Integrating Spatial and Temporal Methods Into Surveillance for Shiga Toxin Producing Escherichia Coli (Stec) O157:H7 in Illinois

Abstract

Temporal and spatial clustering was identified for sporadic cases. Temporal patterns showed an increase in cases from late spring to early fall annually. Areas of decreased risk were found in the southern third of the state and the most urban areas surrounding Chicago. Risk factors associated with these high risk areas included increased number of cattle and cattle density. A decreased risk was associated with decreased number of beef cattle per farm. Using two statistical methods the space-time permutation and the space-time, we were able to identify most outbreaks that were previously identified by the public health department. In addition, these methods identified an outbreak not previously identified which was confirmed by epidemiologic and molecular data. Several other small probable outbreaks were also identified. These methods were found to be specific and did not identify numerous non-outbreaks as clusters.