The Spectrum of Tuberculosis Disease in an Urban Ugandan Community and Its Health Facilities

Abstract

Background New, sensitive diagnostic tests facilitate identification and investigation of milder forms of tuberculosis (TB) disease. We used community-based TB testing with the Xpert MTB/RIF Ultra assay (“Ultra”) to characterize individuals with previously undiagnosed TB and compare them to those from the same community who were diagnosed with TB through routine care. Methods We offered community-based sputum Ultra testing to adult residents of a well-defined area (population 34 000 adults) in Kampala, Uganda, via door-to-door screening and venue-based testing, then used detailed interview and laboratory testing to characterize TB-positive individuals. We compared these individuals to residents diagnosed with pulmonary TB at local health facilities and a representative sample of residents without TB (controls). Results Of 12 032 residents with interpretable Ultra results, 113 (940 [95% confidence interval {CI}, 780–1130] per 100 000) tested positive, including 71 (63%) positive at the lowest (trace) level. A spectrum of TB disease was observed in terms of chronic cough (93% among health facility–diagnosed cases, 77% among residents with positive community-based Ultra results at levels above trace, 33% among trace-positive community participants, and 18% among TB-negative controls), TB symptom prevalence (99%, 87%, 60%, and 38%, respectively), and C-reactive protein (75th percentile: 101 mg/L, 28 mg/L, 6 mg/L, and 4 mg/L, respectively). Community-diagnosed cases were less likely than health facility–diagnosed cases to have human immunodeficiency virus coinfection or previous TB. The specificity of Ultra was 99.4% (95% CI, 99.2%–99.5%) relative to a single spot sputum culture. Conclusions People with undiagnosed prevalent TB in the community have different characteristics than those diagnosed with pulmonary TB in health facilities. Newer diagnostic tests may identify a group of people with early or very mild disease.

Prevalence ofMycobacterium tuberculosisin Sputum and Reported Symptoms Among Clinic Attendees Compared With a Community Survey in Rural South Africa

“…National TB prevalence survey estimates are based on 2 specimens and our estimate is therefore likely to underestimate prevalence compared with the national survey and other surveys in which multiple samples are collected. Our community estimates are consistent with those reported in a recent study from Uganda based on a single sputum specimen tested with Xpert Ultra [24]. Including all Xpert Ultra-positive tests resulted in an estimated community prevalence of 940 (95% CI, 780-1130) per 100 000 and 420 (95% CI, 320-550) per 100 000 adults when Xpert Ultra trace-positive and culture-negative sputum results were excluded.…”

“…In both surveys, most participants with culture-positive sputum did not report any symptoms, although reporting TB symptoms was associated with having culture-positive sputum. This has been reported in other community-based TB prevalence surveys [22][23][24] but not previously reported among adult clinic attendees. The degree of infectiousness of asymptomatic individuals with subclinical disease compared with symptomatic people is not known [25,26].…”

Computer-aided interpretation of chest radiography reveals the spectrum of tuberculosis in rural South Africa

“…This finding is in line with a recent study from a population-based screening in urban Uganda, which showed that individuals newly diagnosed with active TB in community-based screening have fewer symptoms, compared to people diagnosed at health facilities. 29 It is also in line with the recently completed South African National TB prevalence survey (57.7% asymptomatic) 30 and a recent meta-analysis of global TB prevalence surveys (79-97% asymptomatic) 31 . Asymptomatic TB eludes traditional symptom-based TB screening algorithms but is identifiable by CXR abnormality in most cases.…”

Characterization of geographic mobility among participants in facility- and community-based tuberculosis case finding in urban Uganda

“…This analysis was conducted as part of the STOMP-TB (Strategies for Treating, Observing, Managing, and Preventing Tuberculosis) study, an ongoing population-based study in a densely populated area consisting of 37 contiguous administrative zones in Kampala, Uganda (estimated population: 50,436, total area 2.2 km 2 [ 28 ]). The STOMP-TB study enrolls patients through two mechanisms: health facility TB diagnostic testing (from May 2018-July 2021) and active community outreach and testing (Phase 1 conducted from February to December 2019).…”