Epidemiologic, Clinical and Laboratory Features of Pandemic Influenza (H1N1) 2009 Virus Infection

Introduction: After the definition of the first H1N1 case on 15 April 2009, the first case in our country was reported on 15 May 2009, and the first local case was seen on 18 June 2009. In this study, we evaluated patients hospitalized with a pre-diagnosis of H1N1 virus infection, according to epidemiologic, clinical and laboratory features. Materials and Methods: Cases hospitalized between October 2009 and January 2010 with a pre-diagnosis of pandemic influenza and for whom samples of nasal and oropharyngeal swabs were obtained were included in the study. Epidemiologic and laboratory properties of the cases (for both H1N1 positive and H1N1negative groups) were evaluated, as well as their prognoses and treatment. Results: Between October 2009 and January 2010, 155 patients with pre-diagnoses of H1N1 were hospitalized. Eighty-four H1N1 positive and 71 H1N1 negative patients were evaluated. Cough, fatigue and fever were the most frequently observed symptoms. Obesity, fatigue and diarrhea were more common in the H1N1 negative group. Abnormal chest X-ray, lymphopenia and leukopenia were more common in the H1N1 positive group. The fatality rate was determined as 7.1%. 21.4% of the patients (18/84) required intensive care. Twelve patients were monitored with invasive and 3 with non-invasive mechanical ventilation. None of the patients in the H1N1 negative group required intensive care. In the H1N1 positive group, 69 patients received oseltamivir and 47 patients received oseltamivir and antibiotherapy. Conclusion: The new pandemic influenza virus came under the spotlight because of its fast spread and the complications seen in young patients with no comorbidities, where normally influenza-related complications are not expected. The majority of our cases were young adult patients. Most of the cases hospitalized with H1N1 diagnosis had symptoms similar to pneumonia, low oxygen saturation and deterioration in their general condition. Antiviral treatment initiated during the early phases of the disease was successful. Respiratory support and intensive care play a vital role in the cases in which they are needed. Informing the population about the disease and educating them on its transmission and immunization are very important in preventing its spread