USDA report highlights biosecurity risks on H5N1-infected dairy farms

Shared equipment and personnel among multiple dairy farms are major risk factors for the continued spread of highly pathogenic H5N1 avian influenza in dairy cows, the U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) said today in two new epidemiological reports.

One of the reports overview one based on survey results from affected dairy farmers, and the other Deep Dive Regarding the spread of infection among dairy cattle and poultry in Michigan, the state has been hit hardest by the spread of infection among dairy cattle, Now Number At least 94.

During a press conference today, Dr. Cammie Johnson, APHIS veterinary epidemiologist, said the multi-state epidemiological report provides a national clinical picture of the disease in cattle and how it is transmitted, and that the report from Michigan is an early snapshot of what is happening on the ground.

Both studies suggest there are three main drivers of transmission between farms: sharing of equipment and vehicles, sharing of personnel who can inadvertently carry the virus between farms on their clothing or boots, and movement of animals. “The bigger picture is that increased biosecurity is really important,” she said.

So far, genomic evidence continues to suggest a single introduction from wild birds, with further spread between dairy farms in the early weeks of the outbreak from Texas to Michigan, etc. The virus is now spreading between farms through multiple direct and indirect factors, according to the APHIS report.

The spread of infection between farms is driven by multiple factors

The survey revealed that more than 20% of farms admitted cattle within 30 days of the onset of clinical signs, and 60% of farms continued to remove cattle from the premises after animals showed signs of disease.

Most of the farms had cats, and of those, more than 50 percent had sick or dead cats. And more than 20 percent of the dairy farms also had chickens or poultry, and nearly all of those had sick or dead birds. USDA officials said cats were the canary in the coal mine, but other animals, such as cats and wild birds, likely did not play a large role in spreading the virus, but could act as vectors.

Clinically, dairy cows are most affected, with less than 10% of the herd showing signs of disease and mortality and culling rates averaging less than 2%.

The Michigan report, meanwhile, is based on data collected by an APHIS investigative team brought to the state by the Michigan Department of Agriculture and Rural Development to investigate possible links between infected dairy farms and virus spillovers at poultry farms. The report includes findings from 15 dairy farms and eight poultry producers.

About 20% of dairy workers and some of their family members worked on more than one dairy farm. About 7% of affected dairy workers also worked on poultry farms. In terms of equipment, about 62% of farms shared vehicles to transport cattle and only 12% cleaned their vehicles before use.

The farms were also frequently visited by visitors including veterinarians, feed consultants, contract hauliers, etc. Nearly all of the affected farms belonged to the same dairy cooperative and the dairy farmers all used the same deadstock hauler.

To date, circulating strains of B3.13 have not been found in migratory waterfowl in Michigan.

The report's authors praised Michigan dairy producers for their willingness to participate in the study, emphasizing that the findings have significantly increased knowledge about B3.13 in Michigan and across the nation. “Without them, this report would not have been completed.”

Questions remain about which states have new cases and the extent of the outbreak

At today's briefing, Johnson said it was too early to assess how H5N1 spread in the three most recent affected states of Iowa, Minnesota and Wyoming, adding that today's report paints a national picture of what is known about the spread so far and provides helpful context for understanding this event.

She said the discovery was a solemn reminder that farms already have the tools in place to control the spread of the virus: “Biosecurity is the key to prevention.”

Veterinarian Mark Lyons, who heads APHIS's Veterinary Services Ruminant Health Center, said it's still unclear if the infection is still spreading and that animal health officials are still trying to get a full picture of the situation, but he expects to find more cases.

As of yesterday, APHIS has recorded 94 outbreaks on dairy farms in 12 states. Yesterday, the Iowa Department of Agriculture and Land Stewardship reported the state's third dairy farm outbreak, this one affecting a second location in Sioux County.

Update on human research and vaccine production

Michigan Second case patient In the case of dairy workers who, unlike previous cases, were experiencing respiratory symptoms, Dr. Nirav Shah, principal deputy director of the Centers for Disease Control and Prevention (CDC), said the polymerase chain reaction cycle threshold was The (Ct) values ​​of the patient samples were high, suggesting low amounts of viral RNA in the samples.

This situation allowed CDC scientists to piece together large parts of the genome sequence, but made it difficult to generate a complete genome sequence, he said.

Shah said the findings were reassuring as so far there have been no changes that would suggest the virus that infected patients is more infectious, nor any changes in neuraminidase that would suggest it is less susceptible to the H5 vaccine or existing treatments.

Regarding the vaccine, Dr. David Boucher, director of infectious disease prevention and response at the Department of Health and Human Services' Office of Strategic Preparedness, said federal health officials plan to produce 4.8 million doses of the vaccine from bulk antigen over a three- to four-month schedule, with production set to begin in mid-July.

Other developments with H5N1:

• Minnesota has reported a new outbreak of the H5N1 virus in poultry, part of ongoing sporadic detections, with the latest reported outbreak occurring on a commercial turkey farm in Lyon County in the southwestern part of the state, housing 92,400 turkeys. APHIS Updates.
• The Minnesota Animal Health Commission today Announced Mandatory H5N1 testing for dairy cattle brought to shows. The measure will take effect on June 18 and will last until the end of 2024, unless the order is extended or rescinded before then.