Date

9-2014

Document Type

Thesis

Degree Name

M.P.H.

Department

Dept. of Public Health & Preventive Medicine

Institution

Oregon Health & Science University

Abstract

Background:

The climate of Oregon is highly variable and ranges from a temperature rainforest to the high desert. The average annual temperature in the Pacific Northwest has increased 1.5ºF since 2003. There has been a 14% increase in precipitation during this time as well. As the climate of Oregon changes, meteorological variability may have a significant impact on the incidence of foodborne disease and can affect food safety for the population through pathways of temperature and precipitation, extreme weather events, ocean warming and acidification, and changes in transport pathways.

Methods:

Temperature, precipitation, and ENSO data were obtained from the National Oceanic Atmospheric Administration. Campylobacter and Salmonella case data were obtained from a database managed by the Oregon State Public Health Division. Multiple exclusion criteria were applied to ensure that the cases included in this study were sporadic cases without travel outside of Oregon during their exposure period. Poisson regression with the log population as the offset was used to determine if there were associations between monthly meteorological variables (mean monthly maximum and minimum temperature, highest recorded monthly maximum and minimum temperature, lowest recorded monthly maximum and minimum temperature, precipitation and snow depth) and reported Salmonella and Campylobacter infections. Case data and meteorological data were merged on the regional and county level so generalized estimating equations were used to control for geographic correlation.

Results:

We found that increased temperature was associated with higher rates of both reported Campylobacter and Salmonella infections in Oregon. The mean monthly minimum temperature was associated with the highest increase in the rate of reported Campylobacter (rate ratio: 2.9%, 95% CI: 2.5%, 3.4%) and Salmonella (rate ratio: 3.0%, 95%CI: 2.1%, 3.4%) infections. We also found that precipitation was inversely associated with the rate of reported Campylobacter and Salmonella in Oregon. However, these associations between temperature and precipitation did not remain after adjusting for seasonal trends. An opposing effect was seen between El Niño and La Niña events. El Niño events were associated with higher rates of reported Campylobacter and Salmonella infections, while La Niña events were associated with lower rates of reported Campylobacter and Salmonella infections. We found that the opposing effect of El Niño and La Niña persisted even after adjusting for seasonal trends.

Conclusion:

As reported in analysis of data for other regions, temperature and precipitation in Oregon were associated with incidence of enteric infections from Campylobacter and Salmonella. The associations of these meteorological factors were strongly correlated to season. On a longer temporal cycle, El Niño and La Niña events demonstrated opposing effects on the rates of reported Campylobacter and Salmonella illness in Oregon. El Niño events were associated with higher rates of reported illness and La Niña events were associated with lower rates of reported illness. These findings suggest that the incidence of enteric illness attributable to Campylobacter and Salmonella in Oregon are influenced by temperature and precipitation. Because these meteorological factors are expected to change with climate trends, public health planning should incorporate food safety interventions into climate change adaptation efforts.

Identifier

doi:10.6083/M4RB7391

School

School of Medicine

Available for download on Tuesday, September 19, 2017

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