Chickens, Cows, and Cats: A Barnyard Story about Bird Flu - Cynda Crawford, DVM, PhD

Описание: Dr. Cynda Crawford discusses H5N1 or "Bird Flu" and its impact on domestic cats, poultry and dairy cattle at the 2025 Health Watch USA(sm) webinar: "Combating Infectious Disease Challenges." Health Watch USA(sm) webinar. Aug. 29, 2025.

Presentation Abstract:

The presentation by Dr. Cynda Crawford explores the evolving ecology and impact of highly pathogenic H5N1 avian influenza (bird flu) across the United States. Traditionally, wild waterfowl are the natural hosts of influenza A viruses, but in recent years, the H5N1 subtype has spread extensively, affecting all 50 U.S. states’ poultry, leading to the infection and depopulation of approximately 175 million birds.

Since 2022, H5N1 has spilled over from wild birds into commercial and backyard poultry, then into a wide range of mammals—over 200 terrestrial and marine species, including seals, sea lions, and for the first time, dairy cattle. Dairy cows experience H5N1 as a localized mammary gland infection resulting in mastitis and sudden drops in milk production, with high viral loads detected in milk but generally nonfatal outcomes for the animals. New genotypes have been identified, highlighting frequent viral reassortment.

A notable event occurred in March 2024 when barn cats on a Texas dairy farm died rapidly after consuming raw milk from infected cows, marking the first documented mammal-to-mammal transmission of H5N1 via milk. Cats suffer severe, often fatal neurological disease, and the mortality rate among infected cats is estimated at 50–70%. There is no current evidence of cat-to-cat or cat-to-human transmission. The situation raises public health concerns about cows and cats as potential “mixing vessels” for new, more dangerous H5N1 strains, emphasizing the need for enhanced surveillance, biosecurity, and consideration of vaccines for at-risk animals. (Summary AI Assisted)