Avian Influenza

( Introduction )

Since the beginning of time human beings have been plagued with diseases, ranging from the common cold to deadly cancers. There have been severe outbreaks of numerous diseases throughout history, making the risk for another even greater. Scientist have found that an outbreak of Avian Influenza may be on the rise. Now, some of you may be asking yourselves “What is Avian Influenza?” or “What affect will it have on me?” if an outbreak of Avian Influenza were to occur, wouldn’t you feel safer knowing as much as possible about the disease and its history?

( What is Avian Influenza? )

Avian influenza, or “bird flu”, is a contagious virus that traditionally infects only birds and, less frequently, pigs, seldom does it infect humans. It is caused by the influenza strand H5N1. In domesticated poultry, infection with avian influenza viruses causes two main forms of disease, distinguished by low and high extremes of threat. The low pathogenic form causes only mild symptoms: ruffled feathers, a drop in egg production and may easily go undetected. The highly pathogenic form is far more dramatic, it spreads very swiftly through poultry flocks, causing disease that affects multiple internal organs, and has a death rate that can approach 100% -- often within 48 hours. Presently, there is no commercial vaccine widely available, making treatment difficult and near impossible. Influenza A viruses have 16 H subtypes and 9 N subtypes.

( History of the Disease )

Only viruses of the H5 and H7 subtypes are known to cause the highly pathogenic form of the disease. However, not all viruses of the H5 and H7 subtypes are highly pathogenic and not all will cause severe disease. It is believed that H5 and H7 viruses are introduced to poultry flocks in their low pathogenic form and when allowed to circulate in poultry populations the virus can mutate within a few month into the highly pathogenic form. Wild waterfowl are considered the natural reservoir of all influenza A viruses. They are known to carry viruses of the H5 and H7 subtypes, but usually in low pathogenic form. Evidence suggests that migratory birds can introduce low pathogenic H5 and H7 viruses to poultry flocks, which then mutate to the highly pathogenic form. Recent events make it likely that some migratory birds are now directly spreading the H5N1 virus in its highly pathogenic form and further spread to new areas is expected. The current outbreaks, which began in South-east Asia in mid-2003, are the largest and most severe on record. Never before in the history of this