Multiple sclerosis prevalence and possible lead exposure.

This study was conducted to estimate the current prevalence of multiple sclerosis (MS) in Jefferson County, Missouri, USA, and to address community concerns about a perceived excess of MS around an active lead smelter. The study population consisted of the residents of Jefferson County, Missouri between 1998 and 2002. An aggressive MS case finding with capture-recapture analysis was used. The spatial clustering was examined using a spatial scan statistic. The capture-recapture analysis showed the case ascertainment to be 95%. The crude five-year period prevalence of MS in Jefferson County was 105 per 100,000 population (95% confidence interval [CI], 91-121), and 107 per 100,000 (95% CI, 95-119) when age-standardized to the 2000 U.S. population. No significant spatial clusters of MS cases were identified in the study area. The estimates of MS prevalence in Mid-western community of USA appeared to be comparable to estimates from other areas of similar latitude in the United States and Western Europe. The MS cases did not appear to cluster around the lead smelter.