WHO identifies potentially deadly fungal pathogens

The World Health Organization (WHO) today released its first-ever list of fungal ‘priority pathogens’, identifying 19 fungi that have emerged as significant threats to public health due to their ability to cause invasive infections. and their growing resistance to antifungal drugs.

Although data on the prevalence of invasive fungal infections and patterns of antifungal resistance are sparse and little is known about some of these pathogens, WHO officials say new evidence suggests that the incidence and geographic spread of fungal diseases are increasing due to climate change and increased global travel. The COVID-19 pandemic has also shed light on the problem, with the reported incidence of invasive fungal infections increasing in hospitalized COVID patients.

In addition, the population most at risk of invasive infections caused by these pathogens, including cancer patients, people living with HIV/AIDS, organ recipients and other immunocompromised patients, is increasing.

WHO officials are concerned that the limited number of antifungal drugs, the lack of rapid and sensitive diagnostics and the limited financial resources devoted to fungal infections are hampering the ability to detect and respond to the growing problem. They hope the list of priority fungal pathogens could have a similar impact to the document it was modeled on – the 2017 WHO list of priority bacterial pathogens.

“We want this report to catalyze research and development on new antifungals and new diagnostics for fungal diseases,” said Haileyesus Getahun, MD, MPH, PhD, Global AMR Coordinating Director at WHO, during a press briefing.

He added that identifying these 19 fungal pathogens among thousands of fungi will help direct research efforts and direct much-needed public and private investment in treatments and diagnostics.

Currently, fungal infections receive less than 1.5% of all infectious disease research funding.

Focus on invasive fungal infections

Like the 2017 Priority Bacterial Pathogens report, the document is divided into three categories based on public health impact and/or emerging risk of antifungal resistance: critical, high, and medium priority, with a rating indicating that some of the pathogens might be of greater concern. in areas where they are endemic. For each category, antifungal resistance was the most important endpoint, followed by annual incidence, morbidity and mortality.

Among the mushrooms of the critical priority group is candida auris, the multi-resistant yeast that was first discovered in Japan in 2009 and has since spread around the world. Invasive infections caused by cowries, which spreads easily in healthcare settings and in some cases is resistant to all classes of antifungal drugs, is fatal in 53% of patients.

Another one candidiasis the species to which the critical priority is candida albicans, which is common in the mouth, throat, intestines, vagina, and skin, but can cause serious illness when it invades other tissues.

Also in the critical priority group is Cryptococcus neoformans, a pathogenic yeast that lives in the environment and can cause serious infections after being inhaled, and Aspergillus fumigatusan environmental mold that can cause serious lung infections and poses a particular threat to patients with cystic fibrosis, influenza and COVID-19.

Among the fungi listed as high priority, three others candidiasis species (Candida glabrata, Candida tropicalis, and Candida parapsilosis), Histoplasm spp., and Mucorales (a large group of fungi consisting of different genera). The medium priority group includes Scedosporium sp., candida krusei, and Coccidioides spp., which causes valley fever.

The greatest concern with these pathogens is when they enter the bloodstream, especially in critically ill and immunocompromised patients. Carmem Pessoa-Silva, MD, AMR team leader at WHO, highlighted the presence of candidiasis species in all three groups, noting the ability of the fungus to cause fatal blood infections.

“Mortality attributable to candidiasis blood infections are very high,” she said. “The figures vary between studies, but they are almost always above 30%.

Due to the high estimated mortality and the need for more data, Pessoa-Silva said the WHO has started monitoring the incidence of candidiasis blood infections in 23 countries. She also said that WHO’s Global Antimicrobial Resistance and Use (GLASS) Surveillance System will soon collect resistance data on isolates from candidiasis blood infections, which have become increasingly resistant to the four classes of antifungal drugs (azoles, echinocandins, polyenes and pyrimidines) currently used in clinical practice.

“For most critical and high-priority pathogens, treatment options are limited and highly toxic,” she said.

Pessoa-Silva said that in addition to increased surveillance and the development of antifungals, greater laboratory capacity and better diagnostic tools are also desperately needed. She noted that because invasive fungal infections often have similar symptoms to bacterial infections, patients are often misdiagnosed and treated with antibiotics instead of antifungals.

A One Health problem

WHO officials have also highlighted that the emergence of resistant fungal pathogens as a global public health threat is a unique health concern, driven in part by the inappropriate use of antifungals in the ‘agriculture. For example, the report notes that the widespread use of azoles as fungicides to protect plants against fungal infections has contributed to increased rates of azole-resistant bacteria. A fumigatus infections in humans. Azoles are the first-line treatment for invasive aspergillosis.

Gethun said that the quadripartite organizations (WHO, United Nations [UN] the Food and Agriculture Organization of the United Nations, the World Organization for Animal Health and the United Nations Environment Programme) have begun to take steps to identify the antifungals essential to human health and to develop strategies to ensure that they are not used inappropriately in agriculture.

WHO officials have said that while there are significant knowledge gaps about the global burden of invasive fungal pathogens, it is important to “ring the bell” now and start boosting targeted research investment. and public health interventions. Hatim Sati, PhD, MPH, technical lead for WHO’s AMR division, said if one thing has been learned from the COVID-19 pandemic, it’s if you can do something early on to inform the public health response, it should be done.

“We don’t need to wait for things to be catastrophic to act,” he said.