Eric Gonder – February 26, 2023

Highly pathogenic avian influenza (HPAI) is present almost worldwide and is becoming endemic in wild birds. The commercial poultry industry needs a long-term approach to a continuing disease situation – similar to those in primary breeders.

This will require increased capital expense, careful design and a more comprehensive approach than conventional operational biosecurity.

Changes Needed
To protect poultry when HPAI was not endemic, we relied on operational biosecurity, which involves safely getting everything poultry needs on and off farms and in and out of buildings without bringing in disease.

This usually meant training employees to move themselves and equipment securely in and out of houses with clothing and footwear changes, disinfecting equipment on entry and establishing farm perimeters. It is a quick response, usually requiring training, minor physical changes and a small amount of capital expense.

To decide what needs to change, we must ask how the risks have changed with more species of wild birds affected and possibly other animals carrying HPAI consistently rather than seasonally.
Turkeys are at higher risk since a lower dose of the virus is needed to infect them.

Lessons Learned
Considering the types of flocks most affected in the current North American epiornithic, some general observations can be made:

1. Longer-lived poultry, including breeders, turkeys, and table-egg-laying chickens, are at higher risk. Short-lived meat chickens are at lower risk. The longer the birds live, the greater the chance HPAI will be introduced to that flock.
2. Farms with more poultry houses are at higher risk of virus introduction within the farm perimeter. The larger the farm area, the greater the chance wild birds will deposit virus on the farm.
3. Farms with more birds per house are at higher risk due to increased personnel and equipment entry frequency.
4. Poultry requiring personnel and equipment to enter houses more frequently are at higher risk. More trips in and out of the home increase the chance of the virus being brought in.
5. Poultry exposed to natural ventilation or high-velocity ventilation systems are at higher risk. Aerosol transmission risks are higher. Natural ventilation is the highest risk, but unscreened inlets and entrances increase potential exposure to insects and other vectors. Areas with wind-borne dust transmission between farms are at higher risk.
6. Farms with high labour requirements are at higher risk due to the increased risk of personnel turnover and the need for contract employees. Both issues require increased attention to training and designing biosecurity procedures to be as easy and foolproof as possible.
7. Farms attracting feral birds are at higher risk, including those in migratory flyways, near-standing water, with attractive nesting and resting sites or other attractants. The more wild birds visit a farm, the greater chance that HPAI will be introduced.
8. Turkeys are at higher risk since a lower dose of the virus is required to infect them.

Potential Solutions
What can be done to reduce these long-term risks?

1. Recognize turkeys, breeders, table-egg laying chickens, large farms, and large houses need increased protection. Plan capital expenditures, labour requirements and other needs accordingly.
2. Reduce the need for people and equipment to enter houses by utilizing as much as possible remote monitoring, automated equipment, and robotics.
3. Keep farm and house sizes as small as is practical.
4. Design farms and houses to eliminate feral bird and animal attractants and maintain them properly. Remove or protect standing water sources and screen potential nesting and perching areas.
5. Design ventilation systems to accommodate biofilters and reduce aerosol dispersion from exhaust ventilation. Directing fan outflow downwards reduces the aerosol distribution of potentially contaminated dust. Biofilters at ventilation inlets require increased fan capacities.
6. Plan new construction as far from other poultry as possible. The risk is increased if there are more farms in a small area.
7. Work with vendors and suppliers to design equipment and facilities that are easy to clean and disinfect.
8. Provide supervisors and managers with the time to train and supervise employees and contractors. Inspect all biosecurity procedures on both a regular and unannounced basis.
9. Planting trees or shrubs can reduce wind velocity and dust transmission in areas with potential dust transmission between farms.
10. Design or modify houses to create entrances for only clean personnel and equipment and exits for potentially contaminated personnel and equipment to reduce the potential for cross-contamination and the chances of operational biosecurity errors.

Everyone needs to recognize that every surface outside the poultry house can be contaminated with the influenza virus and that everything that comes in contact with anything outside the home can bring the virus inside. That includes personnel, equipment, feral birds, other animals, insects, and possibly contaminated air under the right conditions.

Recognize that things have changed. Think, be innovative and plan for this long-term risk. The changes that need to be made will also reduce other disease risks.

https://www.wattagnet.com/poultry-meat/diseases-health/avian-health/article/15537536/rethinking-poultry-farm-biosecurity-in-response-to-hpai