Current Situation
The outbreak of Highly Pathogenic Avian Influenza
virus (H5N1) affecting most of East Asia since late 2003 has recently
spread to areas in Eastern Europe, including Russia, Turkey, Romania
and Croatia. The virus is believed to have spread via migrating
waterfowl from affected regions in East Asia. At this point, the
outbreak in Europe has mostly affected wild birds and small backyard
operations with exposure to wild birds. No human cases have been
reported in Europe. The outbreak in Asia has so far claimed more
than 60 human lives, mostly in Viet Nam, Thailand and Indonesia.
Those affected have usually had close contact with infected poultry.
There is currently no clear evidence of human to human transmission,
and properly cooked poultry is safe to eat.
It is possible that migratory birds may introduce the H5N1 virus
to Canada. The Canadian Cooperative Wildlife Health Centre (CCWHC),
and the federal and provincial governments are undertaking a surveillance
project of wild waterfowl populations in Canada. Preliminary test results
have detected the presence of Avian Influenza (AI) virus, including
H5 subtypes, in migratory ducks. Further testing is being done to determine
if the H5 subtype found in Canadian wild birds is the H5N1 virus circulating
in East Asia. It is very unlikely that the virus found here is the same
H5N1 strain.
This supports previous research showing that AI
is common in wild waterfowl populations, and some of these strains
can be, or can develop into, highly pathogenic strains for poultry.
This underscores the importance of effective biosecurity in the
poultry industry at all times to avoid introducing a potentially
harmful pathogen to flocks.
H5N1 has also been detected in exotic pet birds
imported to the UK. The source of the infection has not been determined,
but the EU has banned all imports of live wild birds as a precaution.
The global trade in exotic birds, much of it illegal, poses a significant
risk for the spread of diseases such as AI. Veterinarians should
also be vigilant for signs of illness in exotic pet birds and submit
appropriate samples for diagnostic testing.
The incidence of the H3N2 Influenza A strain that has been
circulating in Ontario since early 2005 has been dropping. However,
new cases are still being reported in both swine and poultry, so
veterinarians and their clients should continue to practise strict
biosecurity, especially between swine and poultry holdings. Since
pigs can be infected with both animal and human influenza viruses,
mixing of the two viruses could occur in this species. For this
reason, it is important to minimize the exposure of pigs to all
influenza viruses, including human strains. In addition, pigs can
transmit influenza viruses to humans, who, if infected with human
influenza, may act as the "mixing vessel".
Poultry Biosecurity
If H5N1 were introduced to Ontario through wild birds,
the greatest risk would be to backyard flocks and to birds commingling
with, or exposed to, wild or migratory species. Nevertheless, there
are other routes by which this virus can be introduced, including people.
All poultry premises should have enhanced levels of biosecurity
to prevent the introduction and spread of Avian Influenza.
The risk of H5N1 notwithstanding, other influenza
strains and other diseases are a constant threat to Ontario poultry.
Anyone raising birds, including commercial poultry producers and
owners of backyard flocks, show birds and aviaries, should be familiar
with the appropriate biosecurity procedures and follow them on a
permanent basis. Resources and recommendations for enhanced
biosecurity are available on the OMAFRA web site listed below.
With respect to controlling the introduction and spread of influenza
viruses, the following recommendations are critical:
Public Health
With the spread of the virus to Europe, global
concerns about a human pandemic are growing. The H5N1 strain currently
poses a very low human health risk, except for those in close contact
with affected birds or their faeces. However, the more widespread
the virus, the greater is the risk of it mixing with a human strain
to form a more serious and easily transmissible influenza. For
this reason, the World Health Organization and Health Canada have
made several recommendations to reduce this risk, including vaccinating
poultry workers with the current human influenza vaccine.
All individuals working with livestock or poultry, especially
people working with birds, such as poultry producers and their employees,
veterinarians, abattoir workers and those handling wild birds, should
receive the annual human influenza immunization (available free
to all residents who work, live or attend school in Ontario). This
is not designed to protect these individuals from the H5N1 virus.
The risk to Ontario from this strain of influenza is extremely low.
Vaccination will reduce the possible mixing of human and avian influenza
strains, which would increase the risk of a potential pandemic strain
evolving.
In addition, individuals working with infected livestock
and poultry should follow strict infection control measures to prevent
exposure to influenza virus. These include frequent hand washing
and always washing hands after handling animals, and wearing appropriate
personal protective equipment such as mask, gloves, safety goggles,
coveralls, shoes/boots, and hair covers. Please contact your
local public health unit for more information.
If an individual develops influenza- like illness while working
with infected livestock, he or she should immediately seek medical
attention. Influenza is a reportable disease in Ontario and all
human influenza cases must be reported to the local Medical Officer
of Health.
Resources
The following resources provide more information
on Avian Influenza:
