Figure 3

Physician visits for intestinal infectious diseases vs. precipitation accumulated over prior 2 weeks. Data from 1995 to 2003 inclusive; restricted to subpopulation (N = 4,868 physician visits and 117,543,309 person-days of observation) that received unfiltered surface water from North Shore Mountain reservoirs. a) Crude incidence rates per 100,000 person-years (top). b) Odds ratios adjusted for sex, age, calendar year, season, duration of residence in the Township, neighborhood household income quintile, drinking water disinfection, water system, sewage disposal, and land use (bottom)