title: A large community outbreak of blastomycosis in Wisconsin with geographic and ethnic clustering.
abstract: BACKGROUND
  Blastomycosis is a potentially life-threatening infection caused by the soil-based dimorphic fungus Blastomyces dermatitidis, which is endemic throughout much of the Midwestern United States. We investigated an increase in reported cases of blastomycosis that occurred during 2009-2010 in Marathon County, Wisconsin.
  
  
  METHODS
  Case detection was conducted using the Wisconsin Electronic Disease Surveillance System (WEDSS). WEDSS data were used to compare demographic, clinical, and exposure characteristics between outbreak-related and historical case patients, and to calculate blastomycosis incidence rates. Because initial mapping of outbreak case patients' homes and recreational sites demonstrated unusual neighborhood and household case clustering, we conducted a 1:3 matched case-control study to identify factors associated with being in a geographic cluster.
  
  
  RESULTS
  Among the 55 patients with outbreak-related cases, 33 (70%) were hospitalized, 2 (5%) died, 30 (55%) had cluster-related cases, and 20 (45%) were Hmong. The overall incidence increased significantly since 2005 (average 11% increase per year, P < .001), and incidence during 2005-2010 was significantly higher among Asians than non-Asians (2010 incidence: 168 vs 13 per 100 000 population). Thirty of the outbreak cases grouped into 5 residential clusters. Outdoor activities were not risk factors for blastomycosis among cluster case patients or when comparing outbreak cases to historical cases.
  
  
  CONCLUSIONS
  This outbreak of blastomycosis, the largest ever reported, was characterized by unique household and neighborhood clustering likely related to multifocal environmental sources. The reasons for the large number of Hmong affected are unclear, but may involve genetic predisposition.
authors.affiliation: Epidemic Intelligence Service, Scientific Education and Professional Development Program Office, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, MS C-09, Atlanta, GA 30307, USA. ige6@cdc.gov
authors.forename: Monika
authors.initials: M
authors.lastname: Roy
authors.forename: Kaitlin
authors.initials: K
authors.lastname: Benedict
authors.forename: Eszter
authors.initials: E
authors.lastname: Deak
authors.forename: Miles A
authors.initials: MA
authors.lastname: Kirby
authors.forename: Jena T
authors.initials: JT
authors.lastname: McNiel
authors.forename: Carrie J
authors.initials: CJ
authors.lastname: Sickler
authors.forename: Eileen
authors.initials: E
authors.lastname: Eckardt
authors.forename: Ruth K
authors.initials: RK
authors.lastname: Marx
authors.forename: Richard T
authors.initials: RT
authors.lastname: Heffernan
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Meece
authors.forename: Bruce S
authors.initials: BS
authors.lastname: Klein
authors.forename: John R
authors.initials: JR
authors.lastname: Archer
authors.forename: Joan
authors.initials: J
authors.lastname: Theurer
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Davis
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001758:Blastomyces / Q000302:isolation & purification*; D001759:Blastomycosis / Q000453:epidemiology* / Q000382:microbiology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D005006:Ethnicity; D005260:Female; D005843:Geography; D006801:Humans; D008297:Male; D008875:Middle Aged; D014922:Wisconsin / Q000453:epidemiology; D055815:Young Adult
keywords: Hmong; Wisconsin; blastomycosis; outbreak