title: Spatial clustering by disease severity among reported Rocky Mountain spotted fever cases in the United States, 2001-2005.
abstract: Rocky Mountain spotted fever (RMSF) occurs throughout much of the United States, ranging in clinical severity from moderate to fatal infection. Yet, little is known about possible differences among severity levels across geographic locations. To identify significant spatial clusters of severe and non-severe disease, RMSF cases reported to Centers for Disease Control and Prevention (CDC) were geocoded by county and classified by severity level. The statistical software program SaTScan was used to detect significant spatial clusters. Of 4,533 RMSF cases reported, 1,089 hospitalizations (168 with complications) and 23 deaths occurred. Significant clusters of 6 deaths (P = 0.05, RR = 11.4) and 19 hospitalizations with complications (P = 0.02, RR = 3.45) were detected in southwestern Tennessee. Two geographic areas were identified in north-central North Carolina with unusually low rates of severity (P = 0.001, RR = 0.62 and P = 0.001, RR = 0.45, respectively). Of all hospitalizations, 20% were clustered in central Oklahoma (P = 0.02, RR = 1.43). Significant geographic differences in severity were observed, suggesting that biologic and/or anthropogenic factors may be impacting RMSF epidemiology in the United States.
authors.affiliation: Epidemic Intelligence Service, Office of Workforce and Career Development, Centers for Disease Control and Prevention, Atlanta, GA 30030, USA.
authors.forename: Jennifer Zipser
authors.initials: JZ
authors.lastname: Adjemian
authors.forename: John
authors.initials: J
authors.lastname: Krebs
authors.forename: Eric
authors.initials: E
authors.lastname: Mandel
authors.forename: Jennifer
authors.initials: J
authors.lastname: McQuiston
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002487:Centers for Disease Control and Prevention, U.S.; D016000:Cluster Analysis; D018563:Disease Notification; D005843:Geography; D006760:Hospitalization / Q000706:statistics & numerical data; D009825:Oklahoma / Q000453:epidemiology; D012373:Rocky Mountain Spotted Fever / Q000188:drug therapy / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D014481:United States / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents