‘Black fungus’ and Covid-19: Myths and facts

17

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.

Stay informed with live updates on the current Covid-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.

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.

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.”