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VDACS vet: Biosecurity ‘crucial’ to combat flu
By NANCY L. SMITH
PAINTER, Va. (July 28, 2015) — There may be no magic bullet to preventing the appearance of H5N2 highly pathogenic avian influenza on Delmarva, but Dr. Charles C. Broaddus, program manager with the Virginia Department of Agriculture and Consumer Services Office of Veterinary Services, has one imperative.
“Biosecurity is crucial. It is the most important thing we can do to prevent the introduction of this disease and to minimize the transfer of the disease to non-infected farms,” he said.
Dr. Broaddus has seen the disease up close and helped stop an outbreak in the Midwest earlier this year. His experience may be crucial to addressing HPAI if the deadly infection makes its way to the Eastern Shore. He related his experiences with infected poultry in the Midwest during a meeting of the bepartment’s Board of Agriculture and Consumer Services on July 20.
H5N2 HPAI struck chicken and turkey flocks in Minnesota in April. By May 3, a team from Virginia including Dr. Broaddus had responded to a request for assistance and were in Minnesota as USDA contractors.
During their two-week deployment, the team participated in poultry depopulations on 10 farms in Minnesota and Iowa. The chickens and turkeys, most of them sick and dying of the disease, were asphyxiated by a thick layer of foam applied to the flocks in the houses.
The foam, usually used for fire suppression, is “effective and approved as a humane method of depopulation,” Dr. Broaddus said.
The Minnesota infection affected 232 flocks, of which 211 were commercial; some 42.5 million chickens and 7.5 million turkeys died or were killed.
The source of the infection was believed to be wild waterfowl, which carry the pathogen but are not killed by it. Other possible sources include adequately disinfected equipment. Feathers or dust carried to the flock by the wind may also be the culprit, Dr. Broaddus said.
He said the virus can survive on boots or feathers a few days in cool wet weather.
He believes it is unlikely that the disease is transmitted through feed because the milling process gets hot enough to kill the pathogen.
Dr. Broaddus said turkeys can be infected with a lower dose and, in Minnesota, were affected “across the board.” A larger dose is required to affect chickens, he said adding that the disease predominantly affected layers, not broilers, in Minnesota. In the Midwest there have been few reports of infections of backyard flocks.
Affected poultry sickened “very profoundly, very quickly,” he said. “There have been no cases where humans have been affected. Proper cooking temperatures will kill the virus,” he said.
Dr. Broaddus reported on lessons learned from the Virginia team’s experience, including the need for training, preparation and planning before the virus affects Delmarva flocks. He said paperwork associated with the indemnification process can become a bottleneck, but that USDA appraisers are readily available.
Lessons from the depopulation include how to use and maintain the foaming device and the need for backup capability. He said that depopulation, which must be humane and prevent disease spread, is just one part of the disease management process and should be done within 24 hours of positive pathogen results. Timing “is critical to prevent disease spread,” he said. Other methods of depopulation should be considered, including ventilation shutdown, he added.
Another lesson is that a virus containment plan should be in place for each depopulation site. He said composting in the poultry house is an effective method. The heat of composting kills the virus and within 21 days with proper management, there will be nothing left but a few bones. He reported disposal is more difficult in layer operations; in Minnesota, the birds were killed with carbon monoxide, manually removed from cages and incinerated. He said the task was highly labor-intensive.
Another important lesson is the huge amount of supplies and people required to address an infection. He admitted it will be difficult to get enough people to handle an outbreak in Virginia and that states should ask for help as Minnesota did. He stressed the need for trained workers who are sensitive to the need for complete disinfection of equipment and protective clothing.
He emphasized the need for communication, collaboration, transparency and partnerships with frequent meetings between industry, state and USDA officials. Communication with the public also is needed, he said.
National Animal Health Laboratory Network capacity must be up to the challenges of an H5N2 outbreak. Dr. Broaddus said Virginia may go to a second shift to accommodate testing of samples.
“Biosecurity cannot be overemphasized,” he said, calling for elevated biosecurity now and, if the virus gets to the East Coast, “all measures possible should be taken.”
His list of lessons learned concluded with the need for flexibility in any plan to deal with HPAI.
With the fall migration coming, Dr. Broaddus said experts are planning for 500 infected premises nationwide. Virginia is preparing to respond to the first 10 infections in the state within seven days and expects USDA help within five to seven days.
When questioned about the possibility of a vaccination for the disease, he reported researchers are working on one. He cautioned, however, that U.S. trading partners could refuse to import meat from vaccinated poultry because the U. S. refused to import vaccinated poultry “for years and years.”
He said there are no plans to regulate backyard flocks, but in case of an infection, all poultry within a three to 10 kilometer zone around the infected premises must be tested.