[Influenza virus infection: clinical diagnosis and current considerations]

Point-of-care diagnosis of influenza requires sound recognition of the prevalence of the signs and symptoms of the patients, which would help to define the pattern of clinical presentation of this infection. In severely ill patients, however, clinical features of influenza could be erroneously modified by the exacerbation of co-morbid conditions, resulting in a delay of the diagnosis. Enzymatic rapid diagnostic tests, although establishing the diagnosis with positive result especially when the virus is in high circulation, has relatively poor sensitivity for the 2009 A/H1N1 virus and it varies among the different age groups. Given the likelihood of long-term circulation of the novel H1N1 virus, patients' clinical features and the performance of the rapid tests should continuously be monitored.