Oropharyngeal swabs offer alternative for PRRSV diagnosis in wean-age pigs
Taking oropharyngeal (OP) swabs — that is, samples from the tonsils — appears to be an effective alternative means for detecting porcine reproductive and respiratory syndrome virus (PRRSV) in wean-age pigs, especially when the prevalence of infection is high.1
PRRSV monitoring of weaned pigs on sow farms is usually based on serum samples, Kylie Glisson, a student at North Carolina State University’s College of Veterinary Medicine, explained at the 2017 meeting of the American Association of Swine Veterinarians. She and fellow investigators sought to find a less invasive and time-consuming testing method.
For their study, Glisson and colleagues chose OP swabbing because it targets the tonsillar area and has been used successfully to detect other pathogens such as influenza A virus of swine, Mycoplasma hyopneumoniae and porcine circovirus type 2.
They obtained samples from weaned pigs on two sow farms that had each been diagnosed with PRRSV infection 2 months before the start of the study. Both farms were visited twice, 2 weeks apart. The investigators sampled 100 pigs by inserting the swab in the back of the oral cavity and swabbing the soft palate vigorously for at least 5 seconds. They also collected serum on the same pigs for PRRSV testing in their study, sponsored by Zoetis.
The overall sensitivity with OP swabbing was nearly 83% based on true positives validated by the presence of virus in serum. Although the results suggest that OP swabbing is an effective, alternative means for PRRSV detection in weaned pigs when the infection prevalence is high, its use for PRRSV in chronically infected herds needs further study, Glisson cautioned.
She noted that the OP-swabbing technique has one other advantage: It’s easy to teach to farm employees.
1. Glisson K, et al. An evaluation of oropharyngeal swabbing as a diagnostic technique for the detection of porcine reproductive and respiratory syndrome virus (PRRSV) in weaned pigs. In: Proceedings of the 48th Annual Meeting of the American Association of Swine Veterinarians (February 25-28, 2017). Page 65.