Guidelines for oral fluid-based surveillance of viral pathogens in swine

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(2020) 6:28

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Guidelines for oral fluid-based surveillance of viral pathogens in swine Alexandra Henao-Diaz* , Luis Giménez-Lirola, David H. Baum and Jeffrey Zimmerman

Abstract Recent decades have seen both rapid growth and extensive consolidation in swine production. As a collateral effect, these changes have exacerbated the circulation of viruses and challenged our ability to prevent, control, and/or eliminate impactful swine diseases. Recent pandemic events in human and animal health, e.g., SARS-CoV-2 and African swine fever virus, highlight the fact that clinical observations are too slow and inaccurate to form the basis for effective health management decisions: systematic processes that provide timely, reliable data are required. Oral fluid-based surveillance reflects the adaptation of conventional testing methods to an alternative diagnostic specimen. The routine use of oral fluids in commercial farms for PRRSV and PCV2 surveillance was first proposed in 2008 as an efficient and practical improvement on individual pig sampling. Subsequent research expanded on this initial report to include the detection of ≥23 swine viral pathogens and the implementation of oral fluid-based surveillance in large swine populations (> 12,000 pigs). Herein we compile the current information regarding oral fluid collection methods, testing, and surveillance applications in swine production. Keywords: Oral fluids, Surveillance, Viral diseases, ELISA, RT-PCR

Background Between 1968 and 2018, the worldwide swine inventory increased from 550 to 981 million pigs (+ 78%), with the most marked growth in the developing regions of the world, i.e., Africa + 504%, Asia + 137%, and South America + 59% [1]. Over the same period, albeit with regional variations, the majority of pig production moved from smaller, farrow-to-finish enterprises into larger, multisite production systems that are highly dependent upon the interchange of animals, people, equipment, and sundries between production sites; a process that connects farms and moves infectious agents between them [2, 3]. From an animal health perspective, larger pig populations combined with extensive interactions between production sites produce conditions that promote the circulation of infectious diseases within/between farms * Correspondence: [email protected] Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Veterinary Medical Research Institute, Iowa State University, Ames, Iowa 50011, USA

while simultaneously challenging our ability to control them [4, 5]. From a business perspective, these changes have limited our ability to avoid or control the economic impact of adverse disease events and, thus, place producers at greater financial risk [6]. In 1982, Calvin Schwabe, responding to the emerging problem of multi-factorial “production diseases”, noted that the simple causal models described by Koch and Pasteur no longer applied, i.e., predisposing causes, latency, carriers, opportunistic pathogens [4, 5]. To ada