Tropical Medicine and Infectious Disease

Melioidosis is increasingly recognised in tropical and subtropical regions worldwide as a serious and potentially fatal bacterial infection affecting humans and animals, acquired from the environment. Until now, human cases of melioidosis had not been reported in Southern Africa. Over a four-year period, we identified three human and two animal cases of melioidosis in South Africa and Namibia. Burkholderia pseudomallei isolates were investigated by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and whole-genome sequencing (WGS). Phylogenetic analysis demonstrated substantial diversity, suggesting long-term cryptic persistence of the bacterium in the Southern African region. Limited awareness of the disease and inadequate diagnostic capacity likely contribute to its apparent rarity in the region. These findings underscore the urgent need for increased surveillance, improved diagnostics, and greater awareness of melioidosis in Southern Africa to better understand its true epidemiological burden and prevent future cases.

Clinical trajectories following Trypanosoma cruzi infection are heterogeneous, and the determinants of post-treatment parasitological dynamics and cardiac progression remain incompletely characterized, particularly in TcI-predominant regions. This study assessed, in both the acute phase and the indeterminate chronic form, the association between TcI infection and molecular clearance kinetics, cardiac progression, and the prognostic value of early molecular response. An ambispective cohort in Colombia included patients with acute or indeterminate chronic infection followed between 2000 and 2023. Sustained clearance was defined as two consecutive negative quantitative polymerase chain reaction results obtained at separate visits. Time-to-event analyses were conducted using Kaplan–Meier curves and Cox proportional hazards models. TcI infection was consistently associated with delayed molecular clearance in both clinical presentations. Although long-term clearance was achieved in most patients, TcI infection was independently associated with a higher risk of cardiac progression. In contrast, quantitative polymerase chain reaction negativity at 12 months was associated with reduced subsequent progression risk, indicating that sustained molecular response is a clinically meaningful prognostic marker. Collectively, these findings support the incorporation of early molecular monitoring into risk-stratified follow-up strategies in TcI-predominant settings and reinforce the need for phase-specific clinical management approaches.

Background: Tuberculosis (TB) remains a major global health challenge, with transmission influenced by the incidence of contagious people with TB, the duration of infectivity, and the probability of contact with susceptible individuals. This review synthesizes recent evidence on established and emerging risk factors influencing TB transmission, particularly in light of global trends such as migration, urbanization, and demographic shifts, to guide future prevention and control strategies. This scoping review maps and synthesizes evidence from systematic reviews on risk factors for Mycobacterium tuberculosis exposure. Methods: A preliminary general literature search was conducted in PubMed on 25 August 2024, using the keywords “tuberculosis,” “risk factors,” and “systematic review.” A subsequent targeted search focused on systematic reviews published since 2000 that examined social and environmental determinants of exposure to M. tuberculosis identified in the general search. Original research and reviews spanning pre-2000 were excluded. Data extraction and synthesis followed PRISMA-ScR guidelines. Results: Of the 344 systematic reviews identified, 14 met the eligibility criteria, reporting on key risk factors contributing to the incidence of contagious people with TB, the duration of infectivity, and the probability of contact. These risk factors included homelessness, migration, occupational exposure, urbanization, climate change, and air pollution. The findings emphasize the complex interrelated role of social and environmental determinants in driving TB transmission. Conclusion: This review highlights the need for a multi-sectoral approach to TB, as climate change, air pollution, overcrowding, stigma, and limited healthcare access exacerbate established risks related to poverty. Effective prevention and control require targeted interventions that address these interconnected factors.