title: Prevalence of latent and active tuberculosis among dairy farm workers exposed to cattle infected by Mycobacterium bovis.
abstract: BACKGROUND
  Human tuberculosis caused by M. bovis is a zoonosis presently considered sporadic in developed countries, but remains a poorly studied problem in low and middle resource countries. The disease in humans is mainly attributed to unpasteurized dairy products consumption. However, transmission due to exposure of humans to infected animals has been also recognized. The prevalence of tuberculosis infection and associated risk factors have been insufficiently characterized among dairy farm workers (DFW) exposed in settings with poor control of bovine tuberculosis.
  
  
  RESULTS
  Tuberculin skin test (TST) and Interferon-gamma release assay (IGRA) were administered to 311 dairy farm and abattoir workers and their household contacts linked to a dairy production and livestock facility in Mexico. Sputa of individuals with respiratory symptoms and samples from routine cattle necropsies were cultured for M. bovis and resulting spoligotypes were compared. The overall prevalence of latent tuberculosis infection (LTBI) was 76.2% (95% CI, 71.4-80.9%) by TST and 58.5% (95% CI, 53.0-64.0%) by IGRA. Occupational exposure was associated to TST (OR 2.72; 95% CI, 1.31-5.64) and IGRA (OR 2.38; 95% CI, 1.31-4.30) adjusting for relevant variables. Two subjects were diagnosed with pulmonary tuberculosis, both caused by M. bovis. In one case, the spoligotype was identical to a strain isolated from bovines.
  
  
  CONCLUSIONS
  We documented a high prevalence of latent and pulmonary TB among workers exposed to cattle infected with M. bovis, and increased risk among those occupationally exposed in non-ventilated spaces. Interspecies transmission is frequent and represents an occupational hazard in this setting.
authors: Laboratory of Clinical Microbiology, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Mexico City, Mexico.
authors: Pedro
authors: P
authors: Torres-Gonzalez
authors: Orbelin
authors: O
authors: Soberanis-Ramos
authors: Areli
authors: A
authors: Martinez-Gamboa
authors: Barbara
authors: B
authors: Chavez-Mazari
authors: Ma Teresa
authors: MT
authors: Barrios-Herrera
authors: Martha
authors: M
authors: Torres-Rojas
authors: Luis Pablo
authors: LP
authors: Cruz-Hervert
authors: Lourdes
authors: L
authors: Garcia-Garcia
authors: Mahavir
authors: M
authors: Singh
authors: Adrian
authors: A
authors: Gonzalez-Aguirre
authors: Alfredo
authors: A
authors: Ponce de Leon-Garduño
authors: José
authors: J
authors: Sifuentes-Osornio
authors: Miriam
authors: M
authors: Bobadilla-Del-Valle
mesh_terms: D000328:Adult; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology / Q000635:transmission; D018562:Disease Transmission, Infectious / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis; D008297:Male; D009163:Mycobacterium bovis / Q000472:pathogenicity*; D016273:Occupational Exposure; D014374:Tuberculin Test; D014376:Tuberculosis / Q000453:epidemiology* / Q000382:microbiology
references: Salud Publica Mex. 2000 Jan-Feb;42(1):48-52
references: 10743399
references: Curr Opin Pulm Med. 2009 May;15(3):188-200
references: 19387262
references: Clin Infect Dis. 2008 Jul 15;47(2):168-75
references: 18532886
references: J Clin Microbiol. 1997 Apr;35(4):907-14
references: 9157152
references: Conn Med. 2008 Aug;72(7):405-9
references: 18763668
references: Clin Infect Dis. 1994 Oct;19(4):784-6
references: 7803652
references: Clin Microbiol Infect. 2011 Jun;17(6):806-14
references: 21682801
references: Can J Public Health. 1994 Sep-Oct;85(5):326-9
references: 7804937
references: Tuber Lung Dis. 1996 Apr;77(2):103-8
references: 8762842
references: Bull World Health Organ. 1994;72(6):851-7
references: 7867130
references: Aust N Z J Med. 1988 Aug;18(5):701-3
references: 3072951
references: Salud Publica Mex. 1989 Jan-Feb;31(1):73-81
references: 2711258
references: Can Dis Wkly Rep. 1991 Nov 2;17(44):239-40, 243
references: 1841004
references: Infect Control Hosp Epidemiol. 2001 Feb;22(2):88-93
references: 11232884
references: Int J Tuberc Lung Dis. 1999 Aug;3(8):715-21
references: 10460105
references: Acta Paediatr. 1992 Sep;81(9):678-81
references: 1421907
references: Lancet Infect Dis. 2004 Dec;4(12):761-76
references: 15567126
references: Nature. 2008 Oct 23;455(7216):1029
references: 18948927
references: Vet Microbiol. 2010 Jan 27;140(3-4):371-81
references: 19773134
references: Int J Tuberc Lung Dis. 2003 Feb;7(2):180-5
references: 12588020
references: MMWR Recomm Rep. 2010 Jun 25;59(RR-5):1-25
references: 20577159
references: MMWR Morb Mortal Wkly Rep. 2005 Jun 24;54(24):605-8
references: 15973241
references: Int J Epidemiol. 2006 Dec;35(6):1447-54
references: 17008360
references: Emerg Infect Dis. 1998 Jan-Mar;4(1):59-70
references: 9452399
references: Salud Publica Mex. 1998 Jan-Feb;40(1):47-52
references: 9580502
references: Int J Tuberc Lung Dis. 2005 Jul;9(7):809-13
references: 16013779
references: Emerg Infect Dis. 2008 Jun;14(6):909-16
references: 18507901
references: Pediatrics. 2001 Aug;108(2):305-10
references: 11483792