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Facts About...

Avian Influenza

What is it?

Avian influenza, or “bird flu”, is a contagious viral infection that can affect all species of birds. Domestic poultry flocks are especially vulnerable. Most strains of avian influenza cause mild illness in birds. Rarely, a severe strain appears that causes high rates of illness and death in birds. This is called “highly pathogenic avian influenza” and is of greater concern. The influenza A (H5N1) strain is a highly pathogenic strain, and was first reported to cause illness in humans in 1997. In 2003-2004 the H5N1 virus re-emerged and has since caused widespread illness in poultry and several hundred human cases with many human deaths in Asia, Europe and Africa.

How is it spread?

Avian influenza is found in bird droppings. Contaminated dust and soil may become airborne. Birds inhaling the airborne virus can become infected. Contaminated equipment, vehicles, feed, bodies of animals (e.g., rodents) can also spread the disease. Droppings from infected wild birds can contaminate commercial and backyard poultry flocks.

Human infection appears to be through direct and indirect contact/exposure to infected live or dead birds or contaminated environments. Research has shown that the risk of spread of H5N1 infection from birds to humans is greatest in persons having close contact with live, infected poultry. There is no evidence to-date indicating the virus can be spread to humans through properly prepared poultry or eggs. Spread of H5N1 from human-to-human is a rare occurrence.

What do I look for?

The avian influenza A/H5N1 strain has spread from birds to humans. In humans, the strain has caused severe illness and death. Initial symptoms include high fever, and other influenza-like symptoms. Diarrhea, vomiting, abdominal pain, chest pain, and bleeding from the nose and gums have also been reported as early symptoms in some patients.

What is the current situation?

The highly pathogenic influenza A/H5N1 virus has spread to Asia, Europe and Africa and has become entrenched in poultry in some countries. Scientists know that avian and human influenza viruses exchange genes when a person or animal (e.g., swine) is infected with viruses from both species. This swapping of genes can give rise to a completely new strain of the influenza virus that allows for efficient spread between humans and would be severe because humans would have no natural immunity.

Is there a vaccine effective against H5N1 in humans?

No vaccine is currently available to protect humans against disease caused by the H5N1 strain. Researchers are currently working with laboratories and leading vaccine manufacturers to develop an effective human vaccine.

How is it treated?

Oseltamivir, an antiviral drug, has been shown to reduce the duration of viral replication thereby increasing the chances of human survival. In suspect cases, oseltamivir should be prescribed as soon as possible, ideally within 48 hours of symptom onset, although administration of the drug should always be considered for patients presenting with illness at any time given the high mortality currently associated with H5N1 human infection.

How can I protect myself?

Travellers to affected countries are advised to avoid contact with live poultry, such as at markets where live chickens, ducks and pigs are sold. Travellers are also advised not to bring poultry and egg products from affected countries into Canada.
Travellers to affected countries should:

More information can be obtained from

Durham Region Health Department, Environmental Help Line 905-723-3818 or 1-888-777-9613

April 22, 2013