Uncovering the Hidden Threat: Coronavirus Infections in Belgian Livestock – Is It Time to Worry?
Imagine a world where common viruses silently lurk in our farms, affecting animals without a single visible symptom in most cases. But what if these viruses aren't just harmless? Dive into this eye-opening study on bovine coronavirus (BCoV), porcine haemagglutinating encephalomyelitis virus (PHEV), and porcine respiratory coronavirus (PRCV) in Belgian cattle and pig herds. You might think coronaviruses are only a human concern, but here's where it gets controversial – these animal versions have been circulating widely, yet they're often overlooked in farming practices. And this is the part most people miss: their impact on productivity and health might be far greater than we realize, prompting debates on whether routine monitoring or vaccines should become standard.
Research
Open Access: https://www.springernature.com/gp/open-science/about/the-fundamentals-of-open-access-and-open-research
Published: 12 November 2025
Authors: Ruth M. Mumo¹, Stefaan Ribbens², Fabien Grégoire³, Sebastiaan Theuns⁴, Bart Pardon⁵, Kristien Van Reeth¹
¹Laboratory of Virology, Department of Translational Physiology, Infectiology and Public Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
²Laboratory and Logistics, Dierengezondheidszorg Vlaanderen, Industrielaan 29, Torhout, 8820, Belgium
³Laboratory and Diagnostics, Association Régionale de Santé et d’Identification Animales, Allée des Artisans 2, Ciney, 5590, Belgium
⁴PathoSense BV, Poortakkerstraat 41A, Gent, 9051, Belgium
⁵Calf Health Research Group, Clinic for Ruminants, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
BMC Veterinary Research volume 21, Article number: 659 (2025)
Cite this article: Mumo RM, Ribbens S, Grégoire F, et al. Seroprevalence of coronaviruses of cattle and pigs in Belgian herds. BMC Vet Res 21, 659 (2025). https://doi.org/10.1186/s12917-025-05115-x
Abstract
Background
In the realm of veterinary health, coronaviruses aren't just buzzwords from recent pandemics – they've been quietly affecting livestock for decades. This study shines a light on bovine coronavirus (BCoV), porcine haemagglutinating encephalomyelitis virus (PHEV), and porcine respiratory coronavirus (PRCV), three prevalent coronaviruses in cattle and swine. Despite their significance, these viruses are rarely tracked. Between December 2021 and March 2022, researchers gathered 2,639 bovine and 2,633 porcine blood samples from Belgian farms to assess current antibody levels against these pathogens. Samples were sorted by age and region, and tested using virus neutralization assays with fresh viral isolates.
Results
At the individual animal level, seroprevalence – that is, the percentage of animals with detectable antibodies indicating past or current infection – stood at 95.3% for BCoV, 96.2% for PHEV, and 76.4% for PRCV. For BCoV and PRCV, younger animals like calves and growing pigs showed lower rates compared to adults. Interestingly, areas with denser livestock populations had higher seroprevalence. In pigs, about 74.2% tested positive for both PHEV and PRCV simultaneously, suggesting these viruses often circulate together.
Conclusion
These three coronaviruses are firmly established in Belgian cattle and swine populations. Factors like age and livestock density play key roles in infection likelihood. PHEV and PRCV coexist in pig herds, raising questions about their transmission dynamics.
Peer Review reports: https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-025-05115-x/peer-review
Background
Coronaviruses form a family of viruses with single-stranded RNA genomes that can infect a broad array of animals. They're divided into four groups: alpha, beta, gamma, and delta coronaviruses.
BCoV, a beta coronavirus, was first identified in the United States back in 1972. It causes both digestive and respiratory issues in cattle, leading to conditions like calf diarrhea, winter dysentery, and bovine respiratory disease. To put this in simple terms, calf diarrhea can stunt growth by reducing weight gain – imagine a young calf not thriving due to constant sickness. Winter dysentery cuts into milk production, impacting farmers' incomes. Bovine respiratory disease, though not exclusively caused by BCoV, can lower growth rates, meat quality, and overall yield. The virus spreads via nasal secretions, feces, and even contaminated objects, making it highly contagious. High prevalence has been noted worldwide, from Africa and Asia to Europe, North and South America. Yet, no prior data existed on BCoV in Belgian cattle.
PHEV, another beta coronavirus, emerged in Canada in 1962 and Belgium in 1972. It primarily affects pigs through nasal and saliva transmission. In newborn piglets from unexposed mothers, it can cause severe symptoms like coughing, sneezing, nasal discharge, vomiting, diarrhea, wasting, and even neurological problems with high death rates. Older pigs rarely show signs, but the virus persists. PHEV has been detected globally, except for some regions. The last Belgian survey was in the late 1970s, leaving a gap in current knowledge.
PRCV, an alpha coronavirus, is part of the porcine respiratory disease complex – a mix of viruses and bacteria causing breathing problems in pigs, including PRRSV, PCV2, and Mycoplasma hyopneumoniae. It originated in Belgium in 1984 as a mutated form of transmissible gastroenteritis virus (TGEV), with a genetic deletion altering its focus from the gut to the lungs. Unlike TGEV, PRCV causes mild or no symptoms. Crucially, PRCV antibodies protect against TGEV due to shared surface proteins. Since its emergence, PRCV has spread widely, often alongside TGEV's decline, which has reduced its clinical and economic burden. However, recent Belgian data was missing.
Despite their importance in high-density farming areas like Belgium, these viruses' current status remains unknown in many places. This study aimed to fill that void with an age-stratified serological survey from December 2021 to March 2022.
Results
Seroprevalence of BCoV in Belgian Cattle
Every one of the 264 cattle farms sampled had at least one animal with BCoV antibodies, yielding a 100% herd-level seroprevalence (with a 95% confidence interval of 98.6–100%). After excluding three unusable samples, the total for individual analysis was 2,636. In 84.1% of farms, all animals tested positive, hinting at widespread exposure and easy transmission – think of it as the virus being like an unwelcome guest that never leaves the party. Overall, 95.3% of cattle had BCoV antibodies.
Regional differences were subtle: rates dipped to 90.0% in Flemish Brabant but rose to 98.9% in West Flanders, a region with more cattle. In Walloon areas, seroprevalence varied inversely with herd density – for example, lower in Walloon Brabant (90.0%) than Namur (97.3%). This points to animal density as a driver. Age also mattered: 6–12-month-olds had the lowest rate at 86.8%, while those over 2 years hit 99.4%. Antibody levels rose with age, from 127.3 in calves to 443.4 in adults (P < 0.0001), suggesting cumulative exposure builds stronger immunity over time.
Seroprevalence of PHEV in Belgian Swine
Analyzing 2,633 samples (with 3 excluded due to issues), only one farm out of 263 was PHEV-free, giving a 99.6% herd prevalence (95% CI: 97.9–100%). In 83.3% of farms, all pigs were positive. Rates were high: 97.8% in Antwerp and West Flanders, but dropped to 82.6% in Flemish Brabant (P < 0.0001), correlating with pig density. For age, fattening pigs (94.4%) and sows (97.8%) both showed high rates, with antibody levels lower in younger pigs (70.3 vs. 200.0, P < 0.05). This indicates age influences exposure.
Seroprevalence of PRCV in Belgian Swine
With 2,619 viable samples (14 contaminated), 4 out of 263 farms were negative, resulting in 98.5% herd prevalence (95% CI: 96.2–99.4%). Half the farms had over 80% positive pigs. Individually, 76.4% were seropositive, varying by region: higher in dense areas like West Flanders and Antwerp than in Flemish Brabant and Limburg. Fattening pigs were less likely positive than sows (P < 0.05), with lower antibody titers (Fig. 3). In 30 farms, no fattening pigs had antibodies, suggesting recent absence of the virus.
Cross-checking PHEV and PRCV in 2,619 samples revealed 74.2% positive for both, affecting 97.3% of farms – a clear sign of co-circulation.
Discussion
This comprehensive study explores BCoV, PHEV, and PRCV seroprevalence in Belgian livestock, linking it to region and age. Results confirm these viruses are enzootic, meaning they're constantly present in the population. Unlike many studies using ELISA, we measured neutralizing antibodies via virus neutralization assays for accuracy.
BCoV findings align with European reports (e.g., Italy, Poland, Sweden), indicating widespread circulation. Age-related increases in seropositivity and antibody levels make sense – older animals face more exposure opportunities. But here's where it gets controversial: provinces with higher densities showed elevated rates, supporting transmission through close contact, yet Hainaut's lower rate defied this, possibly due to unmeasured factors like management practices.
For PHEV, Belgian rates matched a 1979 study (95%), suggesting stable patterns, though deeper studies are needed. Age differences were minor, pointing to early immunity – maternal antibodies fade by 8–15 weeks, triggering active immunity. No recent outbreaks, likely due to protective maternal antibodies. Vaccines aren't available, so herd immunity is key.
PRCV results echoed 1990 data (98.2%), with stable epidemiology. Lower rates in young pigs indicate seasonal fluctuations, as seen in Belgium. PRCV's role in preventing TGEV resurgence is debated – it offers cross-protection, but TGEV levels remain low worldwide.
In pigs, PHEV's higher individual prevalence than PRCV raises questions: Is transmission easier, or are there more PHEV carriers? Comparative studies could unveil insights.
Vaccines for BCoV exist but weren't evaluated here. Without herd-type data, we couldn't assess system-specific risks, though high prevalence suggests density trumps production type.
Conclusion
As the largest European study on BCoV, PHEV, and PRCV using neutralization assays, this provides fresh data on their Belgian presence. All three are enzootic, with seropositivity tied to age and density. PHEV and PRCV co-circulate, but PHEV dominates individually, hinting at transmission differences.
Without detailed farm system info, further research on risk factors is essential. High rates imply production systems matter less, but is that true everywhere? And this is the part most people miss – with coronaviruses so entrenched, should we prioritize monitoring over intervention to prevent economic losses? What do you think? Do these findings change how you view livestock health, or are we overreacting to 'harmless' viruses? Share your thoughts in the comments – agree, disagree, or add your own experiences!
Materials and Methods
Sample Collection
Using a two-stage cluster design, farms were selected based on provincial animal distributions in Flanders and Wallonia. First, herds; then, animals stratified by age: 5 calves (6–12 months) and 5 cows (>1 year) per cattle farm; 5 fattening pigs (14–26 weeks) and 5 sows (>1 year) per pig farm. This balances exposure risks – younger animals show maternal antibody effects, adults cumulative ones. Samples came from disease surveillance programs, ensuring healthy animals. Cattle sera from winter screenings (Flanders) and IBR surveillance (Wallonia); pig sera from Aujeszky's program (Flanders). Collected December 2021–March 2022 by regional health associations.
Sample sizes: Designed for 50% prevalence, 5% error, 95% confidence, yielding 2,613 sera per virus. Totals: 2,639 cattle (264 herds), 2,633 pigs (263 herds).
Virus Neutralization Assays
Antibodies tested via VN assays against recent isolates: BCoV-Gent/PS-666/2020, PHEV-Gent/PS-412/2020, PRCV-Gent/PS-071/2020. Sera diluted serially, incubated with virus, then added to cell lines (HRT-18 for BCoV, RPD for PHEV, ST for PRCV). Positive if titer ≥4. Geometric means calculated for titers.
Virus Stock Production
Stocks propagated in appropriate cells, titrated via Reed-Muench method.
Control Antisera Production
Pigs vaccinated with isolates, bled post-boost. Ethical approval: Ghent University EC 2022-041.
Statistical Analysis
Logistic regression for seropositivity odds by age/province (R software, GraphPad). Non-parametric tests for titers. P<0.05 significant.
Data Availability
Raw data: https://doi.org/10.5281/zenodo.15727459
Abbreviations
BCoV: Bovine coronavirus
CPE: Cytopathic effects
HRT-18: Human rectal tumour cell 18
PHEV: Porcine haemagglutinating encephalomyelitis virus
PRCV: Porcine respiratory coronavirus
RPD: Rein de porc diploid
ST cells: Swine testes cells
TCID50: 50% tissue culture infectious dose
VN: Virus neutralisation
Acknowledgements
Thanks to Melanie Bauwens and Nele Dennequin for lab help.
Funding
Belgian Federal Public Service for Health, Food Chain Safety and Environment (RF 21/6347, CORUVA).
Author Contributions
RM and KVR designed, analyzed, wrote; SR/FG provided samples, reviewed; ST/BP reviewed.
Ethics Declarations
No approval needed; samples from surveillance programs.
Consent for Publication
N/A.
Competing Interests
None declared.
Publisher’s Note
Springer Nature neutral on maps/affiliations.
Rights and Permissions
Open Access under CC BY-NC-ND 4.0.
About this Article
Cite as above.
References
[Full list preserved, e.g., Stair EL, et al. Am J Vet Res. 1972;33(6):1147–56.]
