vulnerable to Aspergillus. Te threat, which also surfaced during the 2009 flu pandemic, is leading some researchers to urge more careful fungal surveillance of the sickest COVID-19 patients and treatment with antifungal drugs. Aspergillus species are ubiquitous fungi in the environment and in our homes, and it can be opportunistic. Given the chance, it can become a serious infectious agent in human lungs (usually when the patient is immunocompromised or in some other way unable to ward off infections). In 2009, doctors saw a spike in previously healthy people who succumbed to Aspergillus. Tey had all first become sick with a new, pandemic strain of the influenza virus H1N1; before that, AIDS patients were often victims. For reasons scientists still don’t completely understand, influenza infections appear to make the fungus more deadly in people with a seemingly normal immune system. Now, something similar may be happening with COVID-19. Just as H1N1 was a severe strain of influenza, the SARS-CoV-2 virus is an especially dangerous form of coronavirus. Data on Aspergillus infections in people with COVID-19 are still sparse, but case reports point to worrying trends. One study from Germany found that one-quarter of critically ill COVID-19 patients also had Aspergillus infections. Another study of COVID-19 patients on ventilators found probable Aspergillus in one-third of them. It should be pointed out that it’s not uncommon for COVID-19 patients to be infected with other harmful microbes. But Aspergillus may be the deadliest threat among them. So what is the connection between COVID and this
fungal infection? Doctors say there are a few reasons why having COVID-19 might be an especially strong risk factor for an Aspergillus infection. One is that while COVID-19 can send parts of the immune system into overdrive, it also depletes certain immune cells, leaving a patient less able to fight off other infections. Te extreme damage to cells lining the lung also impairs the organ’s ability to clear out respiratory pathogens like Aspergillus. Te way physicians treat COVID-19 could also heighten the risk of an Aspergillus infection. Te steroid dexamethasone, shown to improve survival rates among severely ill COVID-19 patients, calms an overactive immune response that can lead to dangerous inflammation and organ damage. But immunosuppressive steroids are a double-edged sword, leaving the door open to other infections. A recent observational study of four COVID-19 patients with likely Aspergillus infections noted that three of them had received higher steroid doses than was recommended—all of them died. If doctors could easily identify Aspergillus infections, available antifungal drugs could fight them. But because the fungus can cause nonspecific symptoms such as coughing and shortness of breath that are already common in COVID-19 patients, doctors don’t always look for it. Recently, in Te Lancet, an international group of physicians and medical mycologists laid out recommendations for diagnosing Aspergillus infections in COVID-19 patients, including doing lung-imaging scans and taking samples from the lungs at regular intervals for testing. Te hope is that the guidelines will help COVID-19 doctors know whether they’re battling one deadly pathogen, or two.
CHRISTOPHER HOBBS’S
medicinal
MUSHROOMS THE ESSENTIAL GUIDE
“Nothing less than a masterpiece.” — James Lake, MD
“A must-have book for anyone interested in mushrooms, yes, but also health, healing, and nature.”
— Rosemary Gladstar, best-selling author and herbalist
ON SALE NOW! $24.95 Paperback | 978-1-63586-167-9
Fall 2021 FUNGI Volume 14:4 13
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