Fungal Taxa Responsible for Mucormycosis/“Black Fungus” among COVID-19 Patients in India

Abstract

Mucormycosis is caused by fungi belonging to the order Mucorales. The term “Black Fungus” has been widely applied to human pathogenic Mucorales in India. They mainly infect the sinuses and brain, lungs, stomach and intestines, and skin. While this has been considered a rare disease, thousands of cases have been reported during the second wave of COVID-19 in India, between the months of April and June 2021. Hitherto, more than 45,374 cases and over 4300 deaths have been reported among COVID-19 patients across India from April 2021 to July 21, 2021. Though the mortality rate is estimated to be 50%, it could be above 90% if left untreated. In India, Rhizopus arrhizus has been related to be the most common species to cause human mucormycosis, followed by Apophysomyces variabilis, Rhizopus microsporus, and R. homothallicus. Accurate sample identification of human pathogenic Mucorales species is challenging especially due to the frequent lack of diagnostic morphological features. Traditionally, the culture-based approach has been extensively used to isolate and characterize human pathogenic Mucorales. However, this may not be an appropriate approach to objectively isolate and characterize all species, as the germination and growth of fungal spores are highly dependent on culture media and environmental conditions. Therefore, a robust approach to the accurate and rapid identification of human pathogenic Mucorales species is a prerequisite. The metagenomic approach comprehensively sequences and analyzes all genetic material in a complex biological sample and, consequently, this could be an appropriate approach to objectively characterize human pathogenic Mucorales taxa without the need for in vitro culture. The precise identification of the species will not only be useful for the correct diagnosis of this disease, but also for the development of antifungal drugs specific for each species. Accurate and rapid species identification is desperately needed to save lives in the mucormycosis outbreak among COVID-19 patients in India and neighboring countries.

Emerging cases of mucormycosis in post Covid-19 disease patients

“…8 The genera of Mucorales are one of the best decomposers of organic materials and are often found in decaying organic materials such as rooted fruits and vegetables, plant litter, and animal manure. 12 The Mucor sp., Rhizopus sp., Asidia and Cunningham ella are the main causative agent for MC in humans. 13 Spores of the mucorales are highly prevalent in the air.…”

Commentary: A Machine-Generated View of the Role of Blood Glucose Levels in the Severity of COVID-19. A Metabolic Endocrinology Perspective

“…The other COVID-associated pandemic is mucormycosis, a normally rare infection caused by a fairly ubiquitous filamentous mold fungus ( 50 ). However, large numbers of cases have been reported in patients with COVID-19 ( 51 ): as with COVID-19, males appear to be at greater risk ( 52 ). Predominantly the cases have been within India, which reported over 45,000 cases and 4,300 deaths between April and July of 2021 ( 51 ); but cases have also been reported globally ( 52 ).…”

“…However, large numbers of cases have been reported in patients with COVID-19 ( 51 ): as with COVID-19, males appear to be at greater risk ( 52 ). Predominantly the cases have been within India, which reported over 45,000 cases and 4,300 deaths between April and July of 2021 ( 51 ); but cases have also been reported globally ( 52 ). The infections have mostly been rhino-orbital mucormycosis which has a mortality rate as high as 30-50% with limited treatment options frequently necessitating the removal of the eyes ( 52 , 53 ).…”

Resolving the equation between mucormycosis and COVID-19 disease

“…The mucormycosis related mortality is 35–50% in afflicted people [ 1 ]. In a year, almost 45,000 cases of mucormycosis are already reported [ 4 ]. Most of the cases have been reported from India, which coincidently has second highest number of diabetic people in the world [ 5 ].…”

“…Besides that, France, Iran, Russia, Pakistan, Bangladesh, Mexico, Oman, Egypt, Argentina, United States of America etc. have reported cases of this fungus as well [ 4 , 6 – 10 ].…”