About the Avian Flu Disease In Birds

Avian Flu has had a devastating impact on the poultry industry wherever it has been detected.  Currently, Asian countries (most notably Hong Kong, Vietnam, China, and Thailand) have been the hardest hit areas over the past few years.  Severe epidemics in isolated areas have led to the destruction of millions of ducks, chickens, geese, and turkeys to prevent further spread of this contagious disease. 

The Avian Flu disease is cause by Type A Influenza Virus.  The Influenza Virus is from the virus family Orthomyxoviridae.  All of these influenza viruses are negative-sense, single stranded, segmented RNA.  To date, there have been fifteen subtypes of Avian Flu viruses found worldwide in birds.  It is believed that all birds are susceptible to infection by the virus, although there is variation in the disease-resistance amongst bird species and populations.  That is, some birds can be infected with the virus but show no signs of disease.  Domestic poultry (chicken, turkey, some ducks and geese) are highly susceptible to avian flu, which is why they are the ones most heavily impacted.  In comparison, migratory waterfowl  (most notably wild ducks) show relatively little signs of disease even if the virus is detected in them.  These birds may act as reservoirs, or carriers, of the virus. 

Of these Avian Flu subtypes, some of them are mildly of low pathogenic meaning that the illness they cause are relatively less severe than those that are highly pathogenic  The highly pathogenic avian flu is characterized by being highly contagious and causing mass mortalities of birds in a short period of time.  Mortalities have approached 100% in many incidences reported.  To date, all outbreaks of highly pathogenic avian flu has been caused by viruses of subtypes H5 and H7.