The WHO fungal priority pathogens list as a game-changer

Publication summary

In October 2022, the World Health Organization published the first list of global fungal priority pathogens, which followed the 2017 release of a priority list of bacterial pathogens. The list of priority fungi includes 19 groups of human pathogens prioritized by deaths, annual incidence, trends in incidence and prevalence, global distribution, need for inpatient care, risk of complications, antifungal resistance, preventability, and access to testing and evidence-based treatment. The process of forming the list involved identification of pathogens and prioritization criteria by a global expert group, pathogen ranking by more than 300 practitioners, and prioritization as critical, high, or moderate by more than 40 mycology experts. This review describes the knowns and unknowns surrounding the global burden of serious fungal disease and the potential of the WHO fungal priority pathogen list to guide research, resource allocation, and public health action.

Who this is for

• National health policymakers
• Medical mycologists
• Clinicians, especially intensivists or those who work with immunocompromised patients
• Fungal diagnostic and antifungal researchers, developers, and clinical trial managers

Key findings

Burden of serious fungal disease

Serious and invasive fungal diseases are difficult to diagnose and often mimic other infections. This difficulty, combined with the relative lack of global surveillance for fungal diseases in comparison to bacterial infections, contributes to uncertainty about the global burden of pathogenic fungi. Recent studies, however, suggest that the incidence of invasive infections is rising and that serious fungal disease is associated with more than 300 million infections globally and 1.5 million deaths per year. 

Possible contributors to increases in serious fungal disease include rises in immunocompromisation, the use of immunosuppressive agents that place people at risk for opportunistic fungal infection, hospitalization for COVID-19 and influenza, uncontrolled HIV infection, long-term respiratory conditions such as chronic obstructive pulmonary disease, the difficulty in diagnosing and treating many fungal infections, and high rates of treatment failure. The use of broad-spectrum fungicides in agriculture may also play a role in increasing the rate of human infections and antifungal resistance.

Strategies for reducing serious fungal disease

Because fungal disease awareness, research, and investment has lagged behind similar approaches to bacterial and viral pathogens, strategies to reduce the global burden of serious infections must encompass a wide range of activities while taking into consideration the unique difficulties associated with fungal diagnosis and therapy. Urgently needed strategies include surveillance at the national and global level, affordable and accessible point-of-care (or as close as possible) diagnostic tools, political and financial support for antifungal and diagnostic innovation, health-system changes to prioritize access to evidence-based tests and treatment that are inclusive of antifungal stewardship, and enhanced monitoring of antifungal susceptibility.

The potential of the WHO global fungal priority pathogen list

The intent of the prioritized fungal pathogen list is to provide some direction for investment in research, test and therapy development and access, and public health campaigns. Critically important fungal pathogens included Candida albicans, Aspergillus fumigatus, Candida auris, and Cryptococcus neoformans; the high-priority group included Histoplasma species and Mucorales. 

The list may improve or guide improved mycological laboratory capacity and training, better availability of data to demonstrate risk of infection and where resources might more effectiveness and equitably be used, wider availability of antifungals like liposomal amphotericin B that are less toxic than alternative amphotericin B formulations, access to rapid antigen assays especially for people living with HIV, and vaccine development. The authors also warn that the development of antifungals with new modes of action for human disease that are then also used in agriculture pose a serious threat for the emergence and increase of antifungal resistance.

Given the danger of invasive fungal diseases and the increases in risk factors that may predispose more people to infection, awareness and investment in reducing global fungal burden are crucial.