Avian and human influenza: past, present and future

Abstract

Review of the epidemiology of influenza in the last years, particularly in regard to the present avian influenza epidemics. In the past century, 3 severe human influenza pandemics caused by avian A virus rapidly spread throughout the world. According to clinical, laboratory and epidemiological evidences, risk of a new human pandemics exists caused by a high pathogenic avian influenza virus strain, being migratory birds its main carriers. Initiated in Hong-Kong in 2003, it rapidly extended to population in Turkey, Rusia, Macedonia and Colombia; Chile has not been affected yet. Bird-human transmission has been documented in a limited number of cases, all in Asia and half of them fatal, but the greatest hazard is that a new virus strain could acquire, by genetic rearrangement, the ability to infect humans and disseminate among them in an explosive way. The indications and limitations of its prevention and treatment are discussed, including epidemiologic surveillance, use of antiviral drugs and vaccines.