H5N1 is spreading undetected in U.S. dairy herds-new research reveals why current controls are failing and what must change to protect your farm.
EXECUTIVE SUMMARY: A new modeling study published in Nature Communications shows the H5N1 avian influenza epidemic in U.S. dairy cattle is far more widespread than official reports indicate, with significant under-reporting across many states. The research, using a nationwide SEIR model, identifies Arizona, Wisconsin, Indiana, and Florida as future outbreak hotspots and warns that current mitigation measures-mainly limited pre-movement testing-are insufficient to control the epidemic, which is expected to continue through 2025. The study highlights the urgent need for increased testing and robust, farm-level biosecurity, especially since wild bird spillovers are not fully accounted for in current models. The findings have major implications for disease control, economic stability, and public health, underscoring the necessity of a coordinated One Health approach. Dairy professionals are urged to critically evaluate their current practices and prepare for a more challenging and persistent threat than previously recognized.
KEY TAKEAWAYS:
- H5N1 is likely far more prevalent in U.S. dairy herds than official numbers show, with major under-reporting in at least 10 states.
- Current control measures, especially limited pre-movement testing, are insufficient to halt or reverse the epidemic.
- Future outbreak hotspots include Arizona, Wisconsin, Indiana, and Florida, demanding urgent, enhanced surveillance and biosecurity.
- Wild bird spillovers continue to introduce new viral strains, complicating control and requiring a dual focus on cattle and wildlife management.
- A coordinated, One Health approach and significantly increased testing are essential to protect both the dairy industry and public health.
The dairy industry is facing a crisis far greater than official numbers suggest. A groundbreaking mathematical model published in Nature Communications reveals H5N1 avian influenza is silently spreading through U.S. dairy operations, with surveillance missing infections in at least 10 states. Current testing protocols are fundamentally inadequate, biosecurity measures are failing, and the consequences for animal health and your bottom line could be devastating without immediate action.
The Unseen Epidemic: What USDA Isn’t Telling You
When USDA officials quote figures of about 1,053 affected herds across 17 states, they share what they know – but not what’s happening. The revolutionary modeling study by Rawson et al. demonstrates what many progressive dairy producers have suspected all along: H5N1 has established a foothold far beyond what official testing has uncovered.
Here’s the hard truth – the traditional approach of waiting for clinical signs and testing only during outbreaks is as outdated as tie-stall barns in a robotic milking world.
The Rawson team’s sophisticated “stochastic metapopulation SEIR model” (think of it as a virtual dairy industry that simulates disease spread) makes one thing painfully clear. For 26 U.S. states, the model predicted outbreaks by December 2024, yet only 16 of these states had reported one. That 10-state gap represents potentially hundreds of infected herds operating without awareness of their H5N1 status, spreading the virus while missing the opportunity for early intervention.
Why is this happening? The answer lies in a perfect storm of:
- Surveillance systems designed for visual detection miss subclinical cases
- Financial disincentives that make producers hesitant to test voluntarily (would you risk a quarantine that could cost your 1,000-cow dairy $2.1 million over six months?)
- State-by-state variations in testing resources and priorities
- Testing protocols that fundamentally misunderstand the viral dynamics of H5N1
The comfortable fiction that H5N1 is a manageable, contained problem is costing us the opportunity to get ahead of this disease. And let’s be honest – the dairy industry has seen this movie before with Johne’s disease, tuberculosis, and even mastitis pathogens, where the absence of evidence was mistakenly interpreted as evidence of absence.
The Geography of Risk: Is Your Farm Next?
The model doesn’t just tell us where H5N1 is hiding – it predicts where it’s heading next. According to the simulations, most current H5N1 infections are concentrated along the West Coast, but four states face imminent risk:
- Arizona is identified as ground zero for the next wave
- Wisconsin – America’s Dairyland is poised for a significant outbreak
- Indiana – facing substantial transmission potential
- Florida is at risk of an outbreak emergence
If you’re operating in these states, consider this your wake-up call. The virus isn’t “coming” – it’s likely already circulating in neighboring operations that supply your replacements or purchase your animals.
The model incorporates detailed cattle movement data from the U.S. Animal Movement Model (USAMM) and Interstate Certificates of Veterinary Inspection to track how the virus hitchhikes across regions. Think of this as mapping the same routes your cattle dealer follows when sourcing those springing heifers from five states away.
But here’s what should keep you up at night – the model doesn’t even account for wild bird introductions. The recent detection of a distinct H5N1 genotype (D1.1) in Arizona dairy cattle confirms that new spillover events from wild birds continue to occur independently of cattle-to-cattle transmission. That means even if we perfectly controlled cow-to-cow spread, we’d still face new infections from birds.
It’s like focusing your mastitis control solely on cow-to-cow transmission while ignoring environmental pathogens. You might block one route, but you’re still getting infections.
Current Mitigation: Rearranging Deck Chairs on the Titanic?
Let’s call it what it is – our current approach to controlling H5N1 is failing. The federal government’s primary strategy, pre-movement testing, involves screening up to 30 cows per herd before interstate movement.
How practical is this approach? According to the model, these interventions have prevented only 175.2 outbreaks out of thousands of potential infections. Even more damning, the researchers simulated what would happen if we tripled testing intensity to 100 cows per herd. The result? Only a slight reduction in outbreaks – nowhere near enough to turn the tide.
Consider this table that lays bare the fundamental flaws in our current approach:
| Limitation | Explanation | Real-World Comparison |
| Sample Size Problem | Testing 30 cows in herds of 1,000+ misses’ infections | Like trying to find SCC problems by testing three cows in your 100-cow herd |
| Timing Challenge | Viral shedding peaks rapidly (1-2 days) with a short duration (~6 days) | Like trying to catch a heifer in heat with once-daily observation |
| Asymptomatic Carriers | Many infected cows show minimal symptoms | As deceptive as subclinical hypocalcemia – invisible but costly |
| Wild Bird Reservoir | Testing cattle ignores ongoing spillovers from birds | Like treating clinical mastitis while ignoring bedding management |
| Implementation Variability | States have wildly different compliance levels | As inconsistent as the SCC standards are across milk cooperatives |
Will we stand by while regulators continue pushing interventions that their modeling shows are inadequate? The dairy industry deserves better than symbolic measures that create paperwork without results.
Economic Reality: The True Cost Beyond Bulk Tank Losses
H5N1 isn’t just an animal health crisis – it’s a financial wrecking ball hitting dairy farms where it hurts most.
By The Numbers: What H5N1 Costs Real Farms
Large Operations (1,000+ cows)
- Potential revenue loss during 6-month quarantine: $2.1 million
- Average loss per infected cow: $950
- Projected annual insurance premium increase: 22%
Mid-Sized Operations (200-999 cows)
- Proportional losses of $420,000-$2.1 million during quarantine
- Additional labor costs from 14% wage inflation for dairy workers
- Biosecurity implementation costs: Often $30,000+ for equipment and facility modifications
Small Operations (Under 200 cows)
- Proportionally higher per-cow impact due to fixed costs spread across fewer animals
- Greater vulnerability to cash flow disruption
- Limited capital for implementing comprehensive biosecurity measures
Infected cows typically experience around 20% decreases in milk production, equivalent to a moderate case of clinical mastitis, but spread across your entire string. A study of an infected Ohio herd estimated losses at approximately $950 per affected cow. This translated to a total loss of $737,500 for that operation during just the observation period.
California’s experience foretells what could happen nationwide. The state has seen milk output drop by 5.7% to 9.2% year-over-year in affected regions. Some analysts project that U.S. milk production could fall by as much as 15% in certain quarters if the outbreak continues unchecked, roughly equivalent to removing Wisconsin’s entire output from the national milk pool for three months.
Beyond lost milk, the cascading financial effects include:
- Implementation costs for enhanced biosecurity – not budgeted in your current fiscal year
- Labor inflation of 14% for dairy workers, when finding reliable milkers was already nearly impossible
- Insurance premium spikes of 22% year-over-year – hitting cash flow at the worst possible time
- Veterinary bills and treatment costs – draining resources that should be going toward genetic advancement and facility improvements
For consumers, dairy prices rose 7.7% year-over-year in January 2025, with projections suggesting potential milk price hikes of 8-10% through mid-2025 if outbreaks persist.
The harsh reality? These financial pressures will disproportionately crush smaller operations with limited financial reserves. If current trends continue, we’ll see the acceleration of dairy consolidation, much like how increasing environmental regulations in the 1990s and 2000s pushed many family operations to exit the industry.
CASE STUDY: Meadowlark Dairy’s H5N1 Battle
Meadowlark Dairy, a 776-cow Holstein operation in Ohio, detected its first H5N1 case in October 2024 after noting a 15% drop in bulk tank production over three days. The virus spread rapidly through the milking herd despite implementing immediate biosecurity protocols.
Key impacts:
- 32% of the herd was ultimately infected over a 45-day outbreak period
- Production losses peaked at 22% below the pre-outbreak average
- Total economic damage: $737,500 during the observation period
- Recovery to pre-outbreak production took nearly 3 months
- Post-outbreak costs included replacing 15 culled animals and implementing permanent enhanced biosecurity systems
“We thought we were prepared with our existing protocols,” the operation’s herdsman noted. “But this virus moved through the herd faster than anything we’ve seen before. The milk loss was just the beginning – the real costs came in the aftermath as we rebuilt our systems.”
Biosecurity 2.0: Getting Serious About Protection
If you still rely on boot baths and visitor logs as your primary biosecurity strategy, you might as well leave your barn doors open to H5N1. This virus demands a comprehensive approach that addresses its unique transmission routes.
1. Milk Parlor Management – Your Milking System Is Ground Zero
The evidence is clear: milking equipment is a primary H5N1 transmission route within herds. The virus binds to mammary tissue, producing high viral loads in milk.
- Implement strict segregation of sick or suspect animals with dedicated milking equipment – treat them like your worst Staph aureus cows
- Establish terminal milking order (healthy first, suspect animals last) – just as you would for clinical mastitis
- Enhance sanitization protocols between animals – standard backflush systems aren’t adequate
- Train staff to recognize subtle milk changes – strip cups become your early warning system
- Increase equipment cleaning frequency – think hospital-grade protocols, not standard CIP cycles
A question that should make every dairy producer uncomfortable: Are you still treating your milking system like it’s just moving milk, rather than potentially spreading disease?
2. Bird-Proofing Your Operation
With multiple documented spillovers from wild birds, you can’t ignore this vector:
- Modify structures to reduce bird access to feed storage – bird netting in open-sided commodity sheds is now essential, not optional
- Cover feed bunks whenever possible – TMR tarps are an investment in biosecurity, not just rain protection
- Deploy bird deterrent systems strategically, just as you protect your silage bunkers
- Clean and sanitize areas with bird droppings immediately – treat them like visible manure on teats
- Redesign feed storage to eliminate wild bird access – closed systems beat open piles every time
3. Strategic Testing Beyond Minimums
Don’t wait for symptoms or government mandates:
- Implement weekly bulk tank milk monitoring – your most sensitive early detection system
- Establish baseline health metrics to catch subtle production changes – use your DHI data proactively
- Partner with your veterinarian on customized surveillance protocols – make H5N1 part of your VCPR discussion
- Budget for testing as insurance – far cheaper than dealing with a clinical outbreak
- Consider participating in the USDA’s Dairy Herd Status Program, like Johne’s certification programs
4. Movement and Introduction Protocols
Since pre-movement testing isn’t adequate alone:
- Implement more extended quarantine periods for new arrivals (minimum 30 days) – treat them like new bulls entering an AI stud
- Test animals during quarantine, not just before – catch what might have been incubating
- Consider geographical risk when sourcing animals – know your dealer networks and source farms
- Maintain closed herds where feasible – rely on genetics and sexed semen rather than purchases
- Develop contingency plans for essential movements – have protocols ready before you need them
5. Staff and Visitor Management
People can inadvertently transport the virus between farms:
- Establish clear zones on your operation, like the transition from parlor alleyway to milking pit
- Provide dedicated clothing and footwear – sharing boots between farms is professional malpractice in 2025
- Create decontamination protocols for essential visitors – your milk hauler, AI technician, and equipment repair people need specific guidance
- Educate staff about H5N1 risks and symptoms – in multiple languages that reflect your workforce
6. Waste Management
Proper handling of potentially contaminated materials is crucial:
- Never feed raw waste milk to calves – pasteurization is non-negotiable now
- Pasteurize or heat-treat dairy wastes before disposal – treat it like you would hospital pen manure
- Manage manure application to reduce wild bird attraction – watch for birds following your spreader
- Develop protocols for the safe disposal of contaminated materials, like your antibiotic residue protocols
A Hard Question: Are We Making the Same Mistakes Again?
Here’s a reality check: our industry has historically underestimated disease threats and overestimated the effectiveness of voluntary measures. From Johne’s disease to leukosis, we’ve seen time and again that without systematic, enforced control protocols, endemic diseases become accepted as “part of doing business.”
Are we willing to let H5N1 follow the same path?
The dairy industry now faces a critical choice. Will we:
- Continue with business as usual, hoping that minimal testing and basic biosecurity will somehow contain a virus that modeling shows is already escaping our detection?
- Push for meaningful, science-based reforms that acknowledge the accurate scale of this threat and implement protocols commensurate with the risk?
Ask yourself: If the Rawson model is correct (and remember, it likely underestimates the problem by not accounting for wild bird reservoirs), how comfortable are you with your current H5N1 prevention strategy?
The uncomfortable truth is that many producers avoid testing because they don’t want to know the answer. However, “strategic ignorance” has never been a sound business strategy, particularly with a disease with significant economic and potential public health implications.
The Bottom Line: A Call to Action
The Rawson model delivers a wake-up call that demands immediate response from progressive dairy producers. H5N1 is more widespread than reported, current controls are inadequate, and outbreaks will continue throughout 2025 and beyond without bold action.
What you should do right now:
- Contact your veterinarian this week to implement a strategic testing protocol for your operation, regardless of whether your state has reported cases.
- Audit your milking procedures for disease transmission risk – the parlor is your highest risk environment.
- Evaluate your feed storage and bird exclusion measures – preventing new introductions is as important as controlling existing infections.
- Develop a financial contingency plan for potential production impacts – model scenarios with 10-20% milk loss.
- Engage with state and federal officials to demand more transparent reporting and effective control measures than the current “test 30 cows” approach.
For too long, we’ve accepted the comfortable fiction that H5N1 is someone else’s problem or a manageable risk. The Rawson model strips away that illusion and challenges us to confront reality: this virus is likely already more widespread than we’ve admitted, and our current approach isn’t working.
The future of your dairy operation may depend on how quickly you accept this reality and act accordingly. Will you be among those who lead with proactive measures, or will you be forced to react when H5N1 inevitably appears in your bulk tank?
The choice – and the consequences – are yours.
The dairy industry has tackled significant disease challenges, from brucellosis to BVD, through coordinated action, science-based protocols, and producer determination. H5N1 demands that same level of unified commitment, but with even greater urgency. The time for half-measures and wishful thinking has passed.
References
- USDA APHIS. (2025, May 9). H5N1 in U.S. Dairy Cattle – Official Outbreak Statistics.
- Rawson, T., et al. (2025). A mathematical model of H5N1 influenza transmission in U.S. dairy cattle. Nature Communications, 16, 4308.
- National Milk Producers Federation. (2025, April). Economic Impact Assessment: H5N1 in U.S. Dairy Operations.
- USDA APHIS. (2025, February). Detection of H5N1 Genotype D1.1 in Arizona Dairy Cattle.
- USDA. (2025). Biosecurity Recommendations for H5N1 in Dairy Operations.
- Characterization, health, productivity, and economic effects of highly pathogenic avian influenza hemagglutinin type 5 and neuraminidase type 1 outbreak in dairy cattle. (2025, April 1).
- The One Health challenges and opportunities of the H5N1 outbreak in dairy cattle in the United States. (2025, April 1).
Learn more:
- Silent Killer: Managing Asymptomatic H5N1 in Dairy Herds
Explore how 76% of H5N1-infected cows shed virus without symptoms, the economic impact on milk yield, and practical steps for early detection and biosecurity. - H5N1 Rages Through U.S. Dairy Industry While Canadian Farms Remain Virus-Free
A cross-border comparison highlighting why U.S. herds are vulnerable, how biosecurity lapses fuel outbreaks, and what Canada’s success teaches about prevention. - Biosecurity Battleground: How FARM Program Became Dairy’s Last Line of Defense Against H5N1
Discover how the National Dairy FARM Program’s science-based approach is transforming on-farm biosecurity and why proactive measures are now essential for survival.
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