One World, One Health: The Threat of Emerging Swine Diseases. A North American Perspective

Abstract

Summary The predicted expansion of global livestock populations to meet the food and fibre demands of the growing human population raises numerous concerns, including the implications for disease emergence. The evolution of animal production in developed countries has been marked by substantial reduction in farm numbers with correspondingly larger herd sizes, specialization of enterprises, concentration or ownership and vertical integration. Innovations in the structure and operations of swine production have been largely driven by efforts to improve swine health, and the impact of several important swine diseases has declined. Productivity in swine production and the safety of pork products have increased markedly. The most significant emerging infectious diseases of pigs over the last decades have been highly host‐specific viruses rather than multihost pathogens. While some bacterial pathogens of pigs have increased in importance in modern systems, improved management systems and biosecurity have enabled herd sizes to increase without negative impact on swine health. The most vulnerable scenario for disease emergence in swine, particularly for zoonotic agents, may be rapid expansion and intensification of swine industries in developing countries without incorporating the stringent biosecurity measures and veterinary oversight that have helped maintain the health and productivity of large herds in North America. Factors that may influence disease emergence in the long term include regulatory measures (particularly related to antimicrobial use), genetics and feeding practices.

The dilemma of rare events: Porcine epidemic diarrhea virus in North America

“…In the 'one health' era, interspecies transmission of pathogens holds the center stage of scientific and public interest. However, the intensive systems of single species food animal production which now predominate in developed countries are arguably more likely to favor the emergence of host specific pathogens (Davies, 2012;Harding, 2014). A striking parallel in the histories of PRRS, PCV2, and PEDV, is that considerable periods passed from the time the viruses were first found in swine until the advent of pandemics of severe disease.…”

“…Against this vast, diverse and dynamic backdrop of viral evolution in pigs, the emergence of 3 highly pathogenic viruses over 25 years can be considered extremely rare events, but probably provides a reasonable estimate of what we should anticipate into the future. It is also likely that features of modern swine production including globalization, intensification and extensive movement of pigs have contributed to the success of these agents in expanding their geographic ranges (Murtaugh, et al, 2010;Ayudhya, et al, 2012;Davies, 2012).…”

“…) into farms. This reality is already reflected in the substantial investments in biosecurity in larger swine herds in the USA, that have underpinned the transition to larger herd sizes without substantial negative impact on swine health (Davies, 2012;Alonso et al, 2013).…”

Zoonotic Diseases of Swine: Food-borne and Occupational Aspects of Infection

“…However, outbreaks of host specific lethal zoonoses have occurred in industrialized nations as well (Davies 2012). It is plausible that a dramatic change in swine industry demographics in recent decades without adequate biosecurity may have served as a tonic for the emergence of swine zoonosis (Davies 2012). Zoonotic diseases impose significant economic burden with increased morbidity and mortality globally.…”

“…Densely populated South East Asia is the epicenter of emergence of novel zoonotic diseases due to inter-species transmission. However, outbreaks of host specific lethal zoonoses have occurred in industrialized nations as well (Davies 2012). It is plausible that a dramatic change in swine industry demographics in recent decades without adequate biosecurity may have served as a tonic for the emergence of swine zoonosis (Davies 2012).…”