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Updated: Apr 26, 2026
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Quantitative assessment of human MRSA risks from swine
Louis Anthony Tony Cox1, Douglas A Popken
1Cox Associates and NextHealth Technologies, 503 Franklin Street, Denver, CO, USA.
Abstract:
The public health community, news media, and members of the general public have expressed significant concern that methicillin-resistant Staphylococcus aureus (MRSA) transmitted from pigs to humans may harm human health. Studies of the prevalence and dynamics of swine-associated (ST398) MRSA have sampled MRSA at discrete points in the presumed causative chain leading from swine to human patients, including sampling bacteria from live pigs, retail meats, farm workers, and hospital patients. Nonzero prevalence is generally interpreted as indicating a potential human health hazard from MRSA infections, but quantitative assessments of resulting risks are not usually provided. This article integrates available data from several sources to construct a conservative (plausible upper bound) probability estimate for the actual human health harm (MRSA infections and fatalities) arising from ST398-MRSA from pigs. The model provides plausible upper bounds of approximately one excess human infection per year among all U.S. pig farm workers, and one human infection per 31 years among the remaining total population of the United States. These results assume the possibility of transmission events not yet observed, so additional data collection may reduce these estimates further.
Insights
Concerns about swine-associated methicillin-resistant Staphylococcus aureus (MRSA) transmitting to humans are widespread. This study estimates the risk, suggesting very low probabilities of MRSA infections in pig farm workers and the general population.
Area of Science:
- Public Health
- Infectious Diseases
- Microbiology
Background:
- Concerns exist regarding methicillin-resistant Staphylococcus aureus (MRSA) transmission from pigs to humans.
- Swine-associated MRSA (ST398) has been detected in various points of the transmission chain, from pigs to humans.
- Quantitative risk assessments for human health impacts are often lacking.
Purpose of the Study:
- To estimate the probability of human health harm from ST398-MRSA originating from pigs.
- To provide a conservative (upper bound) risk assessment for MRSA infections and fatalities in humans.
- To integrate available data for a quantitative evaluation of swine-to-human MRSA transmission risks.
Main Methods:
- Integrated available data from multiple sources.
- Constructed a probabilistic model to estimate risk.
- Calculated plausible upper bounds for human infections and fatalities.
Main Results:
- Estimated an upper bound of approximately one excess human infection per year among U.S. pig farm workers.
- Estimated an upper bound of one human infection per 31 years for the general U.S. population.
- Results are based on conservative assumptions and may be reduced with further data.
Conclusions:
- The quantitative risk of human health harm from swine-associated MRSA (ST398) is estimated to be low.
- Further data collection could refine these risk estimates.
- The study provides a framework for assessing risks associated with zoonotic pathogen transmission.
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