COVID-19 has lifted the lid on the risks of secondary pulmonary fungal infections in patients with severe respiratory viral illness – even previously immunocompetent individuals – and highlighted the importance of vigilant investigation to achieve early diagnoses, leading experts say.
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Illustration of a pulmonary aspergillosis, invasion of a lung tissue by mold fungi Aspergillus with close-up view of the fungi.
Most fungi are not under surveillance in the United States, leaving experts without a national picture of the true burden of infection through the pandemic. However, a collection of published case series, cohort studies, and reviews from Europe, the United States, and throughout the world – mainly pre-Omicron – show that fungal disease has affected a significant portion of critically ill patients with COVID-19, with concerning excess mortality, these experts say.
COVID-associated pulmonary aspergillosis (CAPA) has been the predominant fungal coinfection in the United States and internationally. But COVID-associated mucormycosis (CAM) – the infection that surged in India in early 2021 – has also affected some patients in the United States, published data show. So have Pneumocystitis pneumonia, cryptococcosis, histoplasmosis, and Candida infections (which mainly affect the bloodstream and abdomen), say the experts who were interviewed.
Dr. George Thompson
“We had predicted [a rise in] aspergillosis, but we saw more than we thought we’d see. Most fungal infections became more common with COVID-19,” said George Thompson, MD, professor of clinical medicine at the University of California, Davis, and cochair of the University of Alabama–based Mycoses Study Group Education Committee, a group of experts in medical mycology. Pneumocystitis, for instance, “has historically been associated with AIDS or different types of leukemia or lymphoma, and is not an infection we’ve typically seen in our otherwise healthy ICU patients,” he noted. “But we did see more of it [with COVID-19].”
More recently, with fewer patients during the Omicron phase in intensive care units with acute respiratory failure, the profile of fungal disease secondary to COVID-19 has changed. Increasing proportions of patients have traditional risk factors for aspergillosis, such as hematologic malignancies and longer-term, pre-COVID use of systemic corticosteroids – a change that makes the contribution of the viral illness harder to distinguish.
Moving forward, the lessons of the COVID era – the fungal risks to patients with serious viral infections and the persistence needed to diagnose aspergillosis and other pulmonary fungal infections using bronchoscopy and imperfect noninvasive tests – should be taken to heart, experts say.
“Fungal diseases are not rare. They’re just not diagnosed because no one thinks to look for them,” said Dr. Thompson, a contributor to a recently released World Health Organization report naming a “fungal priority pathogens” list.
“We’re going to continue to see [secondary fungal infections] with other respiratory viruses,” he said. And overall, given environmental and other changes, “we’re going to see more and more fungal disease in the patients we take care of.”