Influenza: current threat from avian influenza.

Influenza is an infectious respiratory pathogen causing annual outbreaks and infrequent pandemics, resulting in significant morbidity, mortality and burdens on the delivery of health care. The geographical spread of highly pathogenic avian influenza (HPAI) H5N1 among poultry and wild bird populations is unprecedented. Growing numbers of sporadic avian influenza infections are occurring in humans, increasing the threat of the next influenza pandemic. Vaccines are the principle means of combating influenza, and a number of studies with H5N1 vaccine candidates are underway. Antiviral agents can be used to treat influenza infection and can be taken as chemoprophylaxis during influenza outbreaks. Oseltamivir has been stockpiled as part of influenza pandemic preparedness planning; however, the emergence of drug resistance may limit its clinical use.