Lock up your chickens before plague comes home to roost

While many people concerned with the ethical treatment of farm animals prefer to purchase eggs laid by free-range hens, the keeping of poultry indoors could protect us from consuming harmful substances, e.g., dioxins, passed on to us in the eggs and meat from hens and chickens allowed to forage freely on contaminated soil. But it could also protect the hens and us from contracting fatal diseases spread by migratory wild birds arriving on our shores from Asia.

The avian influenza or "bird flu" epidemic has been recognised by leading health professionals and politicians as a grave global threat to public health and the world economy that requires bold global solutions. Prime Minister Howard, while attending the recently concluded UN 2005 Summit, where these matters were discussed, announced that Australia is joining the new International Partnership on Avian and Pandemic Influenza (IPAPI) and that we are stepping up our influenza and pandemic planning and response measures.

There is good reason to be concerned. A particularly infectious strain of the bird flu, Avian Influenza A (H5N1) virus, infecting many wild birds, has been found to be very contagious in domesticated birds, including chickens and ducks, and to kill them. This is a real threat to poultry industries worldwide. However, this strain is also infectious to humans that come in direct contact with diseased poultry. The most worrying discovery is that of the 120 people infected with the H5N1 virus strain, 50 per cent died. In comparison, the SARS-associated coronavirus that caused the 2003 global outbreak with 8000 people being hospitalised with severe infections of their respiratory tract killed less than 10 per cent of the people who contracted the disease.

The worst case scenario for the avian flu virus is that it mutates again and becomes airborne, leading to a global pandemic like the 1918 flu epidemic that killed 20 million people and affected 20 per cent of the world’s population to some extent. This extinct killer strain of influenza was described last year after some high technology molecular detective work: intact DNA of the extinct influenza virus, preserved by the permafrost of her burial ground, was isolated from lung tissue of an Inuit woman in Canada . The genes of the influenza strain isolated from her lungs were found to be of an avian origin but a critical gene of this strain had mutated to make the virus strain deadly to humans (Science. 2004 Mar 19;303(5665):1838-42).

The chance for the H5N1 strain mutating and becoming airborne increases every time it passes through another domestic bird or a human.
 
The recently reported flu epidemic among wild birds and poultry in Russia has been attributed to migratory wild geese sharing feed and water supplies with free-range poultry (news.bbc.co.uk/1/hi/world/europe/4182746.stm). This is a concern since it means that the virus has effectively taken to the air and is winging it across the globe, carried not by the jumbo jet that spread the SARS virus from South East Asia to Canada, but by infected migratory birds that don’t pass through any quarantine and customs control.

In response to this threat to the poultry industry and public health, farmers in Holland have recently been ordered by their government to keep all poultry indoors, thus in effect banning the production of free-range eggs (news.bbc.co.uk/1/hi/world/europe/4172182.stm). Germany and other EU countries are considering similar measures.

Migratory birds are heading our way downunder after spending a hectic few months breeding and feeding their offspring in Siberia and South East Asia.

Australian state governments, in conjunction with the poultry industry, have stepped up their surveillance for the disease. In June, at a recent International Biotechnology Conference in Philadelphia researchers from the Victorian Department of Primary Industries described the development of a DNA test for bird influenza that cuts down the time for a result from three weeks to one day. Time is of the essence in preventing a large outbreak of a very contagious bird disease that could devastate our poultry industry.

However, to my knowledge no Australian government has considered following the proactive example set by European countries of banning chickens and hens from roaming around in the open. If there was an outbreak of avian flu among our free-range poultry due to infection spread by wild migratory birds, it is likely that they would have to be put down in their millions to prevent the further spread of the virus, as happened in Asian countries during recent outbreaks.

The more sinister side to the "bird flu", of course, being the increased risk for the avian virus to mutate and become airborne, potentially creating a pandemic more deadly than the 1918 killer flu.

It is time for Australians and Australian governments to carefully consider the potential unintended impact that "ethical" farming practices could have on the poultry industry, but more importantly on public health in light of the scientific evidence which underscores the grave threat posed by this spreading bird flu epidemic.