Mounting evidence shows that porcine circovirus type 2 d(PCV2d) is now the predominant genotype circulating in U.S. swine herds and globally, and it is responsible for the majority of clinical PCVAD cases. This shift reinforces the importance of optimizing protection based on the genotype pigs are most likely to encounter in today’s production systems.1-3
Diagnostic data from the Iowa State University Veterinary Diagnostic Laboratory and global surveillance efforts confirm a steady shift in PCV2 genotype prevalence over time, with PCV2d now accounting for approximately 75% of U.S. diagnostic cases. Similar trends have been reported internationally, suggesting this shift is not temporary or regionally isolated.1-2
Beyond surveillance data, new research has strengthened the link between PCV2d and clinical disease expression. In a multistate investigation evaluating oral fluid surveillance alongside confirmed PCVAD cases, PCV2d was detected in nearly 77% of PCV2-positive production sites. More notably, sequencing of confirmed PCVAD cases revealed that over 82% were associated with PCV2d, compared to much lower detection rates for other genotypes. These findings suggest that PCV2d is not only widespread, but also a key driver of PCVAD, regardless of geography or production system.3
Disease rarely occurs in isolation
Complicating PCV2 control further is the reality that pigs rarely face a single pathogen challenge at a time. Coinfections — particularly with porcine reproductive and respiratory syndrome virus (PRRSV) — are common, and can significantly amplify clinical disease, mortality and performance losses.4–5
A controlled challenge study evaluating pigs exposed to both PCV2d and PRRSV provides insight into how vaccine genotype influences outcomes under complex disease pressure. In this study, pigs vaccinated with a PCV2d-based vaccine experienced the lowest mortality, fewer treatments and reduced viral replication compared to pigs vaccinated with a PCV2a-based vaccine, with both groups outperforming non-vaccinated controls.4–5
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