Disparities in Shigellosis Incidence by Census Tract Poverty, Crowding, and Race/Ethnicity in the United States, FoodNet, 2004-2014.

BACKGROUND

causes an estimated 500000 enteric illnesses in the United States annually, but the association with socioeconomic factors is unclear.

METHODS

We examined possible epidemiologic associations between shigellosis and poverty using 2004-2014 Foodborne Diseases Active Surveillance Network (FoodNet) data. cases (n = 21246) were geocoded, linked to Census tract data from the American Community Survey, and categorized into 4 poverty and 4 crowding strata. For each stratum, we calculated incidence by sex, age, race/ethnicity, and FoodNet site. Using negative binomial regression, we estimated incidence rate ratios (IRRs) comparing the highest to lowest stratum.

RESULTS

Annual FoodNet incidence per 100000 population was higher among children <5 years old (19.0), blacks (7.2), and Hispanics (5.6) and was associated with Census tract poverty (incidence rate ratio [IRR], 3.6; 95% confidence interval [CI], 3.5-3.8) and household crowding (IRR, 1.8; 95% CI, 1.7-1.9). The association with poverty was strongest among children and persisted regardless of sex, race/ethnicity, or geographic location. After controlling for demographic variables, the association between shigellosis and poverty remained significant (IRR, 2.3; 95% CI, 2.0-2.6).

CONCLUSIONS

In the United States, infections are epidemiologically associated with poverty, and increased incidence rates are observed among young children, blacks, and Hispanics.