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Highly Pathogenic Avian Influenza (HPAI)

May 2, 2024

Highly Pathogenic Avian Influenza (HPAI)

Background

Highly pathogenic avian influenza (HPAI) is a disease that is highly contagious and often deadly in poultry, caused by highly pathogenic avian influenza A (H5) and A (H7) viruses; it is also known as bird or avian flu. HPAI viruses can be transmitted by wild birds to domestic poultry and other bird and animal species. Although bird flu viruses do not normally infect humans, sporadic human infections have occurred. It is important to note that “highly pathogenic” refers to severe impact in birds, not necessarily in humans. HPAI has been detected in livestock in multiple states.

To date, HPAI has not been detected in Oregon livestock. 

The strain of HPAI detected in livestock is the same strain (H5N1) that has been circulating in wild waterfowl throughout the US. Initial testing of this virus has not found any mammalian adaptations that would make it more transmissible to humans. While cases among humans in direct contact with infected anima​ls are possible, the risk to the public remains low. This continues to be a developing situation and more information will be shared by federal and state partners as it becomes available.

Testing Required for Interstate Movement of Cattle

The United States Department of Agriculture (USDA) announced a federal movement order in response to the ongoing outbreak of HPAI in dairy cattle. The federal order requires pre-movement testing of all lactating dairy cattle, prior to interstate movement. 

Emergency Import Requirements

The Oregon Department of Agriculture (ODA) enacted emergency import requirements for cattle being imported into the State of Oregon from any state with cattle currently affected by HPAI/BIAV. In addition to existing import requirements, these emergency import requirements include:

  • No cattle exposed to, infected with, or suspected to be carrying HPAI/BIAV may be imported into Oregon. 
  • Non-lactating dairy cattle require:
    • A Certificate of Veterinary Inspection (CVI) completed no more than 7 days prior to importation into Oregon; and
    • A valid Import Permit issued by ODA. 
  • Lactating dairy cattle require: 
    • A Certificate of Veterinary Inspection (CVI) completed no more than 7 days prior to importation into Oregon; and 
    • A valid Import Permit issued by ODA; and 
    • A negative individual or laboratory-pooled PCR test for influenza A, conducted on milk samples collected no more than 7 days prior to importation into Oregon. ​​

The full rule is available online through the Oregon Secretary of State's website. View Oregon Administrative Rule 603-011-5007.

Signs in Dairy Cattle

On affected farms, on average, 10-20% of cattle are reported as being clinically affected, with no associated mortality. Affected cattle generally recover in 2-3 weeks. The primary symptoms reported in clinically affected dairy cattle include: 

  • Rapid onset illness, specifically among older, lactating cows
  • Decreased herd-level milk production
  • Acute, sudden drop in production
  • Decrease in feed consumption
  • Abnormally dry feces
  • Fever
  • Thicker, more concentrated, colostrum-like milk​​

Reporting​​

Suspected cases of HPAI, including in cattle that fit the described signs above, must be immediately reported to the Oregon State Veterinarian (503-986-4711). HPAI in any species is considered a foreign animal disease and immediate reporting of suspected cases is required.

Food Safety

Ground Beef

According to the USDA, if the H5N1 virus were to end up in consumer beef, cooking the meat to an internal temperature of 165 degrees Fahrenheit will kill it just like it kills E. coli and other viruses.

Milk Products

On May 1, 2024, FDA announced results from a national commercial milk sampling study underway in coordination with USDA. The study includes 297 total retail dairy samples. New preliminary results of egg inoculation tests on a second set of 201 quantitative polymerase chain reaction (qPCR)-positive retail dairy samples, including cottage cheese and sour cream, in addition to fluid milk, show that pasteurization is effective in inactivating HPAI. This testing did not detect any live, infectious virus.

Precautions for Raw Milk, Raw Milk Products & Discarded Raw Milk

The FDA has a long-standing recommendation to consumers not to consume raw milk (milk that has not been pasteurized). Because of the limited information available about the possible transmission of H5N1 virus via raw milk, the FDA continues to recommend that industry does not manufacture or sell raw milk or raw milk products, including raw milk cheese, 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.

Importantly, the FDA has also recommended producers take precautions when discarding milk from affected cows so that the discarded milk does not become a source of further spread. Producers should consult with their state regulatory authorities for specific recommendations or requirements; however, such precautions should include heat treatment, pasteurization or its equivalent, of discarded milk prior to dumping in lagoons or application of waste solids and ensuring biosecurity around lagoons (e.g., ensuring that animals and birds do not have access to lagoons). Any raw milk or raw milk products from exposed cattle that are fed to calves (or to other animals, such as farm cats) should be heat treated or pasteurized.

Cats

Several farm cats in Texas died after drinking raw milk from dairy cows infected with H5N1. Cats are susceptible to avian influenza viruses. While this does not pose a risk to the majority of domestic cats at this time, cats with exposure to wild birds and potentially infected milk, such as on a dairy farm, should be treated with caution. Wear protective clothing (gloves, mask, etc.) if handling cats that show respiratory and/or neurological symptoms. Vaccinate cats against rabies and respiratory diseases.

Sources: ODA, FDA, Ars Technica, Farm Forum

Updated: May 2, 2024