Factors Associated with Medical Care-Seeking and Stool Sample Submission for Diarrheal Illness, FoodNet, United States, 2018-2019.

Laboratory-based surveillance for enteric pathogens causing diarrhea is foundational for monitoring foodborne diseases in the United States. However, diarrheal illnesses are not always confirmed by laboratory testing, so estimates of the true number of illnesses must adjust for underdiagnosis, including underdiagnosis due to ill persons not seeking medical care or submitting a stool sample for laboratory testing. We assessed these factors among persons with an acute diarrheal illness who responded to the most recent Foodborne Diseases Active Surveillance Network (FoodNet) Population Survey (2018-2019). Multiple modes of administration (telephone, web-based) and multiple sampling frames were used to ask survey respondents in English or Spanish about diarrhea and other symptoms experienced in the 30 days before the interview and to ask if they had sought medical care or submitted a stool sample. Of 1018 respondents with an acute diarrheal illness, 22.0% had sought medical care and 4.7% submitted a stool sample. On multivariable analysis, older adults (aged 65 years and over), male respondents, and persons with a household income of ≥$40,000 per annum were significantly more likely to seek medical care, as were respondents reporting cough, fever, vomiting, recent international travel, or duration of diarrhea for ≥3 days. Older adults and persons with five or more loose stools in 24 h who sought medical care were significantly more likely to submit a stool sample. Ill respondents with a concurrent cough were less likely to submit a stool sample. Sociodemographic characteristics, symptoms, and international travel influence whether a patient with an acute diarrheal illness will seek care or submit a stool specimen. Accounting for these factors when analyzing surveillance data will likely produce more precise estimates of the true number of foodborne illnesses.