Culling policy against highly pathogenic avian influenza

Authors: Suarez, David

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/26/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In February of 2022 the first detection of goose/Guangdong lineage, clade 2.3.4.4b of H5N1 highly pathogenic avian influenza (HPAI) was detected in the U.S. in wild ducks and shortly thereafter in commercial poultry. The initial viral gene segments were all European origin, but the virus began to reassort with North American lineage viruses in the polymerase genes, nucleoprotein, and non-structural genes to create multiple sublineages. Despite the different reassortant genotypes, all the viruses tested were highly pathogenic in chickens and turkeys, because the hemagglutinin gene is the primary virulence determinant. The HPAI virus has likely become endemic in wild birds, and it is continued to be an ongoing threat to the U.S poultry industry, with close to 100 million birds being affected by the outbreak. In the U.S., HPAI is a regulated disease with efforts to control and eradicate the virus in poultry. The U.S. has developed a robust veterinary diagnostic laboratory network, National Animal Health Laboratory Network (NAHLN), that with USDA oversight allows for the rapid and sensitive detection of poultry outbreaks. Each individual state has written protocols to respond to outbreak to rapidly depopulate infected flocks to prevent spread of virus from farm to farm. The USDA provides indemnity for the value of the birds at the time of diagnosis and supports the depopulation costs, safe disposal of birds, litter, and feed, and decontamination of the farm. Rapid response, often with 48 hours, after detection has reduced the amount of farm to farm spread of the virus, which is a major improvement over the 2014-2015 outbreak. The virus from each farm is sequenced to allow for in depth molecular epidemiology analysis. Because the virus is widespread in the wild bird population, the direct introduction of the virus to poultry continues to occur despite increased biosecurity efforts. Although the cost of the outbreak continues to mount, the depopulation control is continuing, but there is interest in vaccination as a control tool. At the current time, vaccinating poultry for HPAI will disrupt trade markets, and as a major exporting country the U.S. is only evaluating vaccines. Work to develop and validate a DIVA serologic surveillance strategy remains a high priority.