Nat Commun . A mathematical model of H5N1 influenza transmission in US dairy cattle

[tetano]

Nat Commun


. 2025 May 8;16(1):4308.
doi: 10.1038/s41467-025-59554-z. A mathematical model of H5N1 influenza transmission in US dairy cattle

Thomas Rawson ¹ , Christian Morgenstern ² , Edward S Knock ² , Joseph Hicks ² , Anh Pham ² , Guillaume Morel ^{2 3} , Aurelio Cabezas Murillo ⁴ , Michael W Sanderson ⁵ , Giovanni Forchini ^{2 3} , Richard FitzJohn ² , Katharina Hauck ² , Neil Ferguson ²



Affiliations

• PMID: 40341525
• DOI: 10.1038/s41467-025-59554-z

Abstract

2024 saw a novel outbreak of H5N1 avian influenza in US dairy cattle. Limited surveillance data has made determining the true scale of the epidemic difficult. We present a stochastic metapopulation transmission model that simulates H5N1 influenza transmission through individual dairy cows in 35,974 herds in the continental US. Transmission is enabled through the movement of cattle between herds, as indicated from Interstate Certificates of Veterinary Inspection data. We estimate the rates of under-reporting by state and present the anticipated rates of positivity for cattle tested at the point of exportation over time. We investigate the impact of intervention methods on the underlying epidemiological dynamics, demonstrating that current interventions have had insufficient impact, preventing only a mean 175.2 reported outbreaks. Our model predicts that the majority of the disease burden is, as of January 2025, concentrated within West Coast states. We quantify the uncertainty in the scale of the epidemic, highlighting the most pressing data streams to capture, and which states are expected to see outbreaks emerge next, with Arizona and Wisconsin at greatest risk. Our model suggests that dairy outbreaks will continue to occur in 2025, and that more urgent, farm-focused, biosecurity interventions and targeted surveillance schemes are needed.

[Commonground]

MAY 15, 2025
NEW MODEL REVEALS H5N1 IS SPREADING UNDETECTED IN US DAIRY HERDS
Excerpt:

A powerful simulation of H5N1 transmission across 35,974 US herds shows that the virus is far more widespread than reported, raising urgent calls for better farm surveillance and stronger disease control.

In a recent study in the journal Nature Communications, researchers developed and tested a novel stochastic metapopulation transmission model to predict the scale, the most important epidemiological data, and the states at highest risk in the ongoing H5N1 avian influenza epidemic in US dairy cattle.

-snip-

Study findings
Susceptible-Exposed-Infected-Recovered (SEIR) infection dynamics models (20,000 stochastic simulations) revealed that most current H5N1 infections in dairy cattle are concentrated along the country’s West Coast. While the model was observed to overestimate case densities in some predicted outbreaks (Texas, Ohio, and New Mexico), the model successfully simulated outbreaks for states with frequent reporting like California, though it overestimated reported outbreaks in some other states (Texas, Ohio, and New Mexico), which the researchers interpret as potential under-reporting in those states relative to California’s baseline.

Alarmingly, only 16 of the 26 states where the model indicated a majority of simulations would see an H5N1 outbreak by December 2nd, 2024, had actually reported one, suggesting a high degree of under-reporting. Arizona and Wisconsin are expected to become future hotspots of H5N1 outbreaks. Indiana and Florida are also at significant risk of H5N1 outbreaks.

Investigations of current mitigation measures reveal that they are insufficient to control, much less reverse, the prevalence of H5N1 in the country. Notably, the only current mitigation measure enforced across states is testing exported cattle (screening up to 30 cows/herd for H5N1). Model predictions revealed that increasing this screening to even 100 cows/herd would result in only a slight reduction in mean outbreaks and would not fundamentally alter the epidemic’s trajectory.

Notably, the SEIR infection model does not account for other zoonotic viral reservoirs in model predictions. The ongoing avian influenza epidemic and the possibility of these birds infecting cattle may exacerbate model predictions.

Conclusions
The present study and the SEIR model it presents suggest that current reports on the prevalence of H5N1 dairy cattle infections are an underrepresentation of the true concentration of the disease within the United States. Current anti-H5N1 transmission interventions are insufficient to prevent additional outbreaks throughout 2025. At the highest risk of future outbreaks, Arizona, Wisconsin, Florida, and Indiana require additional surveillance efforts.

“Significant increases in testing are urgently required to reduce the uncertainty of model projections and provide decision-makers with a more accurate picture of the true scale of the national epidemic.”

https://en.edairynews.com/new-model-reveals-h5n1-is-spreading-undetected-in-us-dairy-herds/