Abstract
We present a stochastic metapopulation transmission model that simulates the spread of H5N1 avian influenza through individual dairy cows in 35,974 dairy herds in the continental United States. Transmission is enabled through the movement of cattle between herds, as indicated from Interstate Certificates of Veterinary Inspection (ICVI) 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 likely impact of intervention methods to date 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, due to the network of cattle movements and distribution of the respective dairy populations. We quantify the extent of uncertainty in the scale of the epidemic, highlighting the most pressing data streams to capture, and which states are most expected to see outbreaks emerge next, with Arizona and Wisconsin at greatest risk. Our model suggests that dairy herd outbreaks will continue to be a significant public health challenge in 2025, and that more urgent, farm-focused, biosecurity interventions and targeted surveillance schemes are sorely needed.
Source: MedRxIV, https://www.medrxiv.org/content/10.1101/2025.01.28.25321250v1
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