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Background "Trace" results on Xpert MTB/RIF Ultra ("Ultra"; Cepheid) —a molecular diagnostic test for tuberculosis (TB)—are often interpreted as an indication for TB treatment, but may also represent detection of nonviable bacilli or analytical error. In community-screening settings where individual TB risk is low, there is limited guidance on how to interpret Ultra-trace results. Methods We conducted systematic Ultra TB screening of adults and adolescents (≥15 years) in Kampala, Uganda, through door-to-door and event-based sputum collection. We enrolled individuals with trace-positive sputum for detailed clinical, radiographic, and microbiological (including 2 sputum cultures, repeat Ultra, and for people with HIV, urine lipoarabinomannan) evaluation, and compared those findings with similar evaluations in controls with Ultra-negative and Ultra-positive (non-trace) sputum. Results Of 21 957 people screened with Ultra, 211 (1.0%) tested positive, including 96 (46% of positives) with trace results. Of 92 people enrolled with trace-positive sputum; 12% (11/92) were HIV-positive and 14% (13/92) had prior TB. The prevalence of TB among participants with trace-positive sputum results was 14% (13/92) by culture, 24% (22/92) using broader microbiological criteria, and 26% (24/92) after accounting for clinical diagnosis. The prevalence of cough and of abnormal chest computed tomography (CT) findings were 32% and 26%, respectively, if Ultra-negative; 34% and 54% if trace-positive/non–microbiologically confirmed; 72% and 95% if trace-positive/microbiologically confirmed; and 71% and 93% if Ultra-positive (more than trace). Conclusions Most individuals with trace-positive sputum in Ugandan communities did not have microbiologically confirmed TB but had more symptoms and chest CT abnormalities than people with Ultra-negative sputum. [ABSTRACT FROM AUTHOR]

Past copper mining within Kilembe valley between 1956–1982 left behind mine tailings rich in potentially toxic elements (PTEs). This study was conducted to assess the concentrations of PTEs in soils and the potential uptake by forage. Tailings, soils and forage were collected and analyzed using ICP-MS. The study established that over 60% of grazed plots contained high concentrations of Cu, Co, Ni and As. Copper in 35%, Co in 48% and Ni in 58% of forage soil plots exceeded the thresholds for agricultural soils. Bio-accumulation of Zn and Cu, was observed. Zinc in 14% of guinea grass (Panicum maximum), 33% coach grass (Digitalia Scarulum) and in 20% of elephant grasses (Penisetum perpureun) exceeded thresholds of 100–150 mg kg−1. Copper (Cu) concentrations in 20% of Penisetum perpureun and 14% of Digitalia Scarulum exceeded grazing thresholds of 25 mg kg−1. Containment of tailing erosion should be explored to control erosion of tailings into grazing areas. This is the first study of this kind which has investigated forage uptake of trace elements from Kilembe contaminated soils and the possible risks for grazing animals. It is also the first study to profile the differences in bioaccumulation potentials of different species of forage. The study further identifies a forage species of guinea grass and couch grass as having bioremediation potentials for zinc contaminated soils. [ABSTRACT FROM AUTHOR]