Porcine circoviruses, including porcine circovirus 2 and porcine circovirus 3, have been associated with clinical syndromes in swine, resulting in significant economic losses. To better understand the epidemiology and clinical relevance of PCV2 and PCV3, the Swine Health Information Center helped fund a study to analyze diagnostic data collected between 2002 – 2023 for PCV2 and PCV3 from six US veterinary diagnostic laboratories. The research, led by Drs. Giovani Trevisan and Daniel Linhares at Iowa State University, aimed to evaluate the macroepidemiological trends of aggregated PCV2 and PCV3 PCR data over time, establish the real-time capacity to rapidly identify changes in PCV2 and PCV3 detection patterns, and investigate the association between PCV-positive PCR cycle threshold (Ct) values and confirmed PCV disease diagnosis in tissues.
Guilherme Cezar, the graduate student working with the team, reported a decrease in the percentage of PCV2-positive submissions after introducing a commercial PCV2 vaccine in 2006 and a resurgence in positivity after 2018. The 2018 resurgence was primarily in breeding herds associated with an increased number of processing fluid sample submissions. PCV3 detection was more frequent in adult/sow farms, while PCV2 was more frequently detected in the wean-to-market category. An interpretative Ct cutoff of 22.4 for PCV2 was associated with a high probability of confirming a PCV2 disease diagnosis through histopathology. For PCV3, the interpretative Ct cutoff with the highest performance was 26.7.
See the published study with references here. Visit the SDRS site here.
Porcine circovirus-associated disease (PCVAD) can cost producers an average of $3–4 per pig in economic losses, demonstrating the importance of monitoring and controlling these pathogens in swine farms. Due to the complexity of monitoring PCV clinical cases, there is a need to develop tools to reveal and monitor changing patterns of PCV2 and PCV3 detection in swine farms. This study used aggregated PCR cases reported by VDLs for PCV2 and PCV3 detection to unravel the megatrends of these viruses in the US over the last two decades.
PCV2 and PCV3 submissions from 2002 to 2023 were collated using distinct accession IDs. PCR results reported by the VDLs (positive, negative, suspect, or inconclusive) were used to establish the final case result in the database. For cases to be considered positive, at least one sample within the case was required to be PCR-positive. Alternatively, negative cases had to have negative PCR testing results across all samples. Suspect and inconclusive cases were reported according to each laboratory criteria.
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