title: The United States Trypanosoma cruzi Infection Study: evidence for vector-borne transmission of the parasite that causes Chagas disease among United States blood donors.
abstract: BACKGROUND
  Screening US blood donors for Trypanosoma cruzi infection is identifying autochthonous, chronic infections. Two donors in Mississippi were identified through screening and investigated as probable domestically acquired vector-borne infections, and the US T. cruzi Infection Study was conducted to evaluate the burden of and describe putative risk factors for vector-borne infection in the United States.
  
  
  METHODS
  Blood donors who tested enzyme-linked immunosorbent assay repeat reactive and positive by radioimmunoprecipitation assay, and whose mode of infection could not be identified, were evaluated with a questionnaire to identify possible sources of infection and by additional serologic and hemoculture testing for T. cruzi infection.
  
  
  RESULTS
  Of 54 eligible donors, 37 (69%) enrolled in the study. Fifteen (41%) enrollees had four or more positive serologic tests and were considered positive for T. cruzi infection; one was hemoculture positive. Of the 15, three (20%) donors had visited a rural area of an endemic country, although none had stayed for 2 or more weeks. All had lived in a state with documented T. cruzi vector(s) or infected mammalian reservoir(s), 13 (87%) reported outdoor leisure or work activities, and 11 (73%) reported seeing wild reservoir animals on their property.
  
  
  CONCLUSIONS
  This report adds 16 cases, including one from the Mississippi investigation, of chronic T. cruzi infection presumably acquired via vector-borne transmission in the United States to the previously reported seven cases. The estimated prevalence of autochthonous infections based on this study is 1 in 354,000 donors. Determining US foci of vector-borne transmission is needed to better assess risk for infection.
authors.affiliation: Epidemic Intelligence Service, Office of Surveillance, Epidemiology, and Laboratory Services, and Division of Parasitic Diseases and Malaria, Center for Global Health, CDC, Atlanta, Georgia 30333, USA. pcantey@cdc.gov
authors.forename: Paul T
authors.initials: PT
authors.lastname: Cantey
authors.forename: Susan L
authors.initials: SL
authors.lastname: Stramer
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Townsend
authors.forename: Hany
authors.initials: H
authors.lastname: Kamel
authors.forename: Karen
authors.initials: K
authors.lastname: Ofafa
authors.forename: Charles W
authors.initials: CW
authors.lastname: Todd
authors.forename: Mary
authors.initials: M
authors.lastname: Currier
authors.forename: Sheryl
authors.initials: S
authors.lastname: Hand
authors.forename: Wendy
authors.initials: W
authors.lastname: Varnado
authors.forename: Ellen
authors.initials: E
authors.lastname: Dotson
authors.forename: Chris
authors.initials: C
authors.lastname: Hall
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Jett
authors.forename: Susan P
authors.initials: SP
authors.lastname: Montgomery
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D001782:Blood Donors / Q000706:statistics & numerical data*; D001803:Blood Transfusion / Q000706:statistics & numerical data; D014355:Chagas Disease / Q000097:blood / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission*; D015331:Cohort Studies; D004199:Disease Vectors; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008922:Mississippi / Q000453:epidemiology; D011795:Surveys and Questionnaires; D065227:Transfusion Reaction; D014349:Trypanosoma cruzi / Q000302:isolation & purification / Q000502:physiology; D014481:United States / Q000453:epidemiology; D055815:Young Adult