A recent examination by researchers from the University of Winchester (U.K.) and Griffith University (Australia) delves into the perils associated with keeping chickens and pigs in intensive farming settings and confined environments. The comprehensive review, featured in Frontiers in Veterinary Science, scrutinizes the heightened risks of zoonotic transmission, particularly from farm animals, notably pigs and poultry.
Zoonotic agents, comprising bacteria, fungi, parasites, protozoa, and viruses, are pivotal in this context. Among these agents, viruses, especially influenza viruses affecting the respiratory and digestive tracts, pose a substantial risk. Zoonotic transmission often occurs through direct contact with infected animal saliva or droppings or environmental contamination.
The prevailing conditions amplifying the risk of zoonosis globally include burgeoning human populations (exceeding 8 billion as of November 2022), extensive farmed chicken (25 billion) and pig (1 billion) populations, close human-animal proximity, suboptimal living conditions for farmed animals, the omnipresence and globalization of industrialized intensive animal farming (IIAF), IIAF-induced ecosystem disruptions due to land and resource demands, specific IIAF operation locations, and misconceptions about the risk levels associated with farmed animals.
Noteworthy historical instances of zoonoses involve outbreaks such as the Asian flu (H2N2 virus), Hong Kong flu (H3N2 virus), and swine flu (H1N1 virus). These instances underscore the potential for transmission from infected chickens and pigs to humans.
Compounding the challenge is the excessive use of antimicrobials in farmed animals globally. A study in PLoS Global Public Health (2023) reveals that farmed animals consume a staggering 73% of all antimicrobials, with projections indicating an 8% increase by 2030.
The researchers of this study focus on type A influenza viruses due to their prevalence. These viruses, categorized into various “H” and “N” subtypes, have the potential for antigenic shift and drift, leading to the emergence of new strains. The mixing of multiple influenza strains within host animals, termed mixing vessels, serves as a hotbed for genetic mutations and the emergence of novel strains, with significant implications for public health.
The mitigation strategies proposed in light of existing conditions involve biosecurity measures, vaccinations, public reduction in farmed animal consumption, restructuring of poultry and pig farming to enhance animal welfare through improved breeding practices, reduced antibiotic usage, and decreased animal housing density, and a phased-out approval process for new and expanded industrialized intensive animal farms. The researchers caution against the notion of a singular, straightforward solution and emphasize the multifaceted nature of risk mitigation in contemporary poultry and pig farming practices.
