Today, we are sharing a very recent publication from Dr. Mariana Kikuti in collaboration with the MSHMP team. Their project looked at the sensitivity of blood-soaked filter papers, blood-soaked swabs, oral swabs and tonsil oral scrubbings when compared to serum samples to detect PRRSV. The full manuscript is available in open-access on the journal’s website.
Methods
- 100 gilts (50 per farm), 25-28 weeks of age, inoculated with PRRSV as per farm protocol
- Samples were collected within 2 weeks of PRRSV exposure
- Study 1 samples: blood-soaked filter paper and swabs from the tail vein of the gilts
- Study 2 samples: Blood-soaked filter paper and swabs from the ear vein and tonsil oral scrubbings
- Serum samples and oral swabs were collected from all the gilts
- All samples except for the filter papers collected on tails (study 1) were tested by RT-PCR.
Results
- Blood-soaked filter papers from the tail vein were unsuccessful to collect enough blood for further testing.
- The ear vein was a better location than the tail vein to blood-soaked samples.
- In study 1, around 60% of tail blood swabs and oral swabs samples were PRRSV positive by RT-PCR compared to 100% for the serum samples.
- In study 2, 100% of the serum samples were positive whereas the sensitivity of tonsil scrubbings and blood-soaked filter paper from ear vein at 100% was statistically higher than of oral and ear blood swabs (p = 0.02), with sensitivities around 90%.
Abstract
Serum collection from swine is invasive and labor-intensive, which limits its practicality for disease surveillance and highlights the need for less invasive and cost-effective alternatives. In this study, we evaluated the sensitivity of blood-soaked filter papers (dry blood spots [DBS]), blood-soaked swabs, oral swabs (OS), and tonsil oral scrubbing (TOSc) when compared to serum for the detection of Porcine Reproductive and Respiratory Syndrome (PRRS) in viremic gilts under field conditions. Two studies were conducted with 50 recently inoculated gilts each. In study 1, tail pricking DBS and tail blood swabs were collected, with the sensitivity of the latter at 62.5% using serum as a reference. In study 2, PRRS RNA was detected in 100% of serum, TOSc, and DBS samples collected via ear pricking, yielding 100% sensitivity for both TOSc and DBS when compared to serum. However, OS and ear blood swabs showed ~90% sensitivity. Additionally, viral sequencing performed on serum and DBS from one gilt yielded identical sequences. While PRRS genetic material was successfully detected in all assessed specimens, sensitivity varied, with TOSc and ear prick DBS showing the strongest performance compared to serum. In terms of practicality of sample collection, OS ranked highest in ease and speed of collection, followed by TOSc, which required additional preparation time. Cost differences among sampling methods were described, with DBS as the most economical option at $0.44 per sample. This study supports the use of less invasive sampling methods for PRRS surveillance, particularly TOSc and DBS, which emerged as reliable and cost-effective alternatives for detecting the virus in recently inoculated gilts.