Susceptibility of Poultry to Pandemic (H1N1) 2009 Virus

Patients admitted to the hospital with pulmonary infi ltrates were empirically treated with high dose oseltamivir (150 mg 2×/d) for 5 days, other antimicrobial drugs, and, eventually, steroids. In 2 patients, the respiratory disease progressed initially but they eventually recovered; 2 patients (1.2% of admissions to hospital) with acute respiratory failure died. Despite improvement in clinical symptoms at discharge, chest radiographs performed on a limited number of patients showed no substantial changes at 72–96 h after admission. Clinical manifestations of pandemic (H1N1) 2009 have not yet been fully characterized. We observed a mild to moderate lower respiratory disease in ≈8% of consecutive patients with ILI during the current pandemic in Argentina. A more severe respiratory disease was observed in Mexico during the current pandemic (4) In contrast, early reports indicated that pandemic (H1N1) 2009 disease might be similar in severity to seasonal infl uenza (3). A lack of microbiologic confi rmation may bias our observation. Because pulmonary infi ltrates are uncommon in previously healthy persons with ILI, a simultaneous circulation of other respiratory pathogens may explain our observation. Furthermore, early empirical use of antimicrobial drugs could overshadow clinical features of bacterial pneumonia. We observed an unexpectedly high rate of lower respiratory disease in adults with ILI during an outbreak of pandemic (H1N1) 2009 in Argentina. This fi nding suggests that a unique pattern of virulence, pulmonary tropism, or both may characterize the current infl uenza A (H1N1) infection, although we could not rule out co-infection with other viral or bacterial respiratory pathogens. Considering the evolving nature of infl uenza viruses, the wide clinical spectrum of pandemic (H1N1) 2009 should be further investigated. Carlos Zala and Roberto Gonzalez Author affi liation: Hospital Central de San Isidro, Buenos Aires, Argentina