PR000666 (Project)

Description:Within the GC6-74 cohorts, 4,462 HIV-negative healthy household contacts of 1,098 index TB cases were recruited from 2006 to 2012 at four African sites included in this study i.e. SUN (Stellenbosch University, South Africa), MRC (Medical Research Council Unit, The Gambia), AHRI (Armauer Hansen Research Institute, Ethiopia) and MAK (Makerere University, Uganda). The study had an exclusion period of 3 months, such that participants, who were diagnosed with active TB within 3 months of enrolment, were excluded from analysis to prevent inclusion of participants who had incipient or asymptomatic clinical TB disease at enrolment. Additional exclusion criteria were positive HIV rapid test, current or previous anti-retroviral treatment, history of TB, pregnancy, participation in drug and/or vaccine clinical trials and chronic disease diagnosis or immunosuppressive therapy within the past 6 months, and living in the study area for less than 3 months. A total of 97 individuals who developed active TB within the two year follow-up period were included in this study and matched at a ratio of 1:4 with participants who remained healthy during the 2-year follow-up period (controls); matching, by site, age class, sex, and wherever possible year of recruitment. Initial samples collected upon enrolment were termed baseline (BL) samples. Further samples were taken 6 and 18 months post-exposure, provided that the participant had remained TB free at the time of sample collection. Metabolic profiling was carried out for each study site, using either serum or plasma samples. For a small number of samples, an insufficient amount of plasma was available, so the sample was diluted using RPMI buffer.