Since then, more than 1,000 herds across 17 states have seen confirmed cases, including an Ohio herd of 3,876 cows that was infected in 2024, after 40-some seemingly healthy cows were transferred into their midst; this is the herd that appears in the Cornell study. Using cow- and herd-level data from before, during, and after the HPAI outbreak — with diagnosis established by severe mastitis and accompanying production and behavioral indicators — researchers tracked production loss as well as other metrics to estimate the overall economic toll of the outbreak. The 777 animals who were deemed HPAI-infected were acutely ill for an average of 7.9 days, but the aftereffects lingered. The 60-day period of illness and postclinical recovery showed an average production drop-off of nearly 2,000 pounds per cow, which, when added to mortality, replacement, and early removal from the herd, brings the total cost to about $950 per clinically affected cow.
In addition to tracking how hard the virus hit the herd, the researchers also noted where it landed: only one of the 777 infected cows was dry; most of the others were multiparous and in mid- to late-stage lactation. For assessment beyond production, death — natural or through euthanization — was documented. Of the sick cows, 53 died or were euthanized within two weeks of diagnosis. Add to this the 245 later-culled cows (those culled 20 days after diagnosis), and it amounts to a sextupled increase in risk for death compared to the uninfected members of the herd.
Extrapolated to a larger scale, these numbers — both production loss and high-level herd costs — call for measures to mitigate any outbreak’s potential ripple effects. The study authors recommended a two-pronged approach to HPAI: first, farms should bump up biosecurity measures, and second, research should focus on vaccine development.
Check out our past coverage on HPAI:
Learnings and considerations for HPAI
The path to putting HPAI in the rearview mirror
