Influenza A in U.S. Dairy Cattle 2024

HPAI in U.S. Dairy Cattle 2024

Overview: The U.S. Department of Agriculture (USDA), Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), as well as state veterinary and public health officials, are continuing to investigate an illness among dairy cows that is causing decreased lactation, low appetite, and other symptoms. To date no similar illness, nor H5N1 detections, have been reported in Canadian dairy cattle.
Over the past weeks, H5N1 has also been detected in the U.S. in one dairy worker on an affected farm, cats on affected farms, and goats in one farm in MN (without reported links to affected dairy herds). Our understanding of H5N1 in North American mammals continues to grow. LINK

Recent reports of dairy HPAI detections in the U.S.

2 April, 2024 Influenza A detection in Idaho Dairy Cattle  LINK


1 April, 2024 Influenza A detection in New Mexico Dairy Cattle LINK


March 29, 2024 HPAI detection in Michigan dairy cattle LINK

                           HPAI detection in Idaho dairy cattle LINK 

March 25, 2024  HPAI detection in Texas and Kansas dairy cattle LINK

Clinical signs in U.S. dairy herds reporting HPAI detections

The clinical case presentation that has been reported is:

1. Sudden reduction in feed intake with decreased ruminations evident on physical exam and rumination monitors.

2. Sudden decrease in milk production on a herd level. Individual cows that are more severely affected have milk that is yellow and concentrated with the appearance of colostrum.

3. Variations in manure consistency with the most common finding being tacky to dry manure, although some cows appear to have diarrhea.

4. Secondary infections such as pneumonia and mastitis.

The affected cases appear to be in lactation 2 or greater animals that are more than 150 days in milk. Calves, heifers, and dry cows appear not to be affected. Morbidity is around 10% of the animals. Cases present over a 7-10 day time period and the first herds report a return to near normal production in 3 weeks.


These symptoms have been reported by the American Association of Bovine Practitioners and the USDA-APHIS.

Biosecurity resources

Dairy Biosecurity Recommendations – HPAI and More_AABP LINK


proAction: Canadian Dairy Quality Assurance Program Biosecurity Module LINK


USDA-APHIS Secure Milk Supply (SMS) Dairy Biosecurity Resources LINK

Frequently Asked Questions

Canadian Food Inspection Agency: Highly pathogenic avian influenza (HPAI) in livestock LINK


USDA-APHIS: Detection of Highly Pathogenic Avian Influenza in Dairy Herds: Frequently Asked Questions LINK


USDA-APHIS: Questions and Answers Regarding Milk Safety During Highly Pathogenic Avian Influenza (HPAI) Outbreaks   LINK