In India, COVID-19 has led to a surge in cases of a potentially fatal fungal infection called mucormycosis, popularly known as “black fungus.” The infection is every bit as dangerous as the media have portrayed it, but several myths are circulating on social media about potential sources of the infection and its treatment.
The human body is not the usual habitat for fungi that belong to the order Mucorales, which includes species typically found in soil, dust, decomposing vegetation, and animal dung.
Our immune system is usually more than a match for the fungi, but an “unholy trinity” of diabetes, COVID-19, and steroid treatment can weaken a person’s immunity to such an extent that these microorganisms can gain a foothold.
Diabetes not only increases a person’s risk of severe COVID-19 but also provides conditions in which fungal infections can thrive. To make matters worse, both COVID-19 and the steroid dexamethasone, which intensive care doctors use to treat it, suppress immunity.
The ensuing infection, known as mucormycosis or zygomycosis, spreads rapidly from the nose and sinuses to the face, jaw, eyes, and brain.
On May 26, 2021, there were 11,717 confirmed cases of mucormycosis in India, which has more peopleTrusted Source living with diabetes than any other country in the world, except China.
Even before the pandemic, the prevalence of mucormycosis may have been 70 times higher in India than the overall figure for the rest of the world.
The fungus blocks blood flow, which killsTrusted Source infected tissue, and it is this dead, or necrotic, tissue that causes the characteristic black discoloration of people’s skin, rather than the fungus itself.
Nonetheless, the term “black fungus” seems to have stuck.
Prof. Malcolm Richardson, a professor of medical mycology at the University of Manchester in the United Kingdom, told Medical News Today that the name is “totally inappropriate.”
“The agents of mucormycosis — Rhizopus oryzae, for example — are hyaline (transparent),” he wrote in an email.
“From a mycological point of view, the term ‘black fungus’ (or ‘black yeasts’) is restricted to fungi called dematiaceous, which have melanin in their cell walls. Many people have tried to correct this on Twitter but to no avail.”
He said the media in India were now using the similarly misleading terms “white fungus” and “yellow fungus” to describe supposed variants of mucormycosis.
Without immediate treatment with antifungal medication and surgery to remove necrotic tissue, mucormycosis is often fatal.
Before the pandemic, the Centers for Disease Control and Prevention (CDC) reported an overall mortality rate of 54%Trusted Source.
A 2021 systematic review of all COVID-19-related cases published in the scientific literature found 101 cases: 82 of them in India and 19 from the rest of the world. Among these cases, 31% were fatal.
Dr. Awadhesh Kumar Singh and his co-authors report that around 60% of all the cases occurred during an active SARS-CoV-2 infection and that 40% occurred after recovery.
In total, 80% of the patients had diabetes, and 76% had been treated with corticosteroids.