Avian Influenza

What is it?

It is a contagious disease of animals caused by viruses that normally infect only birds and less commonly pigs.  While all birds are susceptible to infection, domestic poultry flocks are especially vulnerable to infections that can rapidly reach epidemic proportions.
2 forms: mild – ruffled feathers or reduced egg production
Fatal – “highly pathogenic avian influenza” first recognised in Italy in 1878, is extremely contagious in birds and rapidly fatal, with mortality approaching 100%. Birds can die on the same day that symptoms first appear – the highly pathogenic H5N1 avian influenza infection is obviously the current concern.
It affects most species of bird but very rarely do Ducks and Geese contract the disease although they can carry the virus.

Spread:

The disease is mechanically transmitted through the movement of live and dead birds, vehicles, equipment and personnel travelling between farms, markets, abattoir, insects and rodents and migrating waterfowl.  Infected birds spread the virus through faecal and nasal discharges.
Disease spread from country to country is through international trade in live poultry.  Migrating birds including waterfowl, sea birds, shore birds  can carry the virus for long distances, waterfowl most notably ducks are the natural reservoir of bird flu viruses, and these birds are the most resistant to infection.  They can carry the virus over great distances, and excrete it in their droppings, yet only develop mild and short-lived symptoms,
(Domestic ducks and geese however are susceptible to lethal infections).

Symptoms vary but include:

Ruffled feathers
Soft-shelled eggs
Depression and droopiness?
Sudden drop in egg production
Loss of appetite
Purple/blue colouring (cyanosis) of wattles and comb
Green diarrhoea
Blood tinged discharge from nostrils
Loss of ability to walk and stand
Pin-point haemorrhages (feet and shanks)
Respiratory distress
Sudden death

What bio security disease control measures should be implemented?

Reduce all vehicle and visitor movement on and off site
Clean and disinfect all vehicles and equipment entering and leaving the site
Provide shower facilities
Use disinfectant foot baths at all entry and exit points replenish at least every 4 days.
Exclude wild birds from poultry houses/barns or contact with commercial stock
Clean up all feed spillages under feed bins to discourage wild birds and rodents.
Avoid standing water and do not use surface water which may be faecally contaminated by wild birds as a source of drinking water

What measures should be undertaken to control the spread of avian influenza from an infected farm site?

The most important control measure for an infected farm site is rapid destruction (culling or stamping out) of all infected or exposed birds, proper disposal of carcasses, and the quarantining and rigorous decontamination of farms.

Disinfectant:

Must have been independently tested and DEFRA approved to be used:
Antec Virkon S approved at 1:320 but Antec recommend 1:100 (as a safeguard against the challenge of mud and muck if not pre-cleaned and certainly for foot and wheel dips where rain can further dilute).
Antec Farm Fluid S (discontinued) also approved at 1:320  but use at 1:100
Antec Longlife approved at 1:250 but use at 1:100
Diversey Zal Perax – boot and wheel dips, interior and exterior area disinfection
Approved at 1:145
Provita Virucidal Extra is a new disinfectant approved at 1:300
The on farm factors apply to ALL DISINFECTANTS and for that reason it would be best to use all disinfectants at 1:100 rate!

Routine:

Thoroughly dry clean removing bedding and litter etc then wash all surfaces with heavy duty detergent, rinse with clean water at high pressure and then apply an independently tested and approved disinfectant.

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