Purpose:
To provide descriptive information on Acanthamoeba keratitis (AK) cases and analyze the geographical distribution within the Chicago–Gary–Kenosha Metropolitan area.
Methods:
All cases of AK diagnosed at the UIC Cornea Service between May 1, 2003 and November 30, 2005 were included in analysis. Cases were defined by confocal microscopy, histology and/or positive cultures. Descriptive statistics were calculated and exploratory analyses were performed to evaluate hypothesis strength that AK cases were unequally distributed throughout the Chicagoland area. County population data restricted to the same age as cases was extracted from U.S. Census 2000 data, and population data for all counties was age–standardized to Cook County population data. Poisson regression analysis using SAS (V8, NC) was used to estimate the age–standardized relative risk between number of AK cases and county of residence.
Results:
Forty–four AK cases were diagnosed between May 1, 2003 and November 30, 2005. Average AK case age was 29.6 ± 15.0 (SD; range = 13 – 70), 52.3% were male, and 93.2% used contact lenses. Estimated relative risk measures demonstrated increased risks for all counties relative to Cook, as shown in Table 1.
Conclusions:
Preliminary analysis of this pilot group of AK cases suggests further research is warranted to better understand the increase in cases and unusual geographical distribution. Geographical disparity investigation may suggest previously unknown risk factors and identify potential transmission vehicles associated with the increased AK diagnoses.
Keywords: Acanthamoeba • keratitis • clinical (human) or epidemiologic studies: risk factor assessment