Highly Pathogenic Avian Influenza (HPAI) H5N1 Virus in Livestock

Information about HPAI in dairy cattle is an evolving, fluid situation with ongoing research and policy development. Please check back frequently as the information below will be updated as it becomes available. Last updated: 5/14/2024

Bovine Health Alert

There are no Bovine Health Alerts at this time.

Current HPAI H5N1 in Livestock Guidance For California Producers

  1. CDFA Dairy Cattle Import Order: Bovine Associated Influenza A (H5N1) Syndrome Entry Requirements for Importing Dairy Breed Cattle from Affected states (4/4/2024)
  2. What to Expect if You Suspect HPAI in Your Herd (5/16/2024)

Clinical Signs

Infected cattle may be asymptomatic (subclinical) or symptomatic (clinical) and virus is predominantly found in milk and mammary tissue regardless of symptoms.

Clinical signs may include:

  1. Decrease in feed consumption with a simultaneous decrease in rumination and rumen motility
  2. Respiratory signs including clear nasal discharge
  3. Acute drop in milk production. Severely affected cattle may have thicker, concentrated, colostrum-like milk or produce no milk at all.
  4. Abnormal tacky or loose feces
  5. Lethargy
  6. Dehydration
  7. Fever

Sampling Protocol for HPAI in Livestock

  1. Protocol for cows with clinical signs of HPAI
    1. For dairies with suspect clinical signs contact your district office for regulatory personnel to conduct a Foreign Animal Disease investigation (FADi).
  2. Protocol for lactating dairy cattle moving interstate (not direct to slaughter movements)
    1. All lactating dairy cattle moving interstate require a Certificate of Veterinary Inspection (CVI) and matrix-A negative HPAI test from a National Animal Health Laboratory Network (NALHN) laboratory within seven (7) days of movement.
    2. Samples must be collected by an accredited veterinarian, a sample collector approved by a state animal health official, or a designated individual at a farm that was trained to collect milk and nasal swab samples.
    3. The sample must be sent to an approved NAHLN laboratory (UC Davis California Animal Health and Food Safety (CAHFS) Laboratory is currently only approved laboratory in California)
    4. For groups/lots of 30 or fewer animals moving interstate, all animals being moved must be tested. If more than 30 animals are moving interstate, only 30 animals total must be tested.
  3. Protocol for non-lactating dairy cattle moving interstate and any dairy cattle moving interstate direct to slaughter:
    1. Currently no testing required, must have CVI within seven (7) days of movement.

California Movement Restrictions and Interstate Movement Requirements for Dairy Cattle

All California CVIs must include the following statement: "All animals identified on this Certificate of Veterinary Inspection (CVI) have been inspected and do not originate from a premises with a confirmed detection of Bovine Associated Influenza A (H5N1) Syndrome** or that is currently under investigation as a suspect premises."

  1. All lactating dairy cattle moving interstate require a CVI and matrix-A negative HPAI test from a NALHN laboratory within seven (7) days of movement.
  2. Dairy cattle moving interstate direct to slaughter are exempt from the test requirement but do require a CVI or a state-approved owner shipper statement.
  3. Lactating dairy cattle from herds which have tested positive for Influenza A are not eligible for interstate movement for thirty (30) days from the most recent collection of any sample that tests positive from any individual animal in the herd. Re-testing may occur after this 30-day period.
  4. Lactating dairy cattle with clinical signs consistent with HPAI in dairy cattle are ineligible for interstate movement (including to slaughter) as per 9 C.F.R. 71.3(b).

Recommended Biosecurity Measures for Livestock Operations

CDFA strongly encourages dairy farms and processors to:

  1. Review biosecurity protocols, including industry biosecurity resources such as those that may be found on the CDFA website for the Secure Food Supply Program, as well as the resources that can be found on the FARM/NMPF Everyday Biosecurity manual (Biosecurity - National Dairy FARM Program) and the Secure Milk Supply website (Secure Milk Supply Plan).
  2. Continue to be vigilant to observe for clinical signs consistent with this outbreak such as acute loss of animal appetite and rumination; significant/acute drop in milk; changes in manure consistency.
  3. Contact your herd veterinarian if you observe animal conditions outside of the ordinary. This has not currently been reported in California, but it is a reminder to enforce biosecurity on your dairy operation or when visiting other dairy operations.

Disease Spread

The primary introduction of disease into dairy herds has been predominantly via exposure to wild birds. The exact mechanism of spread is currently unknown, although there is potential for viral spread through milk. USDA has identified spread between cows within the same herd, spread from cows to poultry, spread between dairies associated with cattle movements, and cows without clinical signs that have tested positive. On April 16, APHIS microbiologists identified a shift in an H5N1 sample from a cow in Kansas that could indicate that the virus has an adaptation to mammals.

Diagnosis & Prevention

There is no specific treatment or cure for animals infected with HPAI H5N1 and there are currently no vaccines available to prevent this disease. Veterinarians and livestock owners who suspect an animal may have Highly Pathogenic Avian Influenza (HPAI) H5N1 should immediately contact a State or Federal animal health authority.

Testing for HPAI H5N1 in milk samples (lactating cattle) or nasal swab samples (non-lactating cattle) can confirm HPAI H5N1 viral infections.

Even with the best defense measures, HPAI H5N1 can still affect your herd. The following are ways to help protect livestock:

  • No movement of clinical dairy cattle for 30 days past last matrix-A positive HPAI test
  • Ensure cattle trailers are only used to haul your cattle or thoroughly clean and disinfect trailers between use.
  • Adhere to an isolation period of a minimum of 30 days for new arrivals with active observational surveillance for clinical signs.
  • Feed only heat treated/pasteurized milk to calves and other livestock and heat treat/pasteurize any milk being discarded.
  • Milk affected animals last with thorough cleaning and disinfection of milking equipment (utilizing dedicated milking units if possible)
  • Separate animals with clinical signs from healthy animals
  • Use dedicated coveralls and boots when handling clinical animals (use dedicated farm personnel to only handle clinical animals where possible).
  • Use good personal hygiene measures including freshly laundered clothes and showering before visiting dairy farms or processing facilities.
  • Limit vehicle/visitor traffic to strictly essential deliveries/visits (feed, milk, waste removal).
  • Clean and disinfect vehicles crossing the line of separation and entering/leaving the farm or obtain a commercial car wash before and after visiting a livestock operation.
  • Engage state and federal wildlife agencies for wild bird mitigation.

CDFA appreciates your efforts to protect livestock health in California on a daily basis. Remember, people, equipment, and vehicles can easily spread dangerous diseases from one location to another.

More information on HPAI H5N1 in Livestock

  1. USDA: Highly Pathogenic Avian Influenza (HPAI) Detections in Livestock
  2. USDA Federal HPAI Livestock Testing Order: Federal Order Requiring Testing for and Reporting of Highly Pathogenic Avian Influenza (HPAI) in Livestock
  3. APHIS Requirements and Recommendations for Highly Pathogenic Avian Influenza (HPAI) H5N1 Virus in Livestock

Milk Safety

Questions and Answers Regarding Milk Safety During Highly Pathogenic Avian Influenza (HPAI) Outbreaks | FDA

Public Health and Dairy Worker Safety

APHIS Recommendations for Highly Pathogenic Avian Influenza (HPAI) H5N1 Virus in Livestock for Workers (4/12/2024)