#19,037
While HPAI H5N1 has yet to escalate into a human pandemic, it is most assuredly an epizootic in the animal world - and by some estimations - a Panzootic (see ISIRV: Update on H5N1 Panzootic: Infected Mammal Species Increase by Almost 50% in Just Over a Year).
Blind spots include all of Russia, Central Asia, much of Africa, Northern Canada, and the interior of South America (note: Australia/NZ are testing, but the virus has not shown up yet).The FAO map (above) of outbreaks reported since Oct 1st 2025 doesn't even come close to depicting the true extent of HPAI's impact. Many countries simply do not test extensively - or are unwilling to report outbreaks - often for political or economic reasons.
Tens of thousands of mammalian deaths (aquatic, foxes, rodents, cats, etc.) have been reported (see Nature Reviews: The Threat of Avian Influenza H5N1 Looms Over Global Biodiversity), but they likely only scratch the surface.
In the United States, nearly 1,100 herds of dairy cattle have been confirmed infected with HPAI H5N1, although many studies suggest this is likely an undercount (see Nature: A Mathematical Model of H5N1 Influenza Transmission in US Dairy Cattle).
While the worst case scenario is arguably another severe pandemic, a runner-up would be a high impact panzootic, affecting cattle, pigs, poultry, or other high-value livestock.
In the past we've looked at the devastating effects of ASF (African Swine Fever) in China (see ASF In China: Epizootic or An EpicZootic?), Foot and Mouth Disease (FMD) in South Korea), BSE in Great Britain, and even the great Equine Epizootic of 1872.
The USDA lists 8 Animal Diseases of Concern (and 51 diseases of crops), with both HPAI and some LPAI viruses on their list. This list is a `living document' and could be revised if new threats emerge.
All of which brings us to a review article published in Nature Comms which looks at the economic impact of three different scenarios of an HPAI H5 cattle epizootic in the United States; ranging from:
- S1 (the current situation)
- S2 (a realistic expansion)
- S3 (reasonable worst case)
While not as costly as a human pandemic, any increase in cattle transmission and/or morbidity & mortality would likely also increase the chances of a spillover to humans.
The bottom line, however, seems pretty obvious.
If we continue to dither, and allow HPAI H5N1 to spread in cattle, we risk a range of potential bad outcomes. Some worse than others, but all worth avoiding if possible.
Due to its length, I've only posted the link, the abstract, and brief excerpt. Click the link to read it in its entirety.
Guillaume Morel, Anh Pham, Christian Morgenstern, Joseph T. Hicks, Thomas Rawson, Victoria Y. Fan, W. John Edmunds, Giovanni Forchini & Katharina Hauck
Communications Earth & Environment , Article number: (2026) Cite this article
We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.
Abstract
The outbreak of Highly Pathogenic Avian Influenza H5N1 in U.S. dairy cattle poses substantial risks to public health, economic sustainability of farming, and global food systems. Using a Computable General Equilibrium model, we simulate its short- to medium-term impacts on Gross Domestic Product and other macro-economic outcomes for the US and its main trading partners.We simulate impacts under the current situation and realistic and reasonable worst-case scenarios. We estimate domestic economic losses ranging between 0.06% and 0.9% of US GDP, with losses to the dairy sector ranging between 3.4% and 20.6%. Trading partners increase dairy production to compensate for the loss.
Current government subsidies are about 1.2% (95% HDI: 1% to 1.4%) of output losses, and likely insufficient to incentivise farmers to step up surveillance and biosecurity for mitigating the possible emergence of H5N1 strains with pandemic potential into human populations.
(SNIP)
Despite the limitations, this study provides insight into the potential economic impacts of an H5N1 outbreak for the US and its trading partners. These economic impacts would pale in comparison to the health and economic impacts of an H5N1 outbreak among humans.Recent research suggests that the virus has gained genetic mutations in the months since it was first detected in cattle, increasing the risk of zoonotic spillover 5 ,34 . Compared with ten months ago, the virus now has more opportunities to adapt to its new mammalian hosts because of insufficiently controlled transmission, resulting in increasing numbers of infections amongst cows and other animals across the United States 4 .
Considering the high potential economic losses, and the potential risk to human health, the currently introduced measures are disproportionately lax given the scale of the potential impact. We estimate that the current subsidies for enhanced testing and biosecurity (around $98m) are covering about 1.2% of the aggregate output loss of the dairy, cattle, and raw milk sector due to the outbreak. There is robust research evidence on the economic benefits of animal tracing systems.The European Commission mandates that for the purpose of outbreak control, all bovine animal movements, births and deaths must be electronically registered within 7 days to the authorities. There is no such nationwide tracing system in the USA, although some states have introduced them. Animal tracking, combined with enhanced monitoring and biosecurity, should help reduce the risk of the current outbreak from escalating, reduce economic costs to farmers, and mitigate the potential emergence of highly virulent H5N1 strains with pandemic potential into human populations.
