Avian (Bird) Flu
The rapid spread of bird flu, which is not uncommon among chickens and other fowl, caught the attention of global health authorities in 2005. In October/November of that year, fowl on a B.C. farm tested positive for the H5 strain – which is not the deadly strain that caused deaths in Asia. As a precaution, the Canadian Food Inspection Agency (CFIA) ordered the cull of thousands of birds on that farm. There are at least 15 different types of avian influenza that routinely infect birds around the world. Human cases have been caused by a strain known as H5N1, which is highly contagious among birds and rapidly fatal. Unlike many other strains of avian influenza, it can be transmitted to humans, causing severe illness and death. If you work with live poultry, please follow any safety guidelines put in place by your employer.
Why the concern?
Influenza viruses are highly unstable and have the ability to mutate rapidly, potentially jumping from one animal species to another. Scientists fear the bird flu virus could evolve into a form that is easily spread between people, resulting in an extremely contagious and lethal disease. This could happen if someone already infected with the human flu virus catches the bird flu. The two viruses could recombine inside the victim’s body, producing a hybrid that could readily spread from person to person.
In rural areas, the virus is easily spread from farm to farm among domestic poultry through the feces of wild birds. The virus can survive for up to four days at 71 F (22 C) and more than 30 days at 32 F (0 C). If frozen, it can survive indefinitely.
In the most recent outbreak, human cases were from direct contact with infected chickens and their droppings. People who catch the virus from birds can pass it on to other humans, although the disease is generally milder in those who caught it from an infected person rather than from birds. If the virus mutates and combines with a human influenza virus, it could be spread through person-to-person transmission in the same way the ordinary human flu virus is spread.
An outbreak in 1997 in Hong Kong was the first time the virus had spread to people, but it was quickly contained. A total of 18 people were hospitalized with six reported deaths. About 1.5 million chickens were killed in an effort to remove the source of the virus. The 2004 and even more recent outbreak spread more rapidly to other countries, increasing its exposure to people in varied locations and raising the likelihood that the strain will combine with a human influenza virus.
Bird flu can cause a range of symptoms in humans. Some report fever, cough, sore throat and muscle aches. Others suffer from eye infections, pneumonia, acute respiratory distress and other severe and life-threatening complications.
Flu drugs exist that may be used both to prevent people from catching bird flu and to treat those who have it. The virus appears to be resistant to two older generic flu drugs, amantadine and rimantadine. The newer flu drugs, however, Tamiflu and Relenza are expected to work – though supplies could run out quickly if an outbreak occurs. Currently there is no vaccine, although scientists are working to develop one.
Rapid elimination of the H5N1 virus among infected birds and other animals is essential to preventing a major outbreak. The World Health Organization recommends that infected or exposed flocks of chickens and other birds be killed in order to help prevent further spread of the virus and reduce opportunities for human infection. The agency warns, however, that safety measures must be taken to prevent exposure to the virus among workers involved in culling.