The Animal and Plant Health Inspection Service has confirmed that the H5N1 virus has been found in a dairy herd in Colorado, the ninth state so far, the state's department of agriculture said Friday.
The announcement came as APHIS issued guidance urging dairy and poultry producers to "redouble biosecurity efforts" and "be vigilant" about monitoring their herds and flocks for avian influenza.
CDA said that on Monday, April 22, it "received a notification of a dairy herd demonstrating clinical signs consistent with HPAI in cattle. Samples submitted to the Colorado State University Veterinary Diagnostic Laboratory tested presumptive positive for HPAI on April 24, and were confirmed by the USDA's National Veterinary Services Laboratory on April 25."
The department's press release did not say how the cows may have gotten the virus.
The APHIS guidance is supposed to explain in more detail an Animal and Plant Health Inspection Service order issued Wednesday that requires testing before the interstate movement of all lactating dairy cows as well as mandatory reporting of any positive H5N1 tests. The order goes into effect Monday.
APHIS said it will “reimburse for all interstate pre-movement testing” that is done at National Animal Health Laboratory Network labs. Sample collection or shipping is not covered by the government.
The guidance comes as federal officials attempt to stem the spread of the H5N1 virus, which has been found in 33 herds in eight states. The virus was confirmed in Texas in late March and spread to at least four other states – Michigan, Ohio, Idaho and North Carolina – through cattle shipped from Texas.
”Viral particles” were also found in samples from grocery stores, but federal officials and the dairy industry said that means pasteurization is working; others in the scientific community say the discovery highlights how little is know about how widespread the virus may be.
On Friday, FDA said it had received more results from "an initial limited set of geographically targeted samples as part of its national commercial milk sampling study underway in coordination with USDA." The preliminary results of the egg inoculation tests on quantitative polymerase chain reaction (qPCR)-positive retail milk samples "show that pasteurization is effective in inactivating HPAI," FDA said.
USDA has come under increasing criticism for what some infectious disease experts have said is a lack of scientific transparency and communication as the virus has appeared in each of the eight states. The dairy industry, however, has generally praised the response from APHIS.
Ted McKinney, president of the National Association of State Departments of Agriculture, told Agri-Pulse after the order came out Wednesday that although he had not spoken with each of his members, “I think most of them would say that the order was reasonable.”
He also said NASDA has been communicating well with APHIS since shortly after the first detection, and has done the same with the Food and Drug Administration’s Center for Veterinary Medicine.
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On the testing needed to allow interstate movement, McKinney said, “I suspect there will be some ramp-up issues.” But he expressed confidence that the NAHLN network can handle the volume, citing its experience with testing for highly pathogenic avian influenza in poultry.
APHIS's guidance encourages producers with positive herds “to collaborate with local and state public health agencies" by allowing access to farms.
“Human and animal health experts have a pressing need to better understand the spread of H5N1 and how the virus manifests and might impact both animal and human health,” APHIS says.
As to biosecurity, the document says, “While it is still unclear exactly how virus is spreading, the virus is shed in milk at high concentrations; therefore, anything that comes in contact with unpasteurized raw milk, spilled milk, etc. may spread the virus including other animals, vehicles, and other objects or materials.”
APHIS has identified at least one instance where the virus spread from dairy cattle to poultry “through an unknown route,” according to a FAQ dated April 24.
However, “analysis sequences of viruses found in cattle thus far have not found changes to the virus that would make it more transmissible to humans and between people,” the FAQ says.
The guidance says that “nonclinical” lactating dairy cattle – those not showing signs of having the virus, such as a sudden loss of appetite – that are going straight to slaughter don’t need a pre-movement test but will still have to have proper inspection documentation.
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