title: Tuberculosis skin testing, anergy and protein malnutrition in Peru.
abstract: METHODS
  Malnutrition and intestinal parasites cause immunosuppression. This may cause false-negative tuberculin skin tests (TST) and failure to identify tuberculosis (TB) infection.
  
  
  OBJECTIVE
  To assess factors associated with TST positivity and anergy in disadvantaged communities in Peru.
  
  
  METHODS
  A study of 212 randomly selected adults: 102 in a rural Amazonian village and 110 shanty town residents in urban Lima.
  
  
  RESULTS
  Respectively 52% and 53% of urban and rural jungle populations were TST-positive. Using simultaneous tetanus and candida skin tests, 99% had at least one positive skin test. Generalised anergy was therefore rare, despite frequent intestinal parasitic infection, including 34% helminth infection prevalence in the jungle. TST positivity was associated with age (P = 0.001), known TB contact (P = 0.02) and poor household ventilation (P = 0.007). TST positivity was not significantly associated with crowding, reported past TB, single/multiple BCG vaccination, income, intestinal parasites, dietary factors, body mass index or body fat. Individuals with lower anthropometric body protein, as measured by corrected arm muscle area, were less likely to be TST-positive (P = 0.02), implying that protein malnutrition caused tuberculin-specific anergy.
  
  
  CONCLUSIONS
  These results identify the importance of household ventilation for community TB transmission and add to the evidence that protein malnutrition suppresses TB immunity, causing false-negative TST results.
authors.affiliation: Asociación Benéfica PRISMA, Lima, Peru.
authors.forename: T F
authors.initials: TF
authors.lastname: Pelly
authors.forename: C F
authors.initials: CF
authors.lastname: Santillan
authors.forename: R H
authors.initials: RH
authors.lastname: Gilman
authors.forename: L Z
authors.initials: LZ
authors.lastname: Cabrera
authors.forename: E
authors.initials: E
authors.lastname: Garcia
authors.forename: C
authors.initials: C
authors.lastname: Vidal
authors.forename: M J
authors.initials: MJ
authors.lastname: Zimic
authors.forename: D A J
authors.initials: DA
authors.lastname: Moore
authors.forename: C A
authors.initials: CA
authors.lastname: Evans
mesh_terms: D000293:Adolescent; D017635:Clonal Anergy; D015897:Comorbidity; D005188:False Negative Reactions; D006801:Humans; D007411:Intestinal Diseases, Parasitic / Q000453:epidemiology; D010568:Peru; D011502:Protein-Energy Malnutrition / Q000453:epidemiology / Q000276:immunology*; D014374:Tuberculin Test; D014376:Tuberculosis / Q000453:epidemiology / Q000276:immunology*; D014691:Ventilation