title: Elevated serum 25-hydroxy (OH) vitamin D levels are associated with risk of TB progression in Gambian adults.
abstract: Vitamin D is essential in the host defence against tuberculosis (TB) as an immune modulator. The aim of this study was to determine the level of 25-hydroxyvitamin D (25 (OH) D) from adult TB index cases before and after treatment and their exposed household contacts (HHC) in The Gambia.
  
  
  
  Serum from adult index TB cases and their TB-exposed household contacts (HHC) was analysed for 25(OH) D and Vitamin D binding protein (VDBP) concentrations. Tuberculin skin test (TST) status was used as a measure of Mycobacterium tuberculosis (Mtb) infectivity in the HHC. In addition, HHC who later progressed to active TB (incident cases) were assessed alongside non-progressors to determine the influence of 25 (OH) D levels on TB risk.
  
  
  
  Eighty-three TB cases, 46 TST+ and 52 TST- HHC were analysed. Generally levels of 25(OH) D were considered insufficient in all subjects. However, median levels of 25(OH) D and VDBP were significantly higher in TB cases compared to both TST+ and TST- HHC at recruitment and were significantly reduced after TB therapy (p < 0.0001 for all). In addition, levels of serum 25(OH) D at recruitment were significantly higher in TB progressors compared to non-progressors (median (IQR): 25.0(20.8-29.2) in progressors and 20.3 (16.3-24.6) ng/ml in non-progressors; p = 0.007).
  
  
  
  In The Gambia, an equatorial country, 25(OH) D levels are higher in serum of TB progressors and those with active disease compared to latently infected and uninfected subjects. These results contrast to findings in non-equatorial countries.
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia. Electronic address: oowolabi@mrc.gm.
authors.forename: Olumuyiwa
authors.initials: O
authors.lastname: Owolabi
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia.
authors.forename: Schadrac
authors.initials: S
authors.lastname: Agbla
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia; Department of Medical Laboratory Science, University of Health and Allied Sciences, PMB 31 Ho, Volta Region, Ghana.
authors.forename: Patrick
authors.initials: P
authors.lastname: Owiafe
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia.
authors.forename: Simon
authors.initials: S
authors.lastname: Donkor
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia.
authors.forename: Toyin
authors.initials: T
authors.lastname: Togun
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia.
authors.forename: Abdou K
authors.initials: AK
authors.lastname: Sillah
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia; World Health Organisation Regional Office, Brazzaville, Congo.
authors.forename: Martin O C
authors.initials: MO
authors.lastname: Ota
authors.affiliation: Vaccines & Immunity Theme, Medical Research Council Unit, Atlantic Road, Fajara, Gambia.
authors.forename: Jayne S
authors.initials: JS
authors.lastname: Sutherland
mesh_terms: D000328:Adult; D000367:Age Factors; D000995:Antitubercular Agents / Q000627:therapeutic use; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016358:Contact Tracing; D018450:Disease Progression; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D055985:Latent Tuberculosis / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014376:Tuberculosis / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology; D015854:Up-Regulation; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014809:Vitamin D-Binding Protein / Q000097:blood; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D015415:Biomarkers; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25(OH) D; Incident cases; Latent TB infection; Tuberculosis; Vitamin D binding protein