Science News

Article originally written by Felipe Quintero Ochoa ’27.

Bird flu has been a trending topic in the field of etiology because of its spread to non-avian organisms, including humans and cows. As of June 8, 2024, H5N1 (H5 bird flu) has been detected by farms in 9 states – Michigan, Texas, Idaho, New Mexico, Colorado, South Dakota, Kansas, North Carolina, and Ohio (6 C.E.). Symptoms of the H5N1 virus include decreased feed consumption, diarrhea, abnormal lactation, thickened or clotted milk, labored breathing, fever,  and dehydration (6 C.E.).

While the symptoms may seem daunting, only 10% of cows are affected by H5N1 on average, and less than 2% of cows are culled or killed because of H5N1 (6 C.E.). Farms reported that pre-weaned calves, beef animals, weaned unbred dairy heifers, and dairy bulls exhibited no clinical signs (6 C.E.). In contrast, first-time milking dairy second-time milking dairy cows, 3rd or high-milking dairy cows, dry dairy cows, and bred dairy heifers exhibited clinical signs (6 C.E.).

As for the transmission of H5N1, farms have reported that contaminated equipment and shared personnel between farms can cause transmission. Also, nutritionists, veterinarians, hoof trimmers, contract haulers, and other visitors in frequent contact with cattle are at risk for disease transmission (6 C.E.). In addition, while scientists have researched the transmission risk caused by manure equipment, the risk of H5N1 transmission is low based on manure samples (6 C.E.). 

Overall, while H5N1 is a relevant and dangerous variant of bird flu, its effects have not come to fruition and have minimally impacted the cow population. However, scientists must analyze variants in H5N1 that could increase morbidity or mortality rates in order to develop a vaccine and prevent a cow health crisis.

Sources:

(6 C.E.). Highly Pathogenic Avian Influenza H5N1 Genotype B3.13 in Dairy Cattle: National Epidemiological Brief (pp. 1–5) [Review of Highly Pathogenic Avian Influenza H5N1 Genotype B3.13 in Dairy Cattle: National Epidemiological Brief]. USDA – Animal and Plant Health Inspection Service.

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