Evaluation of aggregate oral fluids for African swine fever real -time PCR diagnostics using samples collected on Romanian farms with an active outbreak

Authors: Chung, Chungwon; REMMENGA, MARTA - Animal And Plant Health Inspection Service (APHIS); MIELKE, SARAH - Animal And Plant Health Inspection Service (APHIS); BRANAN, MATTHEW - Animal And Plant Health Inspection Service (APHIS); MIHALCA, ANDREI - Institute Of Biological Research; BALABAN OGLAN, DAVID - Fartom Feed Additives Srl; SUPEANU, ALEXANDRU - National Sanitary Veterinary And Food Safety Authority (ANSVSA); FARKAS, ATTILA - Carthage Veterinary Services

Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2024
Publication Date: 8/13/2024
Citation: Chung, C.J., Remmenga, M.D., Mielke, S.R., Branan, M., Mihalca, A.D., Balaban Oglan, D.A., Supeanu, A., Farkas, A. 2024. Evaluation of aggregate oral fluids for African swine fever real -time PCR diagnostics using samples collected on Romanian farms with an active outbreak. Transboundary and Emerging Diseases. https://doi.org/10.1155/2024/9142883.
DOI: https://doi.org/10.1155/2024/9142883

Interpretive Summary: The analyses of data from three different farms with active outbreak of African Swine Fever showed no significant difference between the diagnostic sensitivities for real-time PCR using aggregate OF and pen-level determination using real-time PCR of individual blood samples when pens were sampled at varying levels. Although only a subset of pigs per pen were blood tested with varying subsets, the estimated within-pen prevalence values varied, and pen sizes were small, this study presents the first field evaluation on aggregate OF samples for ASFv real-time PCR diagnosis using farms with a current, naturally occurring ASF outbreak. Based on this promising results, the method of using aggregate OF should be recommended as a supplementary sample type for ASF diagnosis in addition to currently National Animal Health Laboratory Network-approved sample types, namely blood and spleen, tonsil, and lymph node tissues.

Technical Abstract: African swine fever (ASF), caused by African swine fever virus (ASFv), is a highly contagious disease of domestic and wild pigs with a mortality rate that can reach 100%. Continuous spread of the virus into ASF-free regions, including the Caribbean island of Hispaniola in 2021, is causing socio-economic burdens and presents a threat to food security. Pork producing countries, including the United States and Canada, are urgently looking for efficient tools for early detection to reduce spread of the virus in the event of an outbreak. Previous experimental infection studies evaluated the utility of aggregate porcine oral fluids as a sample type with a highly sensitive ASFv real-time PCR for individual blood and tissue-based diagnosis. In this study, real-time PCR with porcine oral fluids was further evaluated to better understand diagnostic performance using samples from three Romanian farms with an ongoing ASF outbreak. In this limited dataset using a Bayesian latent class model, no statistical difference in diagnostic sensitivity was found between the real-time PCR using aggregate oral fluids and the process of determining pen disease status by testing individual blood samples collected from a subset of pigs from the same pen. Known negative aggregate oral fluid samples from pigs in the United States had no occurrences of false positives, suggesting reliable diagnostic specificity of the sample matrix used for this study. Until results are produced from further studies with sufficient sample size, aggregate oral fluid testing using real-time PCR could cautiously be used as a supplementary sample type for ASF diagnosis alongside currently approved sample types, including blood and lymphoid tissues.