On March 25, the U.S. Department of Agriculture (USDA), Centers for Disease Control (CDC), and the Food and Drug Administration (FDA) announced that they detected highly pathogenic avian influenza (HPAI) in dairy cattle in Kansas, Texas and Michigan and have presumptive diagnoses in New Mexico and Idaho.
Clinical signs and recovery
The cows that have tested positive in their unpasteurized milk samples had clinical signs of low appetite, sudden drop in milk production, colostrum-like milk, poor rumen motility, changes in feces, dehydration, lethargy, and a fever. Older cows that are in mid-lactation may be more likely to become sick than younger cows or fresh cows or heifers.
The dairy cattle that have tested positive to HPAI have recovered with no death loss as of March 27. This is unlike the very high death rates of HPAI in birds and poultry. Therefore, unlike with poultry, the USDA does not anticipate that the dairy herds will need to depopulate.
Transmission
It is possible that HPAI is being transmitted between cows, not just wild birds to cows. The birds that passed HPAI to the cows in Texas are thought to be pigeons, grackles and blackbirds.
Mammals are susceptible to HPAI. There was a report of it being found in neonatal goats in Minnesota that shared pasture and a water source with poultry.
Zoonosis
People that are in direct contact with cows that are positive for HPAI are at risk for contracting HPAI, although the risk is small. The strain confirmed in the Texas and Kansas dairy cattle does not have any mutations that would make it more transmissible to humans.
Biosecurity
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The USDA is recommending that good biosecurity practices be adhered to. They are also recommending to test dairy cattle from these regions before moving them, isolate sick cattle, and in general, minimize dairy cattle movement.
Safety of commercial milk
The commercial milk supply is pasteurized before entering the market, making it safe for consumption. Pasteurization is the heating process in which milk is partially sterilized, making bacteria and viruses inactive. Dairy cattle that are sick can still be milked but this milk must be discarded. Only milk from healthy dairy cows can go on to be pasteurized for human consumption. It is also recommended that if the milk is being fed to calves, it be pasteurized as well.
Raw milk
Raw milk drinkers must beware. HPAI can be found in nonpasteurized milk from sick cows and has the potential to cause sickness in people. Raw milk can also harbor salmonella, listeria, campylobacter, E. coli, and several other types of bacteria and viruses.
Milk loss
As of late March, there are not enough affected cattle to have an effect on the milk supply. Also, during the spring, the United States typically has a surplus of milk due to the increase in production.
Meat supply
The USDA ensures us that the meat supply is safe. Always remember to cook your meat to a safe internal temperature that would kill a virus like HPAI.
What producers can do
If you notice the above clinical signs in your dairy cattle and have ruled out any common causes of these signs, make sure to reach out to your local veterinarian.
Lainie Kringen-Scholtz, DVM, is owner of True North Veterinary Health and associate at Big Sioux Veterinary Care. Reach her at truenorthveterinaryhealth@gmail.com or PO Box 117, Wentworth, SD 57075.