Emerging from the shadow of bacterial resistance, fungal infections are growing harder to treat
A ameaça silenciosa dos fungos patogénicos ganhou voz oficial: a Organização Mundial da Saúde identificou dezanove agentes fúngicos que colocam em risco crescente a saúde humana, impulsionados pelas alterações climáticas e pela resistência antimicrobiana. Estas infeções, historicamente eclipsadas pelas doenças bacterianas e virais, atingem com particular violência os mais vulneráveis — doentes oncológicos, tuberculosos, e os que sobreviveram às formas mais graves da COVID-19. Num momento em que o arsenal terapêutico disponível se resume a quatro categorias de antifúngicos e o desenvolvimento de novos fármacos avança a passo lento, a janela para agir está a estreitar-se.
- A OMS formalizou o alarme sobre infeções fúngicas ao identificar dezanove patogénios prioritários, alguns já resistentes à maioria dos tratamentos disponíveis e a expandir-se geograficamente.
- Durante a pandemia de COVID-19, hospitais registaram um aumento acentuado de infeções fúngicas em doentes críticos, expondo a fragilidade dos sistemas de saúde perante esta ameaça secundária.
- Apenas quatro classes de antifúngicos existem no mercado e o pipeline de novos medicamentos está praticamente vazio, deixando médicos sem alternativas quando os tratamentos convencionais falham.
- O uso excessivo de antifúngicos na agricultura acelera a resistência, enquanto as alterações climáticas alargam as zonas geográficas onde estes fungos prosperam — dois vetores que se reforçam mutuamente.
- A OMS apela a governos e investigadores para uma resposta coordenada e urgente, alertando que sem intervenção as mortes associadas a infeções fúngicas em contexto hospitalar irão aumentar.
A Organização Mundial da Saúde emitiu um alerta formal sobre as infeções fúngicas, identificando dezanove patogénios que representam uma ameaça crescente para a saúde pública. A lista foi dividida em três níveis de preocupação: no topo, em nível crítico, figuram a Candida auris — resistente à maioria dos medicamentos e responsável por surtos em hospitais de todo o mundo —, bem como Cryptococcus neoformans, Aspergillus fumigatus e Candida albicans. No nível seguinte surgem outras espécies de Candida e os Mucorales, o fungo por detrás da mucormicose, que se disseminou dramaticamente entre doentes graves na Índia durante a pandemia.
Estas infeções afetam sobretudo pessoas com o sistema imunitário comprometido — doentes com cancro, tuberculose ou doenças respiratórias severas. A pandemia de COVID-19 tornou o problema mais visível: os hospitais registaram um aumento significativo de infeções fúngicas em doentes críticos, revelando uma vulnerabilidade que o mundo não estava preparado para enfrentar. O problema agrava-se pelo facto de existirem apenas quatro categorias de antifúngicos disponíveis e de a investigação de novos tratamentos ser escassa.
A convergência de vários fatores torna a situação particularmente preocupante. As alterações climáticas estão a ampliar as zonas geográficas onde estes fungos conseguem sobreviver e proliferar. O uso excessivo de antifúngicos na agricultura está a gerar resistência. E os sistemas de vigilância são frágeis, com muitos casos a ficarem por registar. Hanan Balkhy, diretora-geral adjunta da OMS para a resistência antimicrobiana, descreveu estas infeções como uma crise que emergiu da sombra — construída em silêncio enquanto a atenção global estava voltada para outras ameaças.
A OMS pede uma resposta coordenada e urgente: desenvolver novos fármacos, reforçar a vigilância epidemiológica e reduzir o uso agrícola de antifúngicos. Sem essa mobilização, as infeções fúngicas tornar-se-ão uma causa cada vez mais frequente de morte hospitalar, especialmente nas regiões onde as alterações climáticas aceleram a disseminação dos fungos e onde o acesso aos tratamentos existentes é limitado.
The World Health Organization has sounded an alarm about a threat that has been quietly building in hospital wards and vulnerable populations worldwide: fungal infections that are becoming harder to treat and spreading to new places. In a formal alert, the WHO identified nineteen fungal pathogens that pose significant danger to human health, warning that climate change and antimicrobial resistance are expanding both how often these infections occur and where they can take hold.
Fungal infections have long been overshadowed by the more visible threats of bacterial and viral disease. But they strike with particular force against people whose bodies are already compromised—those battling cancer, tuberculosis, or severe respiratory illness. During the COVID-19 pandemic, hospitals saw a sharp rise in fungal infections among critically ill patients, a pattern that revealed how vulnerable the severely sick become to these pathogens. The problem is compounded by a stark reality: there are only four categories of antifungal drugs available, and the pipeline for new treatments is nearly empty. Researchers and pharmaceutical companies have not prioritized fungal disease the way they have other infections, leaving doctors with limited options when standard treatments fail.
The WHO's list divides the nineteen pathogens into three tiers of concern. At the critical level sits Candida auris, a fungus that resists most medications and has triggered outbreaks across hospital systems globally. Also in this highest category are Cryptococcus neoformans, Aspergillus fumigatus, and Candida albicans—all capable of causing severe, sometimes fatal infections. The high-priority tier includes other Candida species and Mucorales, the fungus responsible for mucormycosis, or black fungus, which surged dramatically among severely ill patients in India during the pandemic. Medium-priority pathogens round out the list, including Coccidioides and Cryptococcus gattii.
What makes this crisis particularly urgent is the convergence of multiple forces. Climate change is expanding the geographic range where these fungi can survive and spread. Overuse of antifungal drugs in agriculture is driving resistance, making infections harder to cure. And the knowledge gaps are enormous. The WHO acknowledges that estimating the true scale of fungal infections is difficult because surveillance systems are weak, diagnostic tools are inadequate, and many cases go unrecorded. Hanan Balkhy, the WHO's assistant director-general for antimicrobial resistance, described fungal infections as emerging from the shadow of bacterial resistance—a crisis that has been building while the world's attention was elsewhere.
The organization is calling for governments and researchers to mount a coordinated response to these nineteen pathogens. Without urgent action, fungal infections will likely become an increasingly common cause of death among hospitalized patients, particularly in regions where climate change accelerates fungal spread and where access to the few available treatments remains limited. The window to act—to develop new drugs, strengthen surveillance, and curb agricultural overuse of antifungals—is narrowing.
Notable Quotes
Emerging from the shadow of bacterial antimicrobial resistance, fungal infections are growing and becoming increasingly resistant to treatments, making them a public health concern worldwide— Hanan Balkhy, WHO assistant director-general for antimicrobial resistance
The Hearth Conversation Another angle on the story
Why has the WHO suddenly focused on fungal infections now, when they've existed for decades?
They haven't suddenly appeared—they've been growing quietly. But the pandemic exposed how vulnerable hospitalized patients are to them, and climate change is now expanding where these fungi can survive. The WHO is essentially saying: we've ignored this long enough.
You mentioned only four types of antifungal drugs exist. Why so few compared to antibiotics?
Fungi are more similar to human cells than bacteria are, which makes them harder to target without harming the patient. Drug companies also haven't invested heavily because fungal infections were seen as rare or affecting only the very sick. That calculation is changing, but the pipeline is still nearly empty.
The list mentions Candida auris specifically. What makes it different from other fungal infections?
It's highly resistant to most drugs and spreads easily in hospital settings. It's caused outbreaks across multiple countries. It's the kind of pathogen that can turn a hospital into a dangerous place if it takes hold.
You said agricultural overuse of antifungals is driving resistance. How does that work?
Farmers use antifungal chemicals to protect crops. That constant exposure creates pressure for fungi to evolve resistance, just like overuse of antibiotics in livestock does with bacteria. The fungi don't stay on the farm—they spread.
What happens to a patient if they get a drug-resistant fungal infection and the standard treatments don't work?
Their options narrow dramatically. They might try different drug combinations, but if the fungus is resistant to all four categories available, doctors are essentially managing symptoms and hoping the patient's immune system can fight it. Many don't survive.
Is this something ordinary people need to worry about, or mainly hospitalized patients?
Mainly people who are already very sick or immunocompromised. But that's the point—as climate change spreads these fungi geographically and resistance grows, the population at risk expands. It's not an immediate threat to healthy people, but it's a growing threat to anyone who ends up in a hospital.