The researchers found higher disease incidence among those living in higher SES census tracts.
To better understand the epidemiology of foodborne disease they examined incidence of Salmonella infection, Shiga toxin–producing E.coli (STEC) infection, and hemolytic uremic syndrome (HUS) by census tract–level socioeconomic status in the Connecticut Foodborne Diseases Active Surveillance Network site for 2000–2011.
An approach to identify demographic groups at high risk for bacterial foodborne infections is to examine incidence by area-based socioeconomic status (ABSES) measures.
Census tract–level poverty is a validated ABSES measure recommended by the Public Health Disparities Geocoding Project.
Addresses of case-patients were geocoded to census tracts and linked to census tract–level SES data.
Socioeconomic status and pathogen risk
Higher census tract–level SES was associated with STEC regardless of serotype; HUS; salmonellosis in people ≥5 years of age; and some Salmonella serotypes.
A reverse association was found for salmonellosis in children <5 years of age and for Salmonella Heidelberg.
“Efforts could be made to increase awareness among persons in high SES groups about their relatively high risk for STEC and Salmonella infection and about what actions they can take to reduce risk,” according to the study.
“Education campaigns about high-risk foods other than meat and about the importance of properly handling produce could be run in publications with a higher SES target audience.”
Salmonella and STEC are leading bacterial causes of foodborne illness and result in an estimated 1.2 million cases of gastrointestinal illness, ≈22,000 hospitalizations, and 400 deaths per year.
High SES not a risk but surrogate for high risk behaviour
Researchers said it is unknown whether findings in Connecticut are representative of STEC and salmonellosis incidence nationwide.
“The specific reasons behind SES-related risk for foodborne illness still need to be made clear, including for each of the leading Salmonella serotypes,” they said.
“For young children with salmonellosis, potential intervention points to reduce exposure inside and outside the home need to be identified. It remains unclear why children living in areas of higher SES are more at risk for STEC infection and HUS than children living in lower SES areas.
“These unanswered questions need to be investigated so that effective consumer-level interventions can be developed.”
Census tract-specific SES data for percentage of the population living below the federal poverty line was from the 2000 Census for case-patients for 2000–2005 and the 2006–2010 American Community Survey for case-patients for 2006–2011.
The researchers said several explanations have been suggested for why people in higher SES census tracts might have higher incidence of Salmonella and STEC infections and HUS, compared with persons in lower tracts.
A previous study in Michigan found Salmonella incidence increased with higher education and income levels.
A commonly proposed reason is those living in areas with higher census tract–level SES might have increased access to care and be more likely to submit specimens, regardless of disease severity, whereas those in lower socioeconomic groups might seek care or diagnostic testing only when illness is serious or prolonged but there is evidence against this.
“The more likely explanation for these findings is that SES affects the prevalence of known high-risk factors, such as international travel, consumption of high-risk food items, and eating at restaurants.
“That is, high SES itself is not a risk factor but rather a surrogate for certain high-risk behaviors.”
Source: Emerging Infectious Diseases – volume 21, number 9 September 15
“Socioeconomic Status and Foodborne Pathogens in Connecticut, USA, 2000–2011”
Authors: Bridget M. Whitney, Christina Mainero, Elizabeth Humes, Sharon Hurd, Linda Niccolai, and James L. Hadler