A longitudinal study on PRRSV detection in swine herds with different demographics and PRRSV management strategies

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) has been one of the major health-related concerns in the swine production industry. Through its rapid transmission and mutation, the simultaneous circulation of multiple PRRSV strains can be a challenge in PRRSV diagnostic, control and surveillance. The objective of this longitudinal study was to describe the temporal detection of PRRSV in swine farms with different production types and PRRS management strategies. Tonsil scraping (n = 344) samples were collected from three breeding and two growing herds for approximately one year. In addition, processing fluids (n = 216) were obtained from piglet processing batches within the three breeding farms while pen-based oral fluids (n = 125) were collected in the two growing pig farms. Viral RNA extraction and reverse-transcription quantitative PCR (RT-qPCR) were conducted for all samples. The sample positivity threshold was set at quantification cycle (Cq) of ≤ 37. Statistical analyses were performed using generalized linear modelling and post hoc pairwise comparisons with Bonferroni adjustments using R statistical software. The results suggested a higher probability of detection in processing fluids compared to tonsil scraping specimens [odds ratio (OR) = 3.86; p = .096] in breeding farms whereas oral fluids were outperformed by tonsil scrapings (OR = 0.26; p < .01) in growing pig farms. The results described herein may lead to an improvement in PRRSV diagnostic and surveillance by selecting proper specimens.

Detection of Multiple Lineages of PRRSV in Breeding and Growing Swine Farms

“…Three farrow-to-wean (Farm 1: 5,000 sows; Farm 2: 6,000 sows; and Farm 3: 2,500 sows, respectively), one wean-to-finish (Farm 4; 3,550 pigs), and one finisher farm (Farm 5; 2,800 pigs) were recruited and categorized based on their PRRSV infection statuses, as previously published ( 25 ). Farm 1 had the latest PRRS outbreak ~6 months prior to the first sampling event and was considered as a “previously infected” herd, i.e., no ongoing PRRSV exposures (e.g., natural exposure, live virus inoculation, vaccination) during the study period.…”

“…Although the diversity of PRRSV has been described at national and regional levels ( 22 – 24 ), the co-circulation of multiple variants within sampling events of production sites was barely investigated, especially by collecting multiple samples for single time points throughout a long period of time ( 25 ). Furthermore, reports on the association between PRRSV detection and its potential impact on reproductive and growth performance are rare.…”

Surveillance on swine farms using antemortem specimens

“…They were originally proposed as a sow surveillance tool for the detection of PRRSV, influenza A virus, porcine circovirus 2, porcine parvovirus, Mycoplasma hyopneumoniae and Salmonella enterica (Boettcher et al, 2010). This original observation has been supported by subsequent research (Campler et al, 2021;López et al, 2018;Vilalta et al, 2018).…”