AVIAN BIRD FLU
What is it?
Avian influenza (bird flu) is a highly contagious viral disease affecting the respiratory, digestive and/or nervous systems of many species of birds. It is caused by a Type A influenza virus. In its natural state, the virus has existed for millions of years as a harmless, intestinal infection of aquatic birds, such as ducks. But, on poultry farms, bird flu has become a lethal condition that is occuring around the world more frequently.
What is it?
Avian influenza (bird flu) is a highly contagious viral disease affecting the respiratory, digestive and/or nervous systems of many species of birds. It is caused by a Type A influenza virus. In its natural state, the virus has existed for millions of years as a harmless, intestinal infection of aquatic birds, such as ducks. But, on poultry farms, bird flu has become a lethal condition that is occuring around the world more frequently.
History
Avian influenza was first discovered among poultry in Italy in the 1870s. The H5N1 strain of highly pathogenic disease causing avian influenza, which became widespread in South East Asia in early 2004, has led to the destruction of hundreds of millions of birds, and has spread west through Europe and Africa.
Source
A New Scientist article indicated that drug resistant strains of H5N1 developed as a result of the widespread use by Chinese poultry farmers of the antiviral drug Amantadine. One of the largest outbreaks in the UK occurred at a Bernard Matthews farm in 2007, when 160,000 birds were gassed to death to try to prevent the disease from spreading. More than 2,000 of the company’s birds died in one week inside the overcrowded sheds. Despite the birds’ severe suffering, the first victims went unnoticed because the attrition rate in intensive poultry sheds is always so high. The industry acknowledges that some 100 viral, bacterial and musculo - skeletal conditions commonly affect commercial Poultry.
Source
A New Scientist article indicated that drug resistant strains of H5N1 developed as a result of the widespread use by Chinese poultry farmers of the antiviral drug Amantadine. One of the largest outbreaks in the UK occurred at a Bernard Matthews farm in 2007, when 160,000 birds were gassed to death to try to prevent the disease from spreading. More than 2,000 of the company’s birds died in one week inside the overcrowded sheds. Despite the birds’ severe suffering, the first victims went unnoticed because the attrition rate in intensive poultry sheds is always so high. The industry acknowledges that some 100 viral, bacterial and musculo - skeletal conditions commonly affect commercial Poultry.
Symptoms in animals
Birds shed the virus in their saliva, nasal secretions and faeces. The mild form of influenza produces symptoms, including respiratory problems, so inconspicuous that the outbreak may go unnoticed. The severe form may kill almost 100 per cent of infected birds within 48 hours. In 1997, a Hong Kong farmer described the severe symptoms of H5N1: ‘Their bodies began shaking as if they were suffocating and thick saliva started coming out of their mouths. The faces went dark green and black and then they died.’ Pathologists have found that the virus had reduced the birds’ internal organs to a bloody pulp.
Symptoms in People
Human victims have died of multiple organ failure. Their lungs filled with blood, their livers and kidneys became clogged with dead tissue and their brains swelled with fluid. The mortality rate is currently 60 per cent.
Routes of transmission
H5N1 can enter poultry sheds through supplies, cages, clothes, delivery vehicles, mammals and even insects. Equally, diseased material can just as easily leave such units. The H5N1 virus was first shown to have passed from birds to humans in 1997, during an outbreak among poultry in Hong Kong. The first possible case of human to human transmission was reported in Thailand in 2004.The disease cannot pass easily from one human to another, although recent research has shown that rapid mutation of the virus might make this easier in the future. People are most likely to pick up the bug through direct contact with secretions from infected birds, especially faeces. At the slaughterhouse, during removal of internal organs, the intestines are often ripped. A study found that 42 birds who followed a ripped carcass on the line were also cross - infected. A United States Department of Agriculture microbiologist said: ‘At the end of the line, the birds are no cleaner than if they had been dipped in the toilet.’