A recently published study conducted by Mark Schwartz and collaborators evaluated the feasibility of using air sampled from right outside the exhaust fans on finishing barns to detect PRRSV. The full article is available in open access on the journal’s website.
Methods
- Three wean-to-finish sites stocked with PRRSV-naive or PRRSV PCR negative pigs at placement
- 20 oral fluid ropes and 2-4 cotton cloths (air samples) collected every two weeks starting at 10 weeks or 3 weeks of age depending on the site.
- Samples were tested for PRRSV by RT-PCR
- No PRRSV vaccine was administered to the pigs during the study
Results
- The first PCR positive results were obtained between 4 to 6 weeks after the beginning of sampling.
- Air samples and oral fluid samples became positive at the same time.
- The probability to detect PRRSV in air samples was 26% when the Ct value was 30 in oral fluid samples.
- When the Ct value increased to 35, the probability to get a PCR positive result in air samples decreased to 7%
Abstract
Background: Diagnosis of porcine reproductive and respiratory syndrome virus (PRRSV) infections can be accomplished using various sample types and testing methods. The objective of this study was to evaluate the feasibility of using air emission samples to detect the onset of PRRSV type 2 infections in growing pigs.
Methods: Air emissions and oral fluid samples were collected from three grow-finish barns, stocked with PRRSV-negative pigs every 2 weeks for 14-20 weeks. All samples were assayed for PRRSV using RT-PCR.
Results: In all barns, PRRSV was initially detected in both air emissions and oral fluid samples at the same sampling event. Compared with oral fluids, air emissions collected subsequently yielded higher cycle threshold values and showed a lower likelihood of being RT-PCR positive.
Limitation: Sampling was limited to three grow-finish barns.
Conclusion: Air emission samples from pig barns are a biosecure and non-invasive sample type that is comparable to oral fluids for detection of the onset of PRRSV infection.