Explained | What is mucormycosis, and what causes the infection in COVID-19 patients?

How prevalent is the disease? Can it be prevented?

Updated - December 04, 2021 10:30 pm IST

Published - May 16, 2021 02:25 am IST

A health worker carries a COVID-19 patient outside the casualty ward at Guru Teg Bahadur hospital in New Delhi on April 24, 2021.

A health worker carries a COVID-19 patient outside the casualty ward at Guru Teg Bahadur hospital in New Delhi on April 24, 2021.

The story so far: Hospitals across the country have started to report a number of cases of mucormycosis, an invasive fungal infection affecting patients who have recently recovered from COVID-19. In common parlance, it also goes by the name ‘black fungus’, a direct reference to the blackening that is characteristic of the disease.

What is mucormycosis?

Mucormycosis is an aggressive and invasive fungal infection caused by a group of molds called mucormycetes. It can affect various organs but is currently manifesting as an invasive rhino-orbito-cerebral disease, crawling through the sinus and working its way to the brain, affecting the ear, nose, throat, and mouth. While it is not contagious, it can cause a lot of damage internally and can be fatal if not detected early.


While mucormycosis is an old disease, what is perhaps new and concerning is the sudden increase in the invasive form of the sinus variant, which involves the orbit, and at times the brain, leading to blindness, stroke or death, according to Dr. Mohan Kameswaran, Chief Surgeon and Director at the Madras ENT Research Foundation, Chennai.

How prevalent is the disease?

The Centers for Disease Control and Prevention, U.S., calls it a serious but rare disease. Without population-based estimates, it is difficult to determine the exact incidence and prevalence of mucormycosis in the Indian population, but a computational model-based method by Arunaloke Chakrabarti et al., in a journal , estimated a prevalence of 0.14 cases per 1000 individuals in India.

While the infection is being reported from many States, Maharashtra Health Minister, Rajesh Tope, told mediapersons recently that there could be over 2,000 such cases in the State as of now, and predicted that the figure may go up as the number of COVID-19 cases escalates. Dr. Ram Gopalakrishnan, senior consultant, Infectious Diseases, Apollo Hospitals, added that while no studies exist on the current prevalence, the infection remained a possibility for one in 10,000 persons who recovered from COVID-19.

Also read | ‘Mucormycosis is still a rare occurrence’

What causes the disease?

Diabetes mellitus is the most common underlying cause, followed by haematological malignancies and solid-organ transplants, according to a comparative study of several papers on the incidence of mucormycosis in India, published in a recent issue of Microorganisms. Diabetes mellitus was reported in 54% to 76% of cases, according to a report.

What seems to be triggering mucormycosis in patients post COVID-19 is, Dr. Kameswaran said, “an indiscriminate use of a high dose of steroids in COVID-19 patients, sometimes even in minimally symptomatic patients”. This leads to spikes in the sugar level among diabetics, which, in turn, renders them vulnerable. Dr. V. Mohan, senior diabetologist, Dr. Mohan’s Diabetes Specialities Centre, said steroids in some COVID-19 patients might be a life-saver, and therefore, they become a double-edged sword. Rational use of steroids is necessary, and constant monitoring of sugar levels and resorting to insulin use to control these levels if required, is essential, he added.

Also read | ‘Diabetics must immediately approach doctor if they have symptoms of mucormycosis’

Dr. Kameswaran said the use of monoclonal agents like Tocilizumab may be a factor, too. He added that while the fungi are present in the environment, the use of nasal prongs and other devices for oxygen delivery and possible breach of sterile conditions can possibly lead to cross-infection and hospital-acquired infection. “The question of COVID- 19 infection itself predisposing to invasive fungal disease would need further studies but cannot be ruled out at this stage,” he added.


Does the disease cause any distinct symptoms?

Dr. Nisar Sonam Poonam, associate consultant at the Department of Orbit and Occuloplasty at Sankara Nethralaya, Chennai, said the signs to watch out for are a stuffy nose, bloody, blackish, or brown discharge from the nose, blackish discolouration of the skin, swelling or numbness around the cheek, one-sided facial pain, toothache or jaw pain, drooping of the eyelids or eyelid swelling, double vision, redness of eyes, and sudden decrease in vision. The main line of treatment is an anti-fungal drug called amphotericin B, which is given over an extended period of time under the strict observation of a physician. Surgery to remove the fungus growth might also be warranted.

Also read | Telangana releases guidelines for control of mucormycosis

How can mucormycosis be prevented?

Following appropriate treatment protocols as recommended by the World Health Organization for COVID-19, including rational use of steroids and monoclonal antibodies only when they can help a patient, is important, said Dr. Kameswaran.

It is important to keep blood sugar levels under control and ensure that appropriate calibration of oral drugs or insulin is done from time to time, stressed

Dr. Mohan. Further, recognising the symptoms and seeking treatment early if there are two or three symptoms at a time is key. Like most illnesses, if detected early, mucormycosis can be cured.

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