Disparities of Shigellosis Rates among California Children by Race/Ethnicity and Census Tract Poverty Level, 2000-2010.

BACKGROUND: We examined surveillance data for disparities in shigellosis rates among children by census tract (CT) poverty level and race/ethnicity in California. METHODS: We geocoded addresses of 9740 children younger than 15 years of age from 2000-2010 California shigellosis surveillance data and calculated incidence rate (IR) per 100,000 population by age group and race/ethnicity. We linked geocoded cases to 2006-2010 American Community Survey CT-level poverty data and used IR ratios to compare children in the most impoverished CTs with those in the least impoverished CTs. The contribution of socioeconomic inequalities to age-standardized racial and ethnic disparities was explored using Poisson regression. RESULTS: Per 100,000 population, shigellosis IR was highest among California children less than 5 years old (16.4) and of Hispanic ethnicity (15.2). The age-standardized IR was 22.3 per 100,000 person-years in CTs with more than 40% of the population below the poverty line and 4.1 per 100,000 person-years in CTs with less than 5% of the population below the poverty line, an IR ratio of 5.8 (95% confidence interval: 5.2, 6.5). CONCLUSIONS: Shigellosis rates among California children were highest among Hispanics and increased with CT poverty.