Bird Flu Alarm

Understanding Avian Influenza

Why people are worried about H5N1

Why people are worried about H5N1

Of the 15 avian influenza virus subtypes, H5N1 mutates rapidly and is good at acquiring new genes from viruses infecting other animal species. It is known to cause severe disease in humans. Birds that survive infection excrete virus for at least 10 days, orally and in faeces, so further spread is a great risk at live poultry markets and by migratory birds.

The epidemic of highly pathogenic avian influenza caused by H5N1, which began in mid-December 2003 in the Republic of Korea and is now being seen in other Asian countries. H5N1 variants demonstrated a capacity to directly infect humans in 1997, and have done so again in Viet Nam in January 2004. The spread of infection in birds increases the opportunities for direct infection of humans, with growing risks of a new world-wide flu epidemic if viruses mix in humans.

Several measures can help minimize the global public health risks that could arise from large outbreaks of highly pathogenic H5N1 avian influenza in birds. First - urgent need to halt further spread of epidemics in poultry populations, and reduce opportunities for human exposure to the virus. Vaccination of persons at high risk of exposure to infected poultry, using existing vaccines effective against currently circulating human influenza strains, can reduce risk of co-infection of humans with avian and influenza strains, and risk that genes will be exchanged. Workers involved in the culling of poultry flocks must be protected, by proper clothing and equipment, against infection. These workers should also receive antiviral drugs as a prevention measure.

When cases of avian influenza are seen in humans, information must be made available quickly. Thorough investigation of each case is also essential.