Bird flu information

The World Health Organization (WHO) has reported an outburst of a highly pathogenic avian influenza (HPAI) in birds affecting a number of countries in Asia, the Middle East, Europe and Africa. Bird influenza is a contagious viral infection that can influence all species of birds and occasionally causes disease in humans. Bird influenza viruses, of which there are 15 types, can infect wild bird populations, mainly water birds, typically without causing symptoms. The virus expands through bird faeces and contaminated water or dust. When bird influenza spreads to poultry or other birds, it can cause more serious disease. Outbreaks of bird influenza have been recognized in poultry flocks in most countries of the world for many years.

Types of bird flu

There are numerous types of avian influenza. The strains that cause the greatest number of deaths are called extremely pathogenic avian influenza (HPAI). The HPAI strain involved in the present outbreak is called H5N1. It was first recognized in 1997 in Hong Kong, where it caused poultry outbreaks and resulted into infections in 18 people with 6 deaths. Luckily, the outbreak was halted in Hong Kong at that time by strict control measures in the poultry industry. The strain of H5N1 that re-emerged in 2003 in a number of countries in Asia is a somewhat altered form of the 1997 virus. It has now spread to many parts of the world by migratory birds and probably through trade in poultry. Some countries have reported only isolated cases in wild birds while other countries have had extensive outbursts in poultry farms.

Effects of bird flu

Although the H5N1 virus can cause serious and sometimes fatal infections in humans, the actual number of human cases around the world has been small relative to the number of outbreaks in birds. Human cases have roughly all been in people who had close contact with infected poultry, usually from their own farms. There has been no proof of effective human-to-human spread of H5N1 infection, and so no evidence that a new influenza pandemic is starting. However, the Department of Health and Ageing is continuing to closely monitor the avian influenza situation.