Avian influenza in domestic birds

Description

Avian influenza (AI), sometimes called ‘avian flu’, is a contagious viral disease that affects many domestic and wild bird species.

The term ‘pathogenicity’ is commonly used when discussing avian influenza. The term refers to the severity of disease caused in poultry.

There are many strains of AI virus, generally classified into 2 categories:

• low pathogenic (LPAI) strains typically cause few or no clinical signs in poultry, and may go undetected due to a lack of disease in some species of birds
• highly pathogenic (HPAI) strains can cause severe clinical signs and potentially high mortality rates among poultry

While AI has been detected in wild waterfowl for many years, its first reported outbreak in Canadian domestic poultry was in 2004 in British Columbia.

Types of avian flu virus

Influenza A viruses are labelled based on 2 surface proteins: hemagglutinin (H) and neuraminidase (N), for example, H5N1, H7N3. At least 16 hemagglutinins (H1 to H16) and 9 neuraminidases (N1 to N9) subtypes have been found in influenza viruses from birds.

Only H5 and H7 subtypes have demonstrated an ability to mutate from a low pathogenic form to a highly pathogenic form in poultry. As a result, all H5 and H7 strains of the avian flu virus are federally reportable in Canada under the Health of Animals Act, whether or not they are highly pathogenic.

Avian influenza is a concern

Outbreaks for AI can lead to devastating consequences for the poultry industry both at the farm level as well as at the national level:

• farmers might experience a high level of mortality in their flocks
• to contain outbreaks, healthy birds often need to be culled and disposed of
• job stability and food security are threatened, especially in developing nations

The presence of HPAI restricts international trade of live birds and poultry products.

Public opinion may be damaged, reducing both travel and tourism in affected areas.

Certain strains of AI are zoonotic (have the potential to infect humans). Transmission to humans has occurred when there is close contact with infected birds or heavily contaminated environments.

More information about avian flu and human health can be found on the Government of Alberta – Influenza web page.

How to report

Avian influenza is both a provincially reportable disease for domestic birds under Alberta’s Animal Health Act and requires immediate action to control or eradicate it. In wild birds, it is a provincially notifiable disease.

All suspected or confirmed cases must be reported to the Office of the Chief Provincial Veterinarian (OCPV) within 24 hours:

Hours: 8:15 am to 4:30 pm (open Monday to Friday, closed statutory holidays)
Phone: 780-427-3448
Toll free: 310-0000 before the phone number (in Alberta)
Fax: 780-415-0810

Outbreaks in domestic poultry should be reported both federally, to the Canadian Food Inspection Agency (CFIA) and provincially, to the Office of the Chief Provincial Veterinarian (OCPV).

The OCPV should also be notified if avian influenza is found in wild birds in the province for additional monitoring, detection and prevention.

Clinical signs

Different degrees of illness occur in birds because of the different strains and pathogenicity (severity) of AI. Birds may not always show signs of disease.

Clinical signs in poultry can vary widely and include the following:

• no signs of disease at all and quick recovery from the infection
• depression and droopiness, and/or loss of appetite
• sudden drop in egg production, with many of the eggs soft-shelled
• purplish-blue colouring of wattles and combs, with blisters on the combs
• swelling of the skin under the eyes
• coughing, sneezing
• diarrhea
• nervous signs, such as a lack of co-ordination and an inability to stand or walk
• a few deaths over several days in the flock, followed by a surge in mortality that can reach up to 100% in 48 hours

Clinical signs can vary, so it’s better to be cautious and report any birds that might be sick.

Where it’s found

More information on the responses to the events listed below is available on the CFIA – Flocks infected with Avian Influenza in Canada web page:

• In 1966, a case of high pathogenic AI was identified in Ontario.
• In 2004, an outbreak of high pathogenic avian flu (H7N3) in British Columbia resulted in the destruction of millions of domestic poultry, at an estimated cost of $300 million.
• In 2005, detection of low pathogenic avian flu (H5N2) in British Columbia resulted in the depopulation of poultry on a single farm.
• In 2007, a single poultry farm in Saskatchewan was infected with high pathogenic avian flu (H7N3) and was depopulated to prevent spread of the disease.
• Since that time, low pathogenic avian flu was isolated in British Columbia in 2009 (H5N2) and in Manitoba in 2010 (H5N2). Both cases resulted in depopulation.
• In December 2014, high pathogenic avian flu (H5N2) was identified in British Columbia and Ontario on several poultry farms.
• A confirmed case of AI in was reported in 2016 at a commercial duck farm in Ontario.
• In 2022, several cases of avian influenza have been found across Canada. The investigation and response is ongoing.

A number of different strains of avian flu virus are known to exist in wild birds across Canada.

• Avian Influenza in wild birds

How it spreads

AI is spread from infected birds to susceptible birds. Migratory waterfowl can be carriers of AI viruses. Outbreaks in domestic poultry occur when AI viruses enter the flock either by direct contact between wild waterfowl and poultry or by human activities that allow the virus into the barn/coop.

The avian flu virus is highly concentrated in feces and in nasal and eye discharges. It can also be found in feed, water and surfaces contaminated with infected feces.

Indirect transmission may also occur via contamination of:

• poultry products
• vehicles, tools and equipment
• egg flats and cases
• clothing and footwear
• rodents
• farm dogs and cats
• biting insects

What you can do

Producers can help prevent the spread of avian flu through strict biosecurity and early detection. It is impossible to prevent the entry of all avian flu viruses into Canada because of the presence of the virus in wild birds, especially waterfowl. However, the implementation of an effective avian biosecurity plan by producers is essential in protecting domestic poultry from AI.

Early detection

Producers and veterinarians must be familiar with the clinical signs of the disease to detect avian flu early. Early detection helps ensure a quick response – which, in turn, helps minimize the spread of the virus and the economic damage to the industry.

Vaccines

There are poultry vaccines for some strains of avian flu, but these vaccines do not necessarily provide protection for the many strains that exist.

• Since there is no way of predicting which strain of the avian flu virus will infect a flock, vaccination is not recommended as a preventative measure.
• Vaccination may be used in the face of an outbreak where the strain of the virus has been identified, but this is a decision made on a case-by-case basis.

Other precautions

Producers can take the following steps to prevent the spread of avian flu in poultry:

• Prevent contact between domestic poultry and wild birds.
• Discourage the presence of wild birds in dugouts and ponds. If dugouts are being used as a source of drinking water, treat the water to kill the virus.
• Control access to poultry houses and facilities by people and equipment.
• Make sure poultry equipment is clean and disinfected before it is used, especially if it was used on another farm.
• Change into barn-dedicated footwear or clean and disinfect footwear prior to entering poultry areas.
• Commercial producers: establish all-in all out flocks with no introduction of new birds to existing flocks.
• Non-commercial and hobby poultry owners: quarantine any new birds for at least 21 days in a separate area prior to adding them to the existing flock.

Control and monitoring

The control and eradication of outbreaks of H5/H7 avian flu viruses is led by the CFIA with additional support available from the provinces. For more information about the control of avian influenza, see CFIA – Notifiable Avian Influenza.

Monitoring

Avian flu viruses have been monitored in North America for over 30 years.

In Alberta, monitoring is done in commercial poultry and backyard flocks by testing dead birds that may have the virus. Working with the Canadian Wildlife Health Cooperative, the Alberta government tests for avian flu in dead wild birds in Alberta.

Response plans

Governments and industry work together to plan and prepare for the possibility of an outbreak of a disease like AI in the poultry industry. There are programs and projects in place to prevent and address avian flu.

Comprehensive emergency response plans are in place in conjunction with national surveillance programs that outline actions to be taken, if AI were to be detected in Alberta poultry.

The plans were developed together with the CFIA, the poultry industry, Alberta Health, and Alberta Environment and Protected Areas.

Exercises are conducted regularly to test the response plans.

Containment lab

The Alberta government's Containment Level 3 laboratory, completed in 2006, allows Alberta to conduct advanced work with livestock diseases such as avian influenza. The lab:

• operates as part of a national laboratory network that provides diagnostic testing for foreign animal diseases
• provides regional avian flu diagnostic testing for Alberta, northern British Columbia and the Canadian territories

Publications

• Avian influenza and small-flock poultry (fact sheet)

Contact

Connect with the Office of the Chief Provincial Veterinarian:

Phone: 780-427-3448
Toll free: 310-0000 before the phone number (in Alberta)
Fax: 780-415-0810