Prev Vet Med. 2018 Nov 15;160:116-122. doi: 10.1016/j.prevetmed.2018.10.004. Epub 2018 Oct 10.
Development and validation of a scoring system to assess the relative vulnerability of swine breeding herds to the introduction of PRRS virus.
- 1
- Veterinary Diagnostic and Production Animal Medicine Department, Iowa State University, Ames, IA, United States; Laboratory of Veterinary Epidemiology (Epilab), Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
- 2
- Laboratory of Veterinary Epidemiology (Epilab), Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
- 3
- Veterinary Diagnostic and Production Animal Medicine Department, Iowa State University, Ames, IA, United States.
- 4
- Veterinary Diagnostic and Production Animal Medicine Department, Iowa State University, Ames, IA, United States. Electronic address: holtkamp@iastate.edu.
Abstract
Biosecurity is defined as the set of practices carried out to prevent the introduction and spread of infectious agents in a herd. These practices are essential in swine production, especially for highly infectious agents such as porcine reproductive and respiratory syndrome virus (PRRSv). Even with years of research and experience over the last three decades, PRRSv is still causing productivity losses and is the major health problem affecting the global swine industry. Despite knowledge of the various ways in which the virus can be transmitted from one herd to another (e.g. animals, semen, truck, air, and people), determining the most frequent ways in which the virus is transmitted in the field is difficult. A systematic approach to assess vulnerabilities at a herd level related to PRRSv transmission could help producers prioritize biosecurity practices to reduce or avoid the occurrence of outbreaks. The aim of this study was to develop a biosecurity vulnerability score that represents the relative vulnerability of swine breeding herds to the introduction of PRRSv. To create the biosecurity vulnerability score (outcome), a multi-criteria decision analysis methodology was used to rank and quantify biosecurity practices based on expert opinion. To validate the biosecurity vulnerability score, a survey of biosecurity practices and PRRS outbreak histories in 125 breed-to-wean herds in the U.S. swine industry was used. Data on the frequency of PRRS outbreaks was used to test the hypothesis that biosecurity vulnerability scores were different between farms that have a low incidence of PRRS outbreaks, compared to farms that have a high incidence. In the two databases used, the scores consistently showed that farms with higher scores have a higher frequency of PRRS outbreaks. In the first validation, farms that had never had an outbreak investigation before had a significant (p < 0.02) lower score (0.29; 0.21-0.37) when compared to farms that had 2 or more outbreaks (0.43; 0.39-0.46). In the second, the farms of the control group also had significant (p < 0.004) lower scores (0.30; 0.27-0.33) compared to the case group (0.35; 0.33-0.38). Also, the results suggest that events related to swine movements, transmission by air and water, and people movements should be prioritized. The biosecurity vulnerability scores may be useful to assess vulnerabilities on biosecurity protocols in order to reduce the frequency of PRRS outbreaks and may help producers and veterinarians prioritize investments in improving biosecurity practices over time.
KEYWORDS:
Biosecurity; Biosecurity vulnerability score; Carrying agents; PRRS; Risk events; Swine farms
