Health orgs host HPAI call with latest details May 1 

(Journal photo by Kylene Scott.)

Representatives from the Food and Drug Administration, the Centers for Disease Control and Prevention and the U.S. Department of Agriculture joined media on an informational call May 1 to discuss the latest information on the highly pathogenic avian influenza cases in the U.S. dairy herd. 

Included on the call were Donald A. Prater, D.V.M., acting director of the Center for Food Safety and Applied Nutrition, FDA; Hilary Marston, M.D., M.P.H., chief medical officer, FDA; Demetre Daskalakis, MD, MPH, director of the National Center for Immunization and Respiratory Diseases, FDA; and Dr. Rosemary Sifford, deputy administrator veterinary services and chief veterinary officer, USDA. 

Sifford said the USDA has been handling the animal health aspect of the current situation with H5N1 in dairy cattle. As of the May 1 call, there are 36 affected herds across nine states, she said. 

“So far in our analysis some of the patterns that we’ve talked about before continue to hold true,” she said. “It appears that there is a single spillover event in the Texas panhandle geographic region from wild birds and to dairy cattle.” 

HPAI instigators

Wild birds are believed to be the initial source of the infection in dairy cattle, and subsequent cattle movements have spread the virus into other dairy herds and into poultry flocks.  

“Affected herds are still saying approximately 10% of their herds display symptoms, and those cattle that display symptoms generally returned to near their previous production levels after they recovered from the virus, which is taking around two weeks,” Sifford said.  

Most of the cows do recover with treatment, and little or no mortality has been experienced. 

“It is our top priority to continue to work through this emerging animal health issue,” she said. “We’re listening to what the science is telling us and working actively to learn more about the emergence of H5N1 in cattle.” 

USDA is continuing to engage with industry representatives, agricultural and health officials and producers to assess the best path forward.   

“We’re in regular close communications with FDA, CDC, the White House and state partners to make sure that we stay on top of the situation and that we’re relaying information on the epidemiology as well as bio-security measures and sharing important information between all of us,” she said. “Increased testing, surveillance and other measures are underway to protect animal and human health.” 

Federal order

A federal order was implemented April 29, and Sifford said there were a couple of key areas the order addresses.  

“The first is that it requires that all laboratories and state veterinarians report to USDA any livestock that test positive for avian influenza or any type of influenza A,” she said. “This is important for us to be able to identify all positive tests that might be run and be able to follow up on those appropriately.” 

The other focus was on restricting movement of lactating dairy cattle and requiring them to have a negative test for avian influenza or influenza A before being allowed to move. 

“No dairy cattle that test positive for avian influenza can move interstate without following conditions that we specify,” Sifford said. “And then producers that do have positive tests in this protocol must be a part of our epidemiological investigation and movement tracing so that we are able to follow up on those herds and identify any potentially other affected herds.” 

Requiring positive test reporting and pre-movement testing will help USDA better understand where the disease is present and be able to follow up appropriately, she said.  

“We are committed to continuing to work closely with our partners and taking steps to contain the virus based on our evolving understanding of the science and risk profiles,” she said. 


Prater said sound science is critical to informing public health when it comes to food safety.  

“We take this matter and the safety of the milk supply very seriously, given the detection of H5N1 in dairy cows is a novel and evolving situation,” he said. 

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Until recently there were no studies done on the effects of pasteurization on HPAI viruses and bovine milk.  

“U.S. federal partners have been hard at work quickly setting up these first of their kind studies, and we’re encouraged that initial gold standard inoculation tests show that pasteurization is effective and inactivating the HPAI virus,” Prater said.  

Initial testing results from the national retail milk study found that about one in five retail milk samples have tested positive for HPAI viral fragments. Test results were shared as soon as FDA was informed.  

Upon further testing on a second group of samples of pasteurized retail dairy products, including cottage cheese and sour cream, as well as fluid milk, “We were encouraged that this preliminary testing also did not detect any viable virus,” he said. 

To ensure the safety of milk derived products for the youngest population, FDA also tested samples of retail powdered infant formula and powdered milk products marketed as toddler formula.  

“PCR results of formula testing were negative, indicating no detection of viral fragments in powder formula products, so no further testing was required for these things,” Prater said. “These additional preliminary results further affirm the safety of the U.S. commercial milk supply.” 

Prater said the FDA is continuing to locate and identify additional products for testing. Samples of pooled raw milk that has been routed to pasteurization and processing for commercial use will continue to be tested.  

“This will be used as a basis to characterize potential virus levels that pasteurization may encounter and will be used to inform our studies to further validate pasteurization,” he said. “These important efforts are ongoing, and we’re committed to sharing additional testing results as soon as possible.” 

As the situation continues to evolve, FDA is committed to continued surveillance of milk production and processing and pasteurization to help ensure the safety of the milk supply, Prater said.  

“Our state partners are integral to this process, and we’re working with them on a continual basis,” he said. “We’ll also continue working with our state co-regulators on managing this emerging disease.” 

FDA strongly advises against the consumption of raw milk that has not been pasteurized and recommends the industry does not manufacture or sell raw milk or raw milk products made with milk from cows showing symptoms of illness, including those infected with avian influenza viruses or exposed to those infected with avian influenza viruses.  

“We know that assessments can change as we learn more, and we’ll be transparent about any changes based on emerging data,” Prater said. “We recognize the importance of releasing further actionable information.” 


According to Daskalakis, the CDC is monitoring flu surveillance data, especially in areas where H5N1 viruses have been detected in dairy cattle or other animals, for any unusual trends in flu-like illness, flu or conjunctivitis.  

“CDC flu surveillance systems at this time show no indicators of unusual flu activity in people, and that includes avian influenza,” he said. “This data is being shared on the CDC website.” 

The center also supports the monitoring of exposed workers by working with USDA and state groups. 

“People who have been exposed (by) poultry or other animals are monitored for 10 days after exposure,” he said. “Those who show symptoms are subsequently tested for novel influenza A and seasonal flu viruses as well as other respiratory viruses.” 

CDC does confirmatory testing when needed and is engaged with public health partner organizations to share information and ensure preparedness for any potential human infection. CDC also provides guidance and recommendations. 

“We’ve developed guidance for various groups, including recently updated interim recommendations for worker protection expanded to include people who work at slaughterhouses,” he said. “CDC has also developed a graphic for recommending personal protective equipment for people who work with farm animals.” 

CDC is continuing its ongoing assessment of the risks posed by these viruses, including conducting additional laboratory work to further characterize current H5N1 viruses. 

“The flu viruses are constantly changing,” Daskalakis said, adding that CDC continually analyzes viruses to identify genetic changes, including those that could allow it to spread more easily between people or cause serious illness.  

CDC is also conducting testing for susceptibility and recommended flu antiviral medication.  

“Remember, this medication can be used for treatment and is recommended for prevention in people with exposure,” he said. 

CDC is also looking at antiviral resistance properties of more than 200 publicly posted H5N1 viral sequences from cattle.  

 “We are working to grow H5N1 virus stock from the one human case in Texas to use for additional laboratory experiments to learn how the virus reproduces and goes to human and cow respiratory tract epithelial cells, as well as cow mammary epithelial cells and to assess the severity of illness and transmissibility of the virus under different scenarios,” Daskalakis said. 

Finally, CDC is doing outreach and education in multiple domains, Daskalakis said.  

“CDC is conducting broad outreach to the public to raise awareness about the current situation and remind everyone that the current risk to the general public health is low,” he said, “because there are certain groups of people who are at greater risk.” 

For more information about H5N1 in livestock visit

Kylene Scott can be reached at 620-227-1804 or [email protected].