Chengsheng Jiang, Kristi S. Shaw, Crystal R. Upperman, David Blythe, Clifford Mitchell, Raghu Murtugudde, Amy R. Sapkota, Amir Sapkota

Environment International

Published date October 1, 2015

Climate change, extreme events and increased risk of salmonellosis in Maryland, USA: Evidence for coastal vulnerability

  • Uses daily weather data from the National Climatic Data Center website for the 1960–2012 period, including daily maximum temperature (TMAX) and precipitation (PRCP) 
  • Computes county-specific 30 year baselines for a given calendar day using a 31 day window that centered around the particular calendar day
  • Identifies the 90th and 95th percentile values of PRCP and TMAX, referred to as Extreme Precipitation Threshold 90th percentile (EPT90) and Extreme Temperature Threshold 95th percentile (ETT95)
  • Compares calendar day specific PRCP and TMAX values for each county; assigns a value of “1” if they exceeded the thresholds, and “0” otherwise; and sums these “exceedance days” over the calendar month for each county during the 2002–2012 period
  • Investigates the relationship between EPT90 and ETT95 exceedance events and salmonellosis risk in all 24 Maryland counties for the 2002–2012 period
  • Finds the annual incidence of salmonellosis for Maryland ranged from 12.7 per 100,000 population in 2006 to 17.7 per 100,000 population in 2010
  • Observes a higher incidence of salmonellosis during Summer months followed by Fall, while the lowest incidence was observed during the Winter months
  • Observes a 4.1% increase in the risk of salmonellosis associated with a 1 unit increase in ETT95 exceedance (incidence rate ratio (IRR) 1.041; 95% confidence interval (CI): 1.013–1.069)
  • The findings related to extreme precipitation events were more consistent compared with those related to extreme temperature events
  • Observes a 5.6% increase in the risk of salmonellosis associated with a 1 unit increase in EPT90 exceedance (IRR 1.056; 95% CI: 1.035–1.078), but the increase in risk was not equal across all areas
  • Finds a one unit increase in EPT90 exceedance was associated with a 7.1% increase in the risk of salmonellosis in coastal counties (IRR 1.071; 95% CI: 1.044–1.099) compared wtih a 3.6% increase in non-coastal counties (IRR 1.036 95% CI: 1.017–1.054)