Conflicts of interest: nothing to declare.
Prospective evaluation of epidemiological, clinical, and microbiological features of pandemic influenza A (H1N1) virus infection in Italy†
Article first published online: 19 OCT 2011
Copyright © 2011 Wiley Periodicals, Inc.
Journal of Medical Virology
Volume 83, Issue 12, pages 2057–2065, December 2011
How to Cite
Fabbiani, M., Sali, M., Di Cristo, V., Pignataro, G., Prete, V., Farina, S., D'Avino, A., Manzara, S., dal Verme, L. Z., Silveri, N. G., Cauda, R., Delogu, G., Fadda, G. and Di Giambenedetto, S. (2011), Prospective evaluation of epidemiological, clinical, and microbiological features of pandemic influenza A (H1N1) virus infection in Italy. J. Med. Virol., 83: 2057–2065. doi: 10.1002/jmv.22231
- Issue published online: 19 OCT 2011
- Article first published online: 19 OCT 2011
- Manuscript Accepted: 22 AUG 2011
- swine flu;
- respiratory tract infection;
- viral infection
Since several characteristics of pandemic influenza A (H1N1) virus infection remain to be determined, this study aimed to describe clinical features and complications of patients infected with H1N1. Subjects affected by influenza-like illnesses and a control group of asymptomatic patients were enrolled prospectively at an Emergency Department from October 2009 to April 2010. At enrollment, clinical data and nasopharyngeal swabs for virological analyses were obtained. Ill subjects were followed until recovery and swabs were collected weekly in patients infected with H1N1. Of 318 patients enrolled, 92 (28.9%) were positive to H1N1. Patients infected with H1N1 were mainly young adults and complained classic influenza-like symptoms. Fever was observed for a median time of 5 (IQR 3–7) days. Hospitalization occurred in 27.7% with 2% requiring intensive care unit admission: median length of hospitalization was 6 days (IQR 5–9). Pneumonia was diagnosed in 19.6% of patients. A similar proportion of lower airways involvement and of clinical complications was observed in subjects testing positive or negative for H1N1. However, patients infected with H1N1 were younger and hospitalized for a shorter period as compared to the control group (P = 0.002 and P = 0.045, respectively). Older age, asthma/chronic obstructive pulmonary disease and hypertension were associated with an increased risk of pneumonia. Viral shedding was observed for at least 1 week in 21.3% of patients. Asymptomatic infection was uncommon (1.1%). Respiratory syndromes caused by H1N1 and factors associated with disease severity were investigated and compared to influenza-like illnesses of other origin. Such findings might contribute to improve clinical and epidemiological management of the disease. J. Med. Virol. 83:2057–2065, 2011. © 2011 Wiley Periodicals, Inc.