Great Britain is experiencing an unprecedented outbreak of highly pathogenic avian influenza (AI), so what can poultry keepers do to prevent infection on their farms? Farmers Guardian reports.
The virus which causes AI is mainly spread through faeces from infected birds and Zoe Treharne, veterinary lead for the avian expert group at APHA, says most of the premises with infected birds during 2020-2021 were a result of direct or indirect contact between poultry and wild birds.
This means the mainstay of preventing infection is good biosecurity, and there are a range of measures that will help mitigate or prevent AI infection of poultry.
She says: “A nominated farm biosecurity champion can handle tailoring of on-farm measures and ensure that people follow procedures. They should routinely be on-farm to lead on good biosecurity behaviours.”
What to do if you suspect AI
Ms Treharne says if you suspect AI you must report it at once to APHA.
“Disease suspicion may be negated at three stages: over the phone due to history given; on a farm visit, due to clinical picture and history; or after negative test results. APHA will place restrictions on the farm while they investigate further.”
While there is nothing that can be done to save a flock with AI, Ms Treharne says there are measures that can be taken to protect a business.
“If staff move between farms, or there is shared equipment, an up-to-date legible visitor book may be one of your best assets. APHA can use this to assess the risk of people carrying the AI virus between locations.
“If a visitor book shows that there has been minimal movement in the time when infection was transmissible, this may enable other farms to run normally.”
To limit the spread of disease, Ms Treharne advises continuing and potentially increasing biosecurity on-farm.
And if initial testing returns negative for AI, Ms Treharne says farmers should ask their vet and the APHA case vet about further testing to investigate other possibilities for the disease picture on farm. She says: “Further investigations can be started as soon as possible if the other tests for HPAIV are negative.”
APHA advice for preventing disease
People
Only essential people should be on-farm, they should preferably not have direct or indirect contact with other birds. Recording last contact with birds in the visitor book can act as a prompt to assess the risk people may pose. Site- and house-specific coveralls, gloves and waterproof footwear should be available for everyone.
General farm
The farm should be clean and tidy to discourage rodents and wild birds. Wild birds should not be fed on the premises or nearby, and where possible, ponds should be netted. Feed spills should be quickly cleaned up and feed bins covered.Moss is attractive to wild birds and should be removed from roofs.
Flooding is a major risk factor for introduction of disease on-farm. If there are areas of the farm prone to flooding, or pooling water, prevention should be investigated.
Where possible, animal by-product bins should be at the edge of the farm boundaries, where they can be picked-up without the need to come on-farm.
Buildings, particularly poultry houses, should be proofed against wild bird entry, this may involve netting open areas, including ventilation. If netting is used to stop wild birds, the maximum mesh size should be 25mm.
Buildings should be regularly inspected for damage. Damaged roofs and blocked guttering can allow leaking of infected rainwater into poultry areas, and damaged buildings can allow wild bird and rodent access. Buildings should particularly be checked for damage after storms or other adverse weather.
Vermin control should be up to date and bait locations should be regularly checked and replenished or changed as needed. Keeping a written record helps show problem areas.
Vehicles and equipment
Farms should only allow essential vehicles on-site. All vehicles that come on-farm, should have their wheels and external surfaces cleaned and disinfected. It is vital that they are visibly clean before disinfecting, as dirt can stop the disinfectant working effectively. Farms can use a bucket and brush or a pressure washer for cleaning. A knapsack sprayer can make applying disinfectant easier and can help ensure an even and adequate spread. It is important that there is a nearby water supply to easily replenish the cleaning water and disinfectant.
The wheels and external surfaces of all equipment should be cleaned and disinfected before it enters a poultry area. [ZT1] This is regardless of if its farm specific or shared equipment.
Ideally sites should not share equipment.
Poultry house
If the poultry house is in good condition and leak free, the main way the AI virus will enter the house is on people or equipment. It is important to ensure anything entering the house is visibly clean and effectively disinfected.
A poultry house ideally has two areas; an atrium and the poultry area where the birds live. The atrium should be covered and is where house-specific footwear and clothing are kept. People should clean and disinfect footwear on entry to the atrium. Two boot dips are potentially necessary, one with water and detergent for cleaning, and the other with disinfectant. A hoof pick can be useful to remove mud from boot treads.
A step-over barrier is effective to demarcate where to change into house-specific shoes and overalls. A chair can help with boot changing at the step over barrier. Ideally, handwashing or hand sanitisation should occur before entering poultry areas.
Farms should keep bedding under cover in a bird proof area. Where possible bedding ought to be double wrapped. This enables the outer potentially infected wrap to be removed before it is brought into the house. The inner wrap should be disinfected alongside the equipment used to transfer it into the house. If the inner wrap is damaged, or there are signs of contamination, such as if the bedding is wet, then the bedding should not be used.
Disinfectant use
Disinfectant is an important part of biosecurity measures and it is vital that keepers use disinfectant correctly. [ZT2] Regularly refer to the manufacturer’s guidance on concentrations for poultry diseases, how often to change, how much needs to be applied and contact time. Keepers should change disinfectant if it is visibly dirty. Rainwater can dilute disinfectant, and UV light can deactivate disinfectant so if kept outside farms should cover and keep disinfectant within a solid-coloured container.
