First US commercial pseudorabies case since 2004 confirmed in Iowa, linked to Texas herd

Federal and state animal health officials have confirmed pseudorabies virus (PRV) antibodies in a small commercial swine facility in Iowa, marking the first detection in US commercial swine since the disease was eradicated from the industry in 2004.^1,2

The US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) National Veterinary Services Laboratories confirmed the detection on April 30, 2026, using enzyme-linked immunosorbent assay and latex agglutination testing.¹ The finding resulted from routine surveillance testing, not premovement surveillance.^1,2

Initial traceback identified 5 affected boars originating from an outdoor facility in Texas. Animals from that herd also tested positive for pseudorabies.^1,2 APHIS said it is working with officials in Iowa and Texas to expand traceback efforts and identify additional potential exposures.¹

First commercial detection in more than 2 decades

APHIS said this is the first known case of pseudorabies in commercial swine since 2004, when the disease was eradicated from the US commercial swine industry.¹ Commercial swine herds in all 50 states have historically been free of pseudorabies since that time.³

Although commercial herds have remained free of the disease, PRV is still present in US feral swine populations, which remain a source of potential exposure for domestic pigs.^1,3 According to the USDA, sporadic infections can occur in outdoor production systems or herds with outdoor access, especially where contact with feral swine is possible.^1,3

No clinical signs reported as response continues

According to Iowa State Veterinarian Jeff Kaisand, DVM, the affected boars showed no clinical signs and were identified through routine testing.² No additional pigs within the commercial facility tested positive, which he said suggested the animals were in the latent period during which they were likely not actively shedding virus and provided a “strong indication that there was no spread.”²

All animals from both the Iowa index herd and the noncommercial source herd in Texas have since been depopulated and properly disposed of, according to an APHIS response update.⁴ Cleaning and disinfection of the Iowa premises were completed on May 12, 2026.

As part of the outbreak response, animal health officials established 2-mile and 5-mile surveillance zones around the Iowa index herd. According to APHIS, movement restrictions within the 5-mile zone have since been lifted after all premises completed first-round testing with no additional detections.⁴ Movement restrictions remain in place within the 2-mile zone pending additional testing.⁴

Premises within the 2-mile zone, along with all exposed herds, must complete a second round of testing 30 to 60 days after cleaning and disinfection. APHIS said this testing is scheduled to occur between June 12 and July 11, 2026.⁴

The affected Iowa site remains under quarantine pending completion of a 30-day fallow period and negative results from second-round testing.⁴

Clinical signs and species affected

Pseudorabies is a contagious herpesvirus that primarily affects swine, which are the virus’ only natural hosts.^1,3 Although pigs are the primary host species, the virus can also infect cattle, sheep, goats, cats, dogs, and some wildlife species.³ USDA states humans are considered resistant to infection with PRV strains.³

Clinical signs in swine vary by age. In piglets, PRV may cause central nervous system signs, including tremors, seizures, hind-limb paralysis, recumbency, incoordination, walking in circles, coughing, sneezing, and death.³ In adult pigs, signs may include fever, coughing, pneumonia, reproductive failure, abortion, stillbirths, and occasional neurologic signs.³

In nonswine species, infection is typically fatal and may cause severe pruritus, muscle tremors, seizures, and death.³ These incidental hosts do not transmit the virus to other animals.³

Biosecurity remains a primary defense

There is no treatment for pseudorabies.³ Historical eradication efforts in US commercial swine relied on culling infected animals, vaccination with marker vaccines, movement restrictions, and preventing contact between domestic and feral swine.³

The USDA recommends biosecurity measures, including double fencing for outdoor herds, sourcing pigs from validated-qualified herds routinely tested for PRV, and implementing herd-level biosecurity plans.³

Although several vaccines are commercially licensed, their use is restricted because the US maintains a PRV-free commercial swine population.³ According to the USDA, vaccine use generally requires prior approval from APHIS and state animal health officials during confirmed outbreaks or emergency responses.³

Consumer safety and trade impact

USDA emphasized that the detection does not pose a risk to consumer health or affect the safety of the commercial pork supply.¹ However, officials noted there may be limited short-term impacts on exports of US swine and swine genetics.¹

APHIS said it will continue coordinating with state officials as traceback and surveillance efforts continue.¹

References

1. USDA confirms pseudorabies in swine herds in Iowa and Texas. USDA APHIS. April 30, 2026. Accessed May 19, 2026. https://www.aphis.usda.gov/news/agency-announcements/usda-confirms-pseudorabies-swine-herds-iowa-texas
2. Larkin M. For first time in two decades, pseudorabies detected in commercial swine herds. American Veterinary Medical Association. May 7, 2026. Accessed May 19, 2026. https://www.avma.org/news/first-time-two-decades-pseudorabies-detected-commercial-swine-herds
3. Pseudorabies. USDA APHIS. Updated May 13, 2026. Accessed May 19, 2026. https://www.aphis.usda.gov/livestock-poultry-disease/swine/pseudorabies
4. Pseudorabies response update: APHIS lifts movement restrictions within the 5-mile surveillance zone in Iowa. USDA APHIS. Accessed May 19, 2026. https://tinyurl.com/4a3petmy