Although humans typically fight off fungal spores easily, those with compromised immunity or in intensive care units don’t fare as well, experts say.

For example, patients suffering from severe COVID-19 who became infected with the fungus Aspergillus fumigatus had a mortality rate of more than 80 percent, according to a review article by an international group of researchers published in Nature Microbiology.

“The key issue with fungi is that they’re an extremely neglected public health problem with few treatment options,” writes Gustavo Henrique Goldman, a professor at the University of São Paulo in Brazil, and one of the lead authors. “We're currently seeing more deaths caused by fungal diseases than malaria and tuberculosis together, so it’s hardly surprising that fungal diseases have taken advantage of the fact that so many people have been hospitalized because of COVID-19.”

Bronchoscopy is the recommended procedure for making a diagnosis of aspergillosis, the disease caused by the Aspergillus fumigatus fungus. But such verification can be a problem in low-to-middle income countries where bronchoscopy can be expensive and hard to obtain.

Bronchoscopy is considered a risky procedure in those areas where personal protective equipment (PPE) may be hard to come by, since it is an aerosolizing procedure that exposes healthcare workers to SARS-CoV-2.

Aspergillosis can remain in the upper airways for many days and can be contained with antifungals. But once it invades blood vessels in the lungs, mortality exceeds 80 percent even with antifungal therapy, according to the study.

In part, the global rise in fungal infections has been caused by use of steroids and other drugs that reduce immune system activity. Although it was a necessary strategy during the pandemic and the benefits outweighed risks, researchers warn that excessive use of immunosuppressant drugs must be avoided.

Global warming also plays a role in the problem since many fungi are adapting to higher temperatures, making humans more vulnerable. Experts agree that novel antifungal medications are needed more than ever.

Currently, there are just four classes of antifungals, compared with dozens for antibacterials (antibiotics), the authors write.

Diagnostic bronchoscopy sampling should be done quickly, at the first sign of suspected fungal infection, to reduce illness and potentially save lives, according to a recent study published in Tuberk Toraks.

”The fungus that does not cause disease in the normal patient population may cause progressive clinical conditions in immunosuppressed patients,” those authors write.

 Flexible bronchoscopy is an important diagnostic tool for isolating fungal agents, they say.

“Increased awareness and more routine diagnostic strategies are needed for early diagnosis of these infections, which is vital for improving survival,” Goldman and others write in their review article in Nature Microbiology. “Given that these infections disproportionally affect low- and middle-income countries, it is also key to provide low- and middle-income countries with the necessary resources to diagnose and treat these infections effectively.”