By Eva Briggs, MD
Recently, I read an article about the emergence of fungal disease as the next potential cause of a pandemic.
The article mentioned Candida auris, a type of yeast capable of invading the lungs of patients weakened by COVID-19 and killing many of those infected.
The article also mentioned Aspergillus fumigatus, another fungus that can invade COVID-19-damaged lungs and kill patients.
The very next day, National Public Radio aired a story about Mucormycosis, a fungus ravaging COVID-19 patients in India.
So, while we often think of viruses and bacteria as infectious disease scourges, we shouldn’t forget about fungi.
Fungi have cell walls rather than cell membranes like animal cells. They cannot manufacture their own food like plants. They have nuclei, unlike bacteria. They are ubiquitous, with more than six million different species. Many fungi are beneficial. They produce fermented foods such as bread, beer and cheese. Mycorrhizal fungi assist plant growth. Fungi produce commercial enzymes such as lipase used in laundry detergent. Many mushrooms are tasty delicacies. The antibiotic penicillin was discovered because it is produced by fungi. Fungi are everywhere. Each of us inhales more than 1,000 fungal spores every day.
For a long time, scientists thought that fungi were not important pathogens because mammals have a core temperature higher than that preferred by fungi. Sure, the cooler outer surfaces of our body were at risk for fungal infections such as athlete’s foot, ringworm and yeast infections. But invasive infections seemed rare.
Prior to the mid-20th century people with impaired immune systems didn’t live very long. Improved medical therapies enable people with immune systems damaged by illness, cancer treatment and age to survive. Medicines can suppress the immune system in patients with autoimmune disorders as well as in transplant recipients. Many more people now live with compromised immune systems, rendering them potentially vulnerable to fungal infections.
Here’s a little more information about the three fungal infections I mentioned at the start of this article.
Candida auris was first identified as a disease-causing organism in 2009. Because it’s frequently resistant to most antifungal drugs, it is hard to eradicate not only from patients but from their environment. Once it invades a facility, it may survive on almost every surface: floors, walls, ceilings hospital beds, telephones, etc.
Aspergillus is a mold found almost everywhere both indoors and outdoors. Typically, it infects people whose lungs are weakened by illness such as cystic fibrosis and other lung diseases including COVID-19. It can also attack people that have impaired immune systems. It may invade into the blood vessels and beyond.
Mucormycosis, the disease starting to run rampant in India (and some other places) attacks COVID-19 patients with diabetes. It’s also called black fungus. Steroids, powerful anti-inflammatory drugs sometimes used to treat COVID-19 patients, also increase vulnerability to mucormycosis. The mortality rate is 50%. The fungus infects the lungs, and also the nose and sinuses. From the sinuses it can spread to the brain and the eyes. To attempt to treat the disease, sometimes surgery is necessary to remove the patient’s eye(s).
Other well-known invasive fungal diseases include pneumocystis pneumonia (the infection that tipped scientists into the discovery of HIV), blastomycosis and coccidiomycosis (valley fever).
One approach to combating fungal disease is the development of a vaccine. So far there has not been a vaccine against any fungal disease. But early research for a Valley fever vaccine is promising. Because dogs always have their nose in the dirt and therefore frequently inhale “Coccidiodes” spores, scientists are developing a new vaccine formula that might reach the market for use in dogs as early as next year. Canine vaccines are overseen by the US Department of Agriculture. Any future human vaccines require clinical trials overseen by the U.S. Food and Drug Administration, a process that normally takes years.
Eva Briggs is a retired medical doctor who practiced in Central New York for several decades. She lives in Marcellus.