title: Outbreak of listeriosis among Mexican immigrants as a result of consumption of illicitly produced Mexican-style cheese.
abstract: BACKGROUND
  In 2000, an outbreak of listeriosis among Hispanic persons was identified in Winston-Salem, North Carolina. The objectives of the present study were to identify the source of, strains associated with, and risk factors for Listeria monocytogenes infection for patients affected by the outbreak.
  
  
  METHODS
  Microbiological, case-control, and environmental investigations were conducted. Participants in the case-control study were case patients who became infected with L. monocytogenes between 1 October 2000 and 31 January 2001 and control subjects who were matched with case patients on the basis of ethnicity, sex, age, and pregnancy status. All participants were residents of Winston-Salem.
  
  
  RESULTS
  We identified 13 patients, all of whom were Hispanic, including 12 females who were 18-38 years of age. Eleven case patients were pregnant; infection with L. monocytogenes resulted in 5 stillbirths, 3 premature deliveries, and 3 infected newborns. Case patients were more likely than control subjects to have eaten the following foods: fresh, unlabeled, Mexican-style cheese sold by door-to-door vendors (matched odds ratio [MOR], 17.5; 95% confidence interval [CI], 2.0-152.5); queso fresco, a Mexican-style soft cheese (MOR, 7.3; 95% CI, 1.4-37.5); and hot dogs (MOR, 4.6; 95% CI, 1.1-19.4). L. monocytogenes isolates recovered from 10 female case patients, from cheese bought from a door-to-door vendor, from unlabeled cheese from 2 Hispanic markets, and from raw milk from a local dairy had indistinguishable patterns on pulsed-field gel electrophoresis.
  
  
  CONCLUSIONS
  This outbreak of listeriosis was caused by noncommercial, fresh, Mexican-style cheese made from contaminated raw milk traced to 1 local dairy. We recommend educating Hispanic women about food safety while they are pregnant, enforcing laws that regulate the sale of raw milk and dairy products made by unlicensed manufacturers, making listeriosis a reportable disease in all states, routinely interviewing case patients, and routinely subtyping clinical L. monocytogenes isolates.
authors.affiliation: Epidemic Intelligence Service, Epidemiology Program Office, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA. pia@email.unc.edu
authors.forename: Pia D M
authors.initials: PD
authors.lastname: MacDonald
authors.forename: Robert E
authors.initials: RE
authors.lastname: Whitwam
authors.forename: Jackie D
authors.initials: JD
authors.lastname: Boggs
authors.forename: J Newton
authors.initials: JN
authors.lastname: MacCormack
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Anderson
authors.forename: Joe W
authors.initials: JW
authors.lastname: Reardon
authors.forename: J Royden
authors.initials: JR
authors.lastname: Saah
authors.forename: Lewis M
authors.initials: LM
authors.lastname: Graves
authors.forename: Susan B
authors.initials: SB
authors.lastname: Hunter
authors.forename: Jeremy
authors.initials: J
authors.lastname: Sobel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002611:Cheese / Q000382:microbiology*; D004196:Disease Outbreaks; D004641:Emigration and Immigration; D005260:Female; D005516:Food Microbiology / Q000592:standards*; D005517:Foodborne Diseases / Q000453:epidemiology*; D006801:Humans; D008088:Listeriosis / Q000453:epidemiology*; D008297:Male; D008800:Mexico; D009657:North Carolina / Q000453:epidemiology