The following data comprise exposure frequencies for sporadic culture-confirmed Salmonella cases that occurred in Minnesota from 2009 through 2015. Cases
were interviewed with a detailed questionnaire about exposures that occurred in the 7 days prior to their illness onset (http://mnfoodsafetycoe.umn.edu/wpcontent/uploads/2014/02/Salmonella-and-STEC-Interview-Form.pdf).
Epidemiologists can use these frequencies to estimate the background exposure rate in the population for a particular food item or other exposure and then use
this estimate in a binomial model comparison which is available in Epi Info 7 under StatCalc or as an excel spreadsheet at
This can be useful to quickly evaluate potential hypotheses during the hypothesis generation phase of an investigation prior to conducting a more resourceintensive
study method like a case-control study. Cases who were not interviewed, cases who reported international travel within the week prior to illness onset,
and outbreak-associated cases, regardless of the transmission route, were not included in these data.
Epidemiologists should carefully consider any potential biases arising from the use of Salmonella case exposure information to estimate background population
exposure rates. Using Salmonella cases to estimate the background exposure rate in the population will likely introduce bias away from the null hypothesis when
evaluating exposures that are risk factors for Salmonella. For example, the percentage of sporadic Salmonella cases that were exposed to a known Salmonella
risk factor such as eggs is potentially higher than the true background rate of exposure to eggs in the population. Epidemiologists should also consider if the food
item under evaluation has seasonal consumption patterns, or if consumption of the food varies by gender or age.
Another potential source for background exposure data is the FoodNet Population Survey Atlas of Exposures, 2006-2007
For more specific exposure frequencies to match the demographics of your current investigation, please contact Joshua.firstname.lastname@example.org