The online newspaper Vnexpress quoted Cao Bao Van, director of the Molecule Biology Department of the Pasteur Institute, Vietnam's centre of bird flu research, as saying the decoding of 24 samples of the virus taken from poultry and humans showed significant antigen variation.

An antigen is any foreign substance that stimulates the body's immune system to produce antibodies.

Van said the study had showed an antigenic shift involving major antigenic changes of the influenza surface proteins, the HA and NA molecules. These changes can result in the appearance of pandemic viruses.

The first avian flu pandemic dates back to 1918 which resulted in the death of 40 million people, known in history as the ‘Spanish Flu’. Two other pandemics occurred in 1957 and 1968 from different strains of the avian flu virus. However, the recent H5N1 avian influenza virus first appeared in  Hong Kong in 1997 resulting in the death of six humans from 18 infected and the culling of more than one million poultry.

Until now, there have been sporadic incidents globally, mostly in  Asia, of avian flu outbreaks. However, with recent outbreaks outside the Asian borders, the World Health Organization believes that given enough time this strain of avian flu might evolve into another pandemic.

What Is Avian Flu?  

The H5N1 virus strain is just one out of 15 different subtypes of avian influenza, but until now, only two subtypes have been highly pathogenic causing major outbreaks; those being subtypes H5 and H7.

The H5N1 has not yet become a human influenza virus; it is a species-specific virus which has crossed the species barrier to infect humans in some cases.

According to the World Health Organization, the method of transmission from poultry to humans is by direct contact with infected poultry, or objects contaminated with their feces as well as exposure while slaughtering. Luckily, transmission from person to person contact has not been established significantly, thus the virus is not a human influenza virus as yet.

The avian virus’s current threat on human health consists of two main factors. One, when it is transmitted from poultry to humans it causes severe disease such as viral pneumonia and multi-organ failure which may be fatal. Two, if the virus is given a chance to mutate and evolve into a highly infectious form to humans, which is spread easily from person to person, this could result in a pandemic.