title: The effect of HIV-related immunosuppression on the risk of tuberculosis transmission to household contacts.
abstract: BACKGROUND
  Coinfection with human immunodeficiency virus (HIV) may modify the risk of transmitting tuberculosis. Some previous investigations suggest that patients coinfected with HIV and tuberculosis are less likely to transmit infection, whereas others do not support this conclusion. Here, we estimated the relative risk of tuberculosis transmission from coinfected patients compared to HIV-negative patients with tuberculosis.
  
  
  METHODS
  Between September 2009 and August 2012, we identified and enrolled 4841 household contacts of 1608 patients with drug-sensitive tuberculosis in Lima, Peru. We assessed the HIV status and CD4 counts of index patients, as well as other risk factors for infection specific to the index patient, the household, and the exposed individuals. Contacts underwent tuberculin skin testing to determine tuberculosis infection status.
  
  
  RESULTS
  After adjusting for covariates, we found that household contacts of HIV-infected tuberculosis patients with a CD4 count ≤250 cells/µL were less likely to be infected with tuberculosis (risk ratio = 0.49 [95% confidence interval, .24-.96]) than the contacts of HIV-negative tuberculosis patients. No children younger than 15 years who were exposed to HIV-positive patients with a CD4 count ≤250 cells/µL were infected with tuberculosis, compared to 22% of those exposed to non-HIV-infected patients. There was no significant difference in the risk of infection between contacts of HIV-infected index patients with CD4 counts >250 cells/µL and contacts of index patients who were not HIV-infected.
  
  
  CONCLUSIONS
  We found a reduced risk of tuberculosis infection among the household contacts of patients with active tuberculosis who had advanced HIV-related immunosuppression, suggesting reduced transmission from these index patients.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health.
authors.forename: Chuan-Chin
authors.initials: CC
authors.lastname: Huang
authors.forename: Eric Tchetgen
authors.initials: ET
authors.lastname: Tchetgen
authors.forename: Mercedes C
authors.initials: MC
authors.lastname: Becerra
authors.forename: Ted
authors.initials: T
authors.lastname: Cohen
authors.forename: Katherine C
authors.initials: KC
authors.lastname: Hughes
authors.forename: Zibiao
authors.initials: Z
authors.lastname: Zhang
authors.forename: Roger
authors.initials: R
authors.lastname: Calderon
authors.forename: Rosa
authors.initials: R
authors.lastname: Yataco
authors.forename: Carmen
authors.initials: C
authors.lastname: Contreras
authors.forename: Jerome
authors.initials: J
authors.lastname: Galea
authors.forename: Leonid
authors.initials: L
authors.lastname: Lecca
authors.forename: Megan
authors.initials: M
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine / Q000008:administration & dosage; D018791:CD4 Lymphocyte Count; D002648:Child; D002675:Child, Preschool; D005191:Family Characteristics; D005260:Female; D015658:HIV Infections / Q000188:drug therapy / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology*; D015497:HIV-1 / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010568:Peru / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology / Q000276:immunology / Q000635:transmission* / Q000821:virology*; D055815:Young Adult
chemical_list: D001500:BCG Vaccine
keywords: CD4; HIV; contacts; infectiousness; tuberculosis infection