Exploring new methods for PRRS surveillance in pigs

By Scout Nelson

A recent descriptive study, shared on Bob Morrison’s Swine Health Monitoring Project, explores alternative sampling methods for Porcine Reproductive and Respiratory Syndrome (PRRS) surveillance. The study, led by a team of researchers including Arnaud Lebret, Valérie Normand, and others, focused on comparing the detection rate of PRRSV-1 in swine using various methods.

Conducted on a 210-sow farm in Brittany, France, the study included four consecutive batches with 30 litters each sampled the day before weaning. The researchers employed three methods: individual blood samples from piglets, Family Oral Fluid (FOF) using untreated cotton ropes, and Udder Wipes (UW) collected from the sows’ udders.

The results revealed significant findings. The concordance between serum samples and FOF was high, with a Cohen's kappa value of 0.84. However, serum samples showed significantly lower cycle threshold (Ct) values compared to FOF. Notably, UW failed to detect PRRSV in three out of four batches.

Pooling was tested only for serum and FOF samples, as UW showed limited positivity. Serum samples demonstrated a strong correlation between individual and pool Ct values. Conversely, FOF samples showed a marked decrease in detection when pooled, leading to misclassification of batches in some cases.

These findings underscore the potential and limitations of various sampling methods for PRRS surveillance in swine. While serum samples show promise, especially in individual testing, alternative methods like FOF need cautious interpretation, particularly when pooling samples. This study provides valuable insights for swine health professionals and farmers in designing more effective PRRS monitoring strategies.

Photo Credit: istock-srdjan-stepic