Article Text
Abstract
Background Mycobacterium tuberculosis (Mtb) transmission among households contributes significantly to the tuberculosis (TB) burden. Understanding TB risks and the prevalence of Mtb infection in affected households may help designing strategies for case-finding and targeted prevention. The EDCTP-funded ERASE-TB study aims to validate new diagnostic tests in a cohort of household contacts (HHCs) of adults with infectious pulmonary TB.
Methods 2,101 HHCs ≥10 years of age were enrolled across three sites in Mozambique, Tanzania and Zimbabwe and are being followed up for 24 months. Enrolled HHCs undergo 6-monthly symptom screening, physical examinations and chest X-ray (CXR). HHCs with symptoms presumptive of TB and/or a CXR suggestive of TB undergo sputum-based tests, i.e., Xpert MTB/Rif Ultra/culture. At each visit, novel diagnostics, e.g. TAM-TB and Xpert Host Response (Cepheid), are conducted and blood and urine samples stored in a biorepository. The biorepository will be used for future investigations of new diagnostics applying a case-control design. Testing for Mtb infection is done at baseline using interferon-gamma release assays (IGRA; SD Biosensor).
Results An average of 2.4 contacts per household were recruited. The median age was 26.7, 62% were females, 321 (15%) were living with HIV, and 44 (14%)of these were newly diagnosed. One-quarter of the enrolled HHCs were children aged 10–18 years. At baseline, 355 (17%) had TB-related symptoms and 5% CXRs suggestive of TB. The prevalence of pulmonary TB was 0.7% while the prevalence of Mtb infection was 54%. Follow-up of study participants is ongoing.
Conclusion Despite COVID-19 related interruptions, the targeted enrolment size of 2100 HHC was achieved. While a considerable proportion of HHC had Mtb infection at baseline or had symptoms and/or CXR findings suggestive of TB, less than 1% were diagnosed with TB. This is a relatively high HIV prevalence, albeit mostly known and on treatment.