ABC - DEF - GHI - JKL - MNO - PQRS - TUV - WXYZ Avian influenza
Similar term(s): bird flu, avian flu.
Definition:
Avian influenza, or "bird flu", is a contagious disease of animals caused by viruses that normally infect only birds and, less commonly, pigs. Avian influenza viruses are highly species-specific, but have, on rare occasions, crossed the species barrier to infect humans.
Source & ©:
WHO
Avian influenza frequently asked questions 
More:
The widespread persistence of the H5N1 - a highly pathogenic [disease-causing] strain of avian influenza - in poultry populations poses two main risks for human health.
The first is the risk of direct infection when the virus passes from poultry to humans, resulting in very severe disease. Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of cases of severe disease and death in humans.
A second risk, of even greater concern, is that the virus - if given enough opportunities - will change into a form that is highly infectious for humans and spreads easily from person to person. Such a change could mark the start of a global outbreak (a pandemic).
Hong Kong has experienced two outbreaks in the past. In 1997, in the first recorded instance of human infection with H5N1, the virus infected 18 people and killed 6 of them. In early 2003, the virus caused two infections, with one death, in a Hong Kong family with a recent travel history to southern China.
Related words: Epidemic - Pandemic
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