The Methodology Behind the List – A Systematic Approach to an Elusive Threat. How does a global organization systematically categorize and rank a diverse and often elusive group of pathogens? The World Health Organization’s Fungal Priority Pathogens List (FPPL) is the result of a rigorous and transparent process designed to cut through the complexity and identify the most urgent threats. The WHO’s experts adopted a sophisticated tool known as Multicriteria Decision Analysis (MCDA) to create the list. This is not a simple ranking but a comprehensive evaluation that allows for a nuanced assessment of each pathogen’s public health impact.
Why an Elusive Threat
The MCDA framework was crucial because it enabled the expert panel to consider multiple factors simultaneously. This is rather than focusing on a single criterion like mortality. To create the list, a panel of international experts first identified and selected 19 fungal pathogens of concern. They then evaluated each of these pathogens against 10 specific, carefully chosen criteria.
These criteria provided the foundation for the ranking process and included:
- Mortality: The number of deaths caused by the pathogen each year.
- Annual Incidence: The number of new infections that occur annually.
- Antifungal Resistance: The extent to which the pathogen has developed resistance to existing treatments.
- Invasiveness: The ability of the fungus to cause systemic and life-threatening disease.
- Diagnostic Availability: The global accessibility and reliability of diagnostic tools.
- Treatment Options: The availability and effectiveness of current therapies.
- Prevention Options: The availability of vaccines or other prophylactic measures.
- R&D Pipeline: The number of new drugs and diagnostics currently in development for the pathogen.
- Geographic Distribution: Whether the pathogen is endemic to a specific region or is globally distributed.
- Population at Risk: The size of the population susceptible to infection by the pathogen.
Based on the scoring of these criteria, the pathogens were grouped into three distinct priority levels. The Critical Group includes pathogens that scored highest across the board, representing the most significant public health threats and the most urgent unmet needs. The High Group consists of pathogens that pose a significant threat but may be less widespread or have slightly better treatment options than the critical group. Finally, the Medium Group includes pathogens that are still a cause for concern and require ongoing monitoring, research, and public health attention, but are not currently at the same level of urgency as the higher-priority groups.
This methodical and data-driven approach is what gives the FPPL its authority. By moving beyond anecdotal evidence and systematically evaluating each pathogen, the WHO has provided a clear, evidence-based roadmap for policymakers, researchers, and public health professionals. It is a powerful tool designed to mobilize resources and focus efforts on the most pressing fungal threats, ensuring that the global response is strategic, efficient, and ultimately, more effective in saving lives.