Editorial: Enhancing global access to diagnostic tools for emerging tropical diseases in settings with limited resources

Larson Boundenga¹Falgunee K Parekh²Ricky Soong³Illich Manfred Mombo^1*

• ¹Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, Gabon
• ²Epipointe, Cary, United States
• ³National Institute of Allergy and Infectious Diseases, Bethesda, United States

Effective diagnostics at the human-vector interface are essential for detecting and interrupting the transmission cycles of vector-borne diseases. This may require the detection of pathogens in atypical biological matrices, which frequently presents a diagnostic challenge. A notable example is demonstrated with the Zika virus outbreak in Brazil, where Ferraz et al analysed semen samples from sperm banks. Their research revealed that, although serological screening is common, it does not reliably predict viral shedding in semen. This finding further highlights the significant risk of relying exclusively on antibody tests in reproductive health settings, and emphasises the potential benefit of other approaches to diagnostics such as the use of molecular assays (i.e., Nucleic Acid Amplification Tests) for managing the Zika outbreak. That is, it is critical to employ the appropriate diagnostic matched to the corresponding clinical matrix to effect positive public health objectives.Beyond human diagnostics, surveillance at the vector level presents its own complexities. In a comprehensive review of mosquito-borne diseases in East African urban areas, Joseph et al documented the widespread co-occurrence of Aedes, Culex, and Anopheles species. A key insight from their work is that the lack of standardised definitions for 'urban' environments hinders the comparability of entomological data.They consequently advocate harmonised surveillance protocols and the application of molecular xenomonitoring detecting pathogen DNA or RNA in vectors to accurately assess and monitor vectorial capacity across diverse ecological settings. Diagnostics are critically important during acute epidemics, where the speed and accuracy of the public health response are paramount. An after-action review of the 2023 dengue epidemic in Burkina Faso by Diao et al illustrates this complex reality.While the country demonstrated improved preparedness compared to previous outbreaks, the review identified persistent, critical gaps in leadership, strategic planning, and laboratory logistics. This analysis underscores a fundamental lesson: sustainable access to diagnostics is inextricably linked to robust governance, effective coordination, and resilient supply chains.The challenge of diagnostic reliability extends beyond systemic issues with the public health enterprise, and can include the biological characteristics of pathogens themselves. Chukwudi et al documented this phenomenon in their study on rapid diagnostic tests (RDTs) for human African trypanosomiasis (HAT) in Nigeria. They found that despite the practical advantages of RDTs, their sensitivity was compromised by the local antigenic diversity of Trypanosoma brucei strains, leading to several falsenegative results in confirmed cases. Their study highlights a broader implication, diagnostic tools developed for a pathogen could depend on the geographical or epidemiological context. One cannot assume an assay will be universally effective in detecting a given pathogen, especially if it was not specifically designed for inclusivity of known divergence of strains. Further, it emphasizes the importance of rigorous validation against local circulating strains to ensure clinical utility. Building resilient diagnostic access requires structural investments that extend beyond disease-specific innovations to strengthen entire laboratory systems. A compelling case study by Kohar et al examines Liberia's systematic efforts to rebuild its national diagnostic network following decades of conflict and the devastating Ebola outbreak.Their research documents how strategic reforms in governance, specialized workforce training, and the implementation of robust quality management systems led to measurable improvements in diagnostic capacity. Crucially, however, the authors emphasize that sustaining these hard-won gains is contingent upon three interdependent factors-continuous financial investment, full integration of laboratory data into national surveillance systems, and unwavering long-term political commitment. This analysis underscores that systemic diagnostic resilience is not a onetime achievement but a continuous process dependent on foundational health system support. Taken together, the contributions to this Research Topic highlight four interdependent lessons (Figure 1): interest prior to deployment. These points are reinforced by broader literature. For example, frameworks for the rapid development of diagnostics during outbreaks emphasise iterative validation and integration with surveillance networks (5). Reviews of point-of-care diagnostics in settings with limited resources highlight both opportunities and persistent implementation challenges (6). While experiences with mobile health and AI-assisted diagnostic tools show promise, they also emphasise the need for local adaptation and user-centred design (7). This Research Topic collectively demonstrates that improving diagnostic access for emerging tropical diseases demands a multifaceted approach that extends far beyond technological innovation alone. Achieving accessible diagnostics necessitates their seamless integration into broader health systems, rigorous validation across diverse ecological and epidemiological contexts, and the strengthening of laboratory governance and supply chains. Consequently, diagnostic accessibility is not just a technical hurdle that must be overcome but also an urgent public health need.Ultimately, closing the diagnostic gap and fortifying global health security will depend on sustained, integrated collaboration that unites assay developers, scientists, laboratory professionals, clinicians, and public health policymakers.