Racial differences in reported Lyme Disease incidence

In the United States, the incidence of Lyme disease is considered to be dis proportionately high among Whites because of risk of exposure. For assessme nt of racial differences in Lyme disease incidence and the role of risk exp osure, incidence rate ratios (IRRs) for Lyme disease and its manifestations between Whites and African Americans in Maryland and in its focus of endem icity, the Upper Eastern Shore, were calculated. Calculations were based on reported cases of Lyme disease in Maryland during the years 1992-1996. The IRR for Lyme disease between Whites and African Americans was 6.3 (95% con fidence interval (CI): 5.0, 8.0), decreasing to 1.8 (95% CI: 1.2, 2.7) for the Upper Eastern Shore. Statewide, there was a significant difference betw een the White to African American IRR for erythema migrans and for Lyme dis ease-associated arthritis, at 17.7 (95% CI: 11.2, 27.8) and 2.3 (95% CI: 1. 7, 3.2), respectively. On the Upper Eastern Shore, the IRR for arthritis re versed, indicating higher incidence among African Americans than among Whit es: IRR = 5.7 (95% CI: 2.4, 13.9) for erythema migrans and IRR = 0.7 (95% C I: 0.4, 1.1) for arthritis. White patients were more likely to have erythem a migrans (risk ratio = 2.8, 95% C1: 1.9, 4.1) and less likely to have arth ritis than were African Americans (risk ratio = 0.4, 95% CI: 0.3, 0.5). Amo ng all patients, there was a significant negative association between arthr itis and erythema migrans. Although much of the racial disparity in inciden ce rates diminishes in a rural, endemic area, consistent with exposure risk being responsible for much of the variation, a difference remains. This ma y be due to failure to recognize early disease (erythema migrans) among Afr ican Americans, resulting in increased rates of late manifestations. Geogra phic spread of the disease warrants efforts to increase awareness of Lyme d isease and its manifestations among people of color and the health care pro viders who serve them.