Academic journal article Journal of Environmental Health

The Potential for Community Exposures to Pathogens from an Urban Dairy

Academic journal article Journal of Environmental Health

The Potential for Community Exposures to Pathogens from an Urban Dairy

Article excerpt

Introduction

A number of excellent studies have examined the drift of bioaerosols from confined animal feeding operations (CAFOs) into the surrounding rural agricultural communities. Not all CAFO operations are located in rural environments, however. In many developing countries the line between agricultural and urban settings is blurring. As such, our study was conducted to examine a CAFO in an urban setting.

The animal husbandry industry has experienced significant production growth over the last few decades while at the same time the actual number of producers has decreased around the world (Speir et al., 2003). As countries become more affluent and human populations grow, the increased demand for livestock-derived food has led to increased industrialization of animal food production systems (Otte et al., 2007). Such industrialization has led to the increased utilization of CAFOs, where efficient animal husbandry has resulted in high animal population densities on small areas of land (Cole, Todd, & Wing, 2000).

The concentration of animals in relatively small areas creates conditions that are conducive to the transfer of pathogens within and between these populations, consequently increasing selection pressures and thus pathogen evolution (Otte et al., 2007). Emerging infectious disease events (EIDs) are dominated by zoonoses (60.3%) and 54% of EID events are caused by bacteria or rickettsia (Jones et al., 2008). The potential for organism transmission between food animals and human populations increases when they live in close proximity such as with the recent swine flu outbreaks.

CAFOs have been reported to release fungi, bacteria, antibiotic-resistant bacteria, and odor-emitting compounds into the surrounding air (Green, Gibbs, Tarwater, Mota, & Scarpino, 2006; Heederik et al., 2007; Mirabelli, Wing, Marshall, & Wilcosky, 2006; Radon et al., 2001). The negative health effects from airborne microorganisms released from CAFOs have been well documented. Among the most common negative effects are allergic and respiratory problems in both CAFO workers and people living in the surrounding areas (Donham et al., 2007; Green et al., 2006; Heederik et al., 2007; Liao & Luo, 2005; Mirabelli et al., 2006; Radon et al., 2001; Rule et al., 2005).

An additional public health concern is that the transference of antibiotic-resistant genes from the antibiotic-resistant microbial pool found in the CAFO environment may adversely affect the surrounding human population (Cole et al., 2000; Gilchrist et al., 2007; Sapkota, Ojo, Roberts, & Schwab, 2006). The CAFO workers appear to be the most important bridge between antibiotic-resistant bacteria in the CAFO and the surrounding community (Heederik et al., 2007; Jo & Seo, 2005; Mirabelli et al., 2006; Von Essen & Auverman, 2005).

As the human population increases and the community demographic changes, the physical space that separates the general community and CAFOs continues to be reduced. This close proximity of dense animal and human populations appears to augment the risk and transmissibility of zoonoses (Gilchrist et al., 2007; Otte et al., 2007). To mitigate the risks posed by CAFOs onto the community, regulatory entities in the U.S. (i.e., the U.S. Environmental Protection Agency) have developed guidelines for CAFO siting (e.g., setback distances) and have further defined the constraints under which CAFOs are to operate. The active enforcement of these guidelines is likely to reduce the health risks of CAFOs to the human population.

Developing countries such as Mexico have an increasing number of CAFOs but have not developed the regulatory guidelines necessary to mitigate the associated health risks (Speir et al., 2003). Internal demand within developing countries initially drove the development of their own CAFO infrastructure. Economic globalization has increased the number of CAFOs in countries like Mexico, where less stringent environmental guidelines have made them less expensive to operate. …

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