Department of Agriculture officials are encouraging monitoring and surveillance to mitigate the novel H1N1 virus' potential harm to U.S. swine herds.
But pork producers are submitting fewer influenza test samples to diagnostic laboratories, the chief veterinary officer for the USDA Animal and Plant Health Inspection Service said.
Dr. John R. Clifford, deputy administrator for Veterinary Services at USDA-APHIS, said Veterinary Services recently created guidelines on managing potential outbreaks of the virus in swine herds. They recommend surveillance for the virus, monitoring infected pigs through accredited veterinarians, and allowing producers to freely move animals to slaughterhouses, breeding facilities, shows, fairs, or other locations once they have recovered.
The USDA has also worked with agencies devoted to human medicine—such as the Centers for Disease Control and Prevention—to coordinate responses should an outbreak occur in humans and animals. And APHIS has been performing surveillance for the virus through a two-year, collaborative USDA-CDC pilot swine influenza surveillance program launched in September 2008.
The pilot surveillance program preceded identification of the novel H1N1 virus, and was built on the existing influenza surveillance system.
But Dr. Clifford said hog farmers have been submitting fewer diagnostic samples as "inappropriate trade restrictions" have decreased pork exports.
He thinks producers are worried positive test results will close markets for their pigs, even though the virus is not transmitted through meat. The USDA is working to improve consumer confidence in the safety of pork, and he hopes its efforts will encourage pig owners to submit more test samples to diagnostic laboratories.
"The number of samples being shared has fallen off dramatically," Dr. Clifford said. "And so we're trying to rebuild that confidence so that producers will start reporting and sharing these surveillance samples with us."
Ed C. Curlett, a spokesman for APHIS, said some state veterinarians have recently indicated producers are concerned government entities or private companies will not want meat from an infected herd, even after the animals recover.
Dr. Rodger G. Main, director of operations for the Iowa State University Veterinary Diagnostic Laboratory, said it is difficult to tell how much producers have decreased influenza testing, especially since this late August interview with JAVMA coincided with an off-season for influenza infections. But his laboratory is receiving substantially fewer samples than at the same time in previous years. He believes producers are reluctant to participate in the USDA's pandemic 2009 H1N1 influenza surveillance because of fear of the unknown consequences associated with a positive diagnosis.
"In the mind of the practitioner and producer, there's a lack of clarity in what will be the response to this virus being found in a pig herd," Dr. Main said.
Asked whether submissions could have decreased because of an overall decrease in respiratory tract diseases normally associated with diagnostic testing, Dr. Main said such a factor or economic conditions could be related to the decrease in specimen submissions. But, he said, pork producer apprehension is definitely affecting the flow of submission samples.
Dr. Liz Wagstrom, assistant vice president of science and technology for the National Pork Board, similarly cited producer concern as a cause for the decline in sample submissions. But, she said, the USDA guidance calls for moderate action, and she expects an opportunity to increase surveillance as pork producers learn about the plan.
"Producers can handle H1N1 very similarly to how they'd handle any other swine flu," Dr. Wagstrom said. "We don't normally move sick pigs."
Dr. David R. Schmitt, Iowa state veterinarian, agreed that producers are concerned their pigs will be the first to test positive for the novel H1N1 influenza virus. But he believes the cost of testing is also a factor in the reduction in sample submissions, as pork producers are not currently making money selling their swine.
"It's kind of tough for them to do a lot of additional testing," Dr. Schmitt said. "I believe there may be a two-factor situation there."
Dr. Wagstrom also said the cost of tests may be related to the drop in sample submissions. Pork producers are expected to lose $2.3 billion between the time the virus was discovered in late April and the end of the year, she said.
"We have producers who are going out of business," Dr. Wagstrom said. "We have producers who are really living on the edge of economic devastation."
But Dr. Wagstrom said a cool summer in the Midwest has helped pigs grow quickly, and market weights are high, so it is possible a decrease in respiratory tract disease overall is contributing to the decline in sample submissions.
Dr. Main said it is helpful that the USDA and the CDC and other public health organizations are working together to educate the public and stakeholders in animal agriculture, with the primary message being that pork is safe. He expects the USDA will continue providing guidance for veterinarians and producers to mitigate the impact and risks of transmission, should the pandemic virus enter U.S. pig populations.
Dr. Clifford noted that adequate surveillance will help keep vaccines and diagnostic tests current following mutation or recombination, which would be beneficial for both humans and animals.
"I think the importance of the practitioner in this is to encourage producers to help us report and do surveillance activities—or better development of diagnostics and vaccine production," Dr. Clifford said. "And with that, they should be aware that we're providing master seed virus to biological companies for the production of vaccine."
A vaccine will likely be available for pigs late this year, Dr. Clifford said.
Dr. Thomas J. Burkgren, the executive director of the American Association of Swine Veterinarians, said his organization has advocated, so far unsuccessfully, for swine veterinarians and pork producers—along with workers in human health care—to have priority in receiving the human-use vaccine against the virus.
"I think the importance of the practitioner in this is to encourage producers to help us report and do surveillance activities—or better development of diagnostics and vaccine production. And with that, they should be aware that we're providing master seed virus to biological companies for the production of vaccine."
—DR. JOHN R. CLIFFORD, DEPUTY ADMINISTRATOR, VETERINARY SERVICES,
ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE
The CDC Advisory Committee on Immunization Practices recommended July 29 that vaccination efforts first focus on pregnant women, people who live with or care for infants less than 6 months old, health care and emergency medical personnel, children and adults up to 24 years old, and people ages 25 to 64 who have chronic health disorders or compromised immune systems. Some of the target groups would be smaller in the case of a vaccine shortage.
Minimizing infections, mitigating impact
The USDA has held meetings with industry organizations, state public health authorities, and federal agencies such as the CDC to explain the department's guidelines on managing potential outbreaks of novel H1N1 influenza in animal populations, Curlett said.
"There's been broad agreement among these partners that the response is appropriate, and they've also acknowledged that swine surveillance is very important, too, so that we can learn more about (these) viruses," Curlett said.
Dr. Schmitt said Iowa has taken extra precautions to keep people from infecting pigs with the pandemic virus. It was recommended, for example, that the Iowa State Fair shorten the time for swine exhibitions over previous years. Sanitizing stations were added, people were reminded to wash their hands, and messages were broadcast for ill persons to stay away from the fair.
Pigs with certain signs of illness were tested for influenza, but none tested positive for the novel H1N1 virus.
Dr. Burkgren said the AASV has worked with the USDA on how to respond following infections, and he thinks it is a matter of when—not if—the novel H1N1 strain infects hogs in U.S. farms. Dr. Clifford said the USDA is concerned about transmission of the virus from humans to pigs.
"It's certainly a likelihood that you're going to get transmission of the virus from humans to pigs," Dr. Clifford said. "But we're certainly encouraging producers to practice the highest-level biosecurity, to keep people away from their pigs that may have flulike symptoms, and practice good personal hygiene."