Socioeconomic Status and Campylobacteriosis, Connecticut, USA, 1999–2009

Reported changes in health-related behaviours in Chinese urban residents in response to an influenza pandemic. To the Editor: Campylobacter is the second most common bacterial cause of foodborne gastrointestinal illnesses in the United States and the leading cause of these illnesses in Connecti-cut (1). It is also the leading identifiable cause of Guillain-Barré syndrome in the United States and all industrialized countries in which it has been studied (2). According to the Foodborne Disease Active Surveillance Network (FoodNet), campylobacteriosis incidence in the United States is increasing (1). Clarification of the epidemiology of campylobacteriosis is needed to control and prevent infection. Socioeconomic status (SES) measures have not been explored in the United States as determinants for Campylobacter infection. Although individual SES measures are not routinely collected in FoodNet, street address of patient residence is. Following the recommended method of the Public Health Disparities Geocoding Project (3), we used census tract–level poverty as an SES measure for analysis. We attempted to geocode patient residences for all campylobacteriosis cases reported in Connecticut during 1999–2009 and to categorize them into 4 groups on the basis of percentage of residents in the census tract living below the federal poverty line: 0–<5%, 5%–<10%, 10%–<20%, and >20%. The average annual age-adjusted (on the basis of 2000 US Census data for Connecticut) incidence rate was calculated for each of 4 census tract-level neighborhood SES (i.e., neighborhood poverty) categories for all years combined and for 3 periods In addition, age group-specific rates were calculated for case-patients in the 4 SES categories. We used the χ 2 test for trend to assess the statistical significance of observed gradients of incidence across SES levels. We geocoded 5,708 (95.9%) of the 5,950 campylobacteriosis cases reported during 1999–2009 to census tract level. The average annual crude incidence rate was 15.9 per 100,000 population; average age-specific incidence ranged from 9.4 in the 10–19-year age group to 18.1 in the >50-year age group. We found a strong dose-response relationship between higher campylobacteriosis incidence and higher neighborhood SES. Average annual age-adjusted incidence was for the highest SES group (0–<5% below poverty) (p<0.001 byχ 2 for trend). A strong SES gradient was also consistent and significant (p<0.001 by χ 2 for trend) for each of the 3 periods. Incidence within age groups by neighborhood SES level is shown in the Figure. For all age groups >10 years, incidence of campylobacte-riosis increased as neighborhood SES increased (p<0.001 for …