Can family oral fluids improve PRRSV surveillance before weaning?

Problem: Detecting low-prevalence PRRSV infection in breeding herds can require sampling many piglets, creating a need for litter-level surveillance methods.

Methods: Researchers compared family oral fluids (FOF) with individual serum samples from 2,177 piglets in 199 litters across six farms, using RT-qPCR and modeling the probability of detection according to within-litter prevalence, parity and litter size.

Takeaway 1: Thirty-four of 199 litters (17.1%) had at least one viremic piglet, while 28 of 199 (14.1%) were FOF-positive.

Takeaway 2: The probability of a positive FOF rose sharply with within-litter prevalence: 3.5%, 35.1%, 88.8%, 99.2% and >99.9% at prevalences of 10%, 20%, 30%, 40% and 50%, respectively.

Takeaway 3: First-parity litters and litters of ≤11 piglets had higher probabilities of FOF positivity, suggesting risk-based targeted sampling may improve surveillance; however, a negative FOF does not guarantee absence of PRRSV.