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

Jackson, Rebecca MPH*; Smith, Daniel DrPH; Tabnak, Farzaneh PhD, MS; Vugia, Duc MD, MPH

The Pediatric Infectious Disease Journal: August 2015 - Volume 34 - Issue 8 - p 843–847
doi: 10.1097/INF.0000000000000746
Original Studies

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.

Supplemental Digital Content is available in the text.

From the *Environmental Health Investigations Branch, Occupational Health Branch, and Infectious Diseases Branch, California Department of Public Health, Richmond, California.

Accepted for publication February 18, 2015.

R.J. was supported in part by an appointment to the Applied Epidemiology Fellowship Program administered by the Council of State and Territorial Epidemiologists (CSTE) and funded by the Centers for Disease Control and Prevention Cooperative Agreement Number 5U38HM000414-5. The authors have no conflicts of interest to disclose.

Rebecca Jackson is currently at California Department of Industrial Relations, 1515 Clay Street, Oakland, CA 94612.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (

Address for correspondence: Duc Vugia, MD, MPH, Infectious Diseases Branch, California Department of Public Health, Richmond, CA 94804. Email:

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