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Industrial Farm Animal Production

Communities living near animal feeding operations may face increased risk of certain health problems. These large, densely-packed livestock operations are a source of zoonotic pathogens that can spread through the environment to local communities, including through the use of animal manure to fertilize crop fields. They have also been shown to be a source of air pollution. To date, our research group has examined three health outcomes related to animal feeding operations in Pennsylvania. 

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) in the region has increased dramatically over the past decade, with over 4,000 cases during this period. Recently, community-associated infections (CA-MRSA) have surpassed healthcare-associated infections (HA-MRSA) in incidence. Joan Casey, a doctoral student at Johns Hopkins, completed her PhD dissertation research on this topic. Our research group made several interesting and novel observations which are summarized in three published, peer-reviewed manuscripts. We found: 1) the incidence of CA-MRSA increased by over 30 percent per year while that of HA-MRSA increased by five percent per year; 2) CA-MRSA cases now exceed HA-MRSA cases; 3) aspects of both the farms on which animals were raised and the crop fields to which manure was applied were associated with increased risk of MRSA infection and 4) certain molecular subtypes not previously associated with these animal operations were associated with human MRSA infections. We are currently investigating whether these animal feeding operations cause other health impacts.

Additionally, with funding from the Fisher Center Discovery Program in the Johns Hopkins School of Medicine, we have investigated two infectious disease risks associated with living near large, densely-populated poultry operations. Considering poultry carry zoonotic bacteria (for example, Campylobacter, E. coli, Salmonella) that can cause gastroenteritis in humans, one study assessed whether closer residential proximity to more and larger poultry operations is associated with diarrheal illness, taking weather-related variables like precipitation into account (publication pending). As a source of air pollution, animal feeding operations can also compromise the respiratory health of individuals living near them, potentially increasing the risk of pneumonia. Thus, in a second study, we are examining whether proximity to poultry operations is related to diagnosis with community-acquired pneumonia. 


  • Poulsen MN, Pollak J, Sills DL, Casey JA, Nachman KE, Cosgrove SE, Stewart D, Schwartz BS. High-density poultry operations and community-acquired pneumonia in Pennsylvania. Environmental Epidemiology 2018.
  • Poulsen MN, Pollak J, Sills DL, Casey JA, Rasmussen SG, Nachman KE, Cosgrove SE, Stewart D, Schwartz BS. Residential proximity to high-density poultry operations associated with campylobacteriosis and infectious diarrhea. International Journal of Hygiene and Environmental Health, 2018; 221: 323-333.
  • Rasmussen SG, Casey JA, Bandeen-Roche K, Schwartz BS. Proximity to industrial food animal production and asthma exacerbations in Pennsylvania, 2005-2012. Int J Environ Res Public Health 2017; 14: E362, 9 pages.
  • Casey JA, Shopsin B, Cosgrove SE, Curriero FC, Nachman KE, Rose H, Schwartz BS. Molecular characterization of MRSA infection and association with high-density livestock production in Pennsylvania, USA. Environ Health Perspect 2014; 122: 464-70. 
  • Casey JA and Schwartz BS. Swine livestock production as a risk factor for community associated MRSA in Pennsylvania. Alliance for the Prudent Use of Antibiotics (APUA) newsletter, 2013; 31: 9-12. 
  • Casey JA, Curriero FC, Cosgrove SE, Nachman KE, Schwartz BS. High-density livestock operations, crop field application of manure, and risk of community-associated methicillin-resistant Staphylococcus aureus infection in Pennsylvania. JAMA Intern Med 2013; 173: 1980-90.
  • Casey JA, Stewart WF, Cosgrove SE, Pollak J, Schwartz BS. A population-based study of the epidemiology and clinical features of methicillin-resistant Staphylococcus aureus infection in Pennsylvania 2001-2010. Epidemiology & Infection 2013; 141: 1166-79. 
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