AVIAN INFLUENZA AS AN EMERGING INFECTION

Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus. Wild birds are the major natural hosts of the virus and the virus circulates among birds worldwide. The virus has been first isolated from birds (terns) in Africa in 1961. Migratory waterfowl, especially wild ducks are the natural reservoir of avian influenza viruses, and these are also the most resistant birds to infection. The disease is very contagious among birds and may cause death, particularly in domesticated birds like chickens. Infected birds shed virus with their saliva, nasal secretions, and feces. Live bird markets also play an important role in the spread of epidemics. Studies at the genetic level have determined that the virus can jump directly from birds to human. In 1997. the first instance of direct bird to human transmission of influenza A virus was documented during an outbreak of avian influenza among poultry in Hong Kong; the virus caused severe respiratory illness in 18 people, of whom 6 died. The first reported evidence of person-to-person transmission was at the end of the February 2003 in the Netherlands. If avian influenza virus is able to infect people, it may gain the ability to spread easily from person to person, and a new influenza pandemic may begin.