Global review finds PRRSV remains widespread in pigs and wild boars: full analysis

A new systematic review and meta-analysis in Veterinary Sciences adds fresh global context to one of swine medicine's most persistent pathogens: porcine reproductive and respiratory syndrome virus. Reviewing serological studies in pigs and wild boars, the authors report that PRRSV remains widely distributed worldwide and that the strongest signals behind higher prevalence are tied to animal density and production intensity, not a single universal epidemiologic pattern. (mdpi.com)

That conclusion lands in a disease landscape veterinarians already know well. WOAH describes PRRS as a widespread viral disease of domestic pigs, first recognized in the United States in 1987, and says it remains one of the most important diseases in intensively raised pigs in North America and Europe, with growing importance in Asia. The organization also notes that PRRS is reportable under the WOAH framework, underscoring its continuing relevance for surveillance, trade, and disease reporting systems. (woah.org)

The new review is useful because it steps back from single-country snapshots and asks what the serology literature shows at a global level. According to the article summary, the study followed PRISMA methods and found that PRRSV seropositivity is broadly distributed, but unevenly documented. The authors highlight a practical limitation for the field: many countries still have little published seroprevalence data, which means the global map is informative but incomplete. That matters when veterinarians, regulators, and production systems try to benchmark disease pressure across regions or evaluate how representative published surveillance really is. (mdpi.com)

The wild boar angle is especially relevant for disease-surveillance readers. The paper notes that seropositive wild boars are often found in populations living near pig farms, suggesting exposure at the domestic-wild interface, but it stops short of framing wild boars as a clearly efficient long-term maintenance reservoir. That cautious interpretation is consistent with earlier literature, including a PubMed-indexed review concluding that the relationship between wild boar and domestic PRRSV infection appears weak, even though exchange between populations may occur. In other words, wildlife exposure is real, but the dominant epidemiologic engine still appears to be domestic swine production systems and the movements connected to them. (mdpi.com)

Industry context supports that view. Iowa State University reported in July 2024 that PRRS caused an estimated $1.2 billion per year in lost U.S. pork production from 2016 to 2020, with expert commentary from Derald Holtkamp emphasizing that veterinarians and producers are "still losing the battle" against the virus. Holtkamp pointed to frequent viral evolution, limited vaccine effectiveness, and the need for stronger biosecurity, especially as larger, more interconnected production systems create more opportunities for spread. (news.iastate.edu)

New strain-level work from China adds another layer to that global picture. In a separate Veterinary Sciences study, researchers isolated a European-like PRRSV-1 field strain, CDAC-SC2025, from a lung sample collected in Sichuan Province and characterized it by immunofluorescence, full-genome sequencing, and phylogenetic analysis. The isolate clustered within the BJEU06-1-like subgroup, was most closely related to HENZMD-10, showed no detectable recombination, and carried a three-amino-acid deletion in nsp2. Those details matter because they point to continued diversification and geographic spread of PRRSV-1 in China, where PRRSV-2 has historically drawn more attention.

The same study also helps translate genotype into clinical relevance. In newborn piglets challenged intranasally, CDAC-SC2025 caused fever, respiratory signs, growth retardation, and mortality, confirming that this emerging PRRSV-1 lineage is not just a sequencing curiosity. But its pathogenicity was lower than that of the comparison NADC30-like PRRSV-2 strain DJY: deaths occurred later, lesions were less severe, and histopathology showed more moderate damage rather than the more severe multisystemic injury seen with DJY. Both strains showed predominant viral loads in the lung and tonsils, with quantitative tissue differences. For practitioners, that is a useful reminder that "PRRSV" is not a single field reality; strain type and lineage can shape how disease presents and how aggressively it spreads through a system.

Why it matters: For veterinary professionals, this paper is less about a surprise finding than about sharpening priorities. A global seroprevalence review can't replace active herd monitoring, strain characterization, or production-system-specific risk assessment, but it does reinforce where pressure points remain: dense pig populations, replacement animal introductions, and uneven surveillance coverage. It also supports a balanced message on wildlife: clinicians and swine veterinarians should account for wild boar or feral swine exposure in regional risk assessments, while avoiding overstating their role relative to domestic pig movement and farm-to-farm transmission. In the U.S., that distinction is important because APHIS already treats feral swine as a disease concern in broader surveillance programs, even though PRRS is not the headline pathogen in those efforts. The China pathogenicity data strengthen the case for not treating PRRSV-1 and PRRSV-2 as interchangeable in control planning, especially as European-like PRRSV-1 strains continue to appear in Asian production settings. (mdpi.com)

There are also signs that PRRS remains active enough internationally to keep control programs on alert. A 2024 global swine disease surveillance report summarized WOAH notifications showing ongoing PRRS activity in Estonia, where positive pigs were identified during routine surveillance after animal introductions, again highlighting movement-associated risk. That kind of event mirrors the review's broader message: seroprevalence is shaped by management realities, not just pathogen biology. It also fits with the newer China data, which suggest that emerging lineages with distinct pathogenic profiles may further complicate already difficult control programs. (swinehealth.org)

What to watch: The next wave of work will likely center on filling country-level data gaps, teasing apart PRRSV-1 and PRRSV-2 epidemiology, and integrating serology with genomic and production data so veterinarians can better distinguish background exposure from active transmission risk. For practitioners, the practical watchpoint is whether surveillance programs and biosecurity protocols evolve fast enough to match a virus that continues to adapt. The recent Sichuan isolate is a good example of why that matters: even without detectable recombination, a BJEU06-1-like PRRSV-1 strain was capable of clinically meaningful disease, with lung and tonsil tropism and measurable mortality in newborn piglets. (mdpi.com)