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A study was conducted by Dr. Cesar Corzo, Mariana Kikuti, and their colleagues from the University of Minnesota to provide cost-effective methods for active PRRSV monitoring that also consider animal welfare. Funded by the Swine Health Information Center, the study aimed to evaluate the accuracy of various post-mortem samples taken from piglets for disease detection in breeding herds. The sensitivity of PCR for detecting PRRSV was examined across six different sample types, including nasal, oral, and rectal swabs, saliva from the tongue tip, superficial inguinal lymph nodes, and intracardiac blood. Overall, the researchers concluded that oral swabs and lymph nodes exhibited the best diagnostic performance. Tongue tip saliva showed high sensitivity (92.2%) but had low specificity (53.9%) due to environmental contamination, making it less suitable for individual pig diagnosis.

PRRS continues to be a major health issue faced by swine herds in the United States. PRRS outbreaks have significant economic impacts and production losses, affecting a substantial portion of the breeding and growing herds. According to the Morrison Swine Health Monitoring Project, funded by the Swine Health Information Center, the estimated PRRS virus prevalence in breeding herds in the U.S. ranged from 20% to 40% between 2019 and 2023.

Traditionally, PRRS monitoring efforts in breeding herds have relied heavily on sample collection methods from live animals, including serum, oropharyngeal and nasal swabs at the individual level, as well as group-level oral fluids and environmental samples. Samples collected directly from live animals tend to exhibit higher analytical sensitivity compared to group or environmental samples. However, individual pig samples pose labor and logistical challenges, including issues related to workforce management, personnel safety, and animal welfare concerns.

Researchers in Europe have proposed a monitoring method using tongue tip samples from deceased piglet populations rather than processed fluids for PRRS. This method has been rapidly adopted in the U.S. as an additional sample type. This study aimed to determine the sensitivity of PRRSV detection through six post-mortem sample types taken from deceased piglets in breeding herds in the U.S.

The study utilized three Midwestern U.S. breeding herds that were in the process of eliminating PRRS after an outbreak. Farms utilizing PRRS-modified live virus vaccination protocols for sows or piglets were excluded from the study. The farms varied in size from 2,500 to 5,000 sows and all represented modern pig production, equipped with negative pressure air filtration systems year-round.

In each farm, a total of 30 and 60 samples were collected eight and twenty weeks post-PRRS outbreak, respectively. The post-mortem sample types included nasal swabs, oral swabs, rectal swabs, tongue tip saliva, superficial inguinal lymph nodes, and intracardiac blood. All samples were tested for PRRSV RNA using RT-PCR. Intracardiac serum was used as the gold standard to calculate the sensitivity, specificity, and predictive values of other post-mortem samples.

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Source: Tarım Haberleri