The clinical features of uncomplicated influenza are virtually indistinguishable from those of other respiratory viral infections. Influenza is classically characterized by an abrupt onset of headache, high-grade fever, chills, dry cough, pharyngeal irritation, myalgias, malaise, and anorexia. The fever lasts an average of 3 days (range of 2 to 8 days). The cough, initially nonproductive and nonpurulent, may persist for weeks. Bronchial hyper-reactivity and small-airway dysfunction are often present in influenza virus infection. In the presence of asthma or structural lung disease, wheezing may be a prominent manifestation [24] . Vomiting and diarrhea, while rare in seasonal influenza, have been frequently reported in infections with the 2009 pandemic influenza A H1N1v strain [10] , particularly in children.