were most prominent in H1N1 cases, with H1N1 showing the highest neutrophils and lowest lymphocytes (p = 0.001).
Conclusion: Prominent clinical symptoms and laboratory findings, such as decreased platelet counts and altered neutrophil and lymphocyte ratios, were key in supporting the diagnosis of influenza, especially H1N1. While most patients recovered, the higher mortality among H1N1 cases highlights the importance of early diagnosis, prompt treatment, and seasonal preparedness.