The USDA has approved ventilation shutdown as an emergency depopulation method to be used in flocks that have been affected by avian influenza.

The agency on September 18 released documents that explain using ventilation shutdown as a means to depopulate in a suspected case of avian influenza. USDA’s Animal and Plant Health Inspection Service (APHIS), veterinary officials from various states, and poultry industry stakeholders had been studying the use of ventilation shutdown, because a need to expedite the depopulation process had been identified.

The most effective and commonly used depopulation methods had been through use of carbon dioxide and water-based foam. However, at the height of outbreak detections, APHIS stated that the existing methods were insufficient for rapid depopulation and disposal. The longer the depopulation process takes, the greater the risk for the spread of the virus, the agency stated.

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According to the APHIS documents, carbon dioxide and water-based foam methods will continue to be the primary methods first considered in an avian influenza response, but if these methods will not achieve depopulation of infected flocks within 24 hours, ventilation shutdown may be considered. However, ventilation shutdown should only be used after a full consideration of the epidemiologic threat posed concludes that no other method can achieve a sufficiently timely measure of assurance that the virus won’t spread.

Further, ventilation shutdown can only be used to depopulate flocks if agreed upon by APHIS officials, state or tribal officials and the incident management team and national incident coordinator.