National surveillance for the human ehrlichioses in the United States, 1997-2001, and proposed methods for evaluation of data quality.

This report describes the data accumulated during the first 5 years of national surveillance for the human ehrlichioses in the United States and territories, from its initiation in 1997 through 2001. Reported cases of human monocytic and granulocytic ehrlichiosis (HME and HGE) and cases of "other ehrlichiosis" (OE), where the agent was unspecified, originated from 30 states. As anticipated, most HME cases were from the south-central and southeastern United States, while HGE was most commonly reported from the northeastern and upper-Midwestern region. State-level incident reports of 487 HME, 1,091 HGE, and 11 OE cases were evaluated. The average annual incidences of HME, HGE, and OE per million persons residing in states reporting disease were 0.7, 1.6, and 0.2, respectively. The median ages of HME (53 yr) and HGE cases (51 yr) were consistent with published patient series. Most (> 57%) ehrlichiosis patients were male. The results suggest that national surveillance for the ehrlichioses, although imperfect in coverage, will help define endemic regions and may be useful for monitoring long-term trends. Although the data appear representative of the demographic profiles established for HME and HGE, rigorous evaluation of the system is required. Methods are proposed for evaluating the quality and representativeness of HME and HGE surveillance data, using well-established surveillance systems for Rocky Mountain spotted fever and Lyme disease.