Explainer: What is the deadly ‘black fungus’ seen in Covid patients in India?

A rare black fungus that invades the brain is being increasingly seen in vulnerable patients in India, including those with Covid-19, as the health system continues to struggle in the midst of the pandemic.

The health ministry on Sunday released an advisory on how to treat the infection. In the state of Gujarat, about 300 cases had been reported in four cities, including Ahmedabad, according to data from state-run hospitals.

The fungus, called mucormycosis, “is very serious, has a high mortality, and you need surgery and lots of drugs to get on top of it once it takes hold”, said Prof Peter Collignon, who sits on the World Health Organization’s expert committee on antibiotic resistance and infectious diseases.

What is mucormycosis?

The disease is caused by a group of moulds, called mucormycetes, that live throughout the environment including in soil and on plants. Mucormycosis is seen throughout the world, including in the US and Australia. It can be acquired in hospitals – most commonly by vulnerable transplant patients – when the moulds get on hospital linens, travel through ventilation systems, or are transmitted on adhesives.

“They’re a family of fungus that gets into your sinuses and deposit there, and they can get into the air spaces in your head,” Collignon said. “And when your immune system can’t keep them under control they invade the base of your brain where it becomes a real problem, and really very serious.”

“You can also get the fungal infections in places where there’s a lot of earth-moving building work going on, because it stirs up a lot of dust in the area.”

The fungal spores are usually inhaled, and while most people’s immune systems can fend them off, people with conditions like diabetes or leukaemia that weaken the immune system, or those who take medications such as steroids that lower the body’s ability to fight germs, are prone to the spores developing into an infection.

The condition is usually very rare, with about 500 cases a year estimated to occur in the US prior to the pandemic (the exact number is difficult to determine as there is no national surveillance for the infection).

Why is it appearing now in India?

Collignon said Covid-19 was creating conditions for the infection to take hold. People’s immune systems were being compromised by the virus, and mucormycosis was being seen in particular in patients who also have diabetes.

“We give a lot of high dose steroids now to people with Covid-19 if they end up in intensive care as the steroids help to treat inflammation, but the steroids unfortunately also suppress your immune system.

“So that’s why we don’t like giving steroids to patients longer than we absolutely have to. We’re trying to decrease your inflammation with the steroids but that actually means your ability to fight normal infections, like fungus, is also compromised.”

Health systems are under intense pressure in India, and crowded and cramped environments are giving it more chance to spread.

How is it diagnosed?

Symptoms include pain and redness around the eyes and nose, a fever, headache, coughing, vomit with blood in it, black and bloody nasal discharge, pain on one side of the face and in the sinuses, blackish discoloration over the nose, tooth pain, and painful and blurred vision.

Fluid and tissue samples may be taken to confirm a diagnosis.

How is it prevented and treated?

Mucormycosis is expensive and difficult to treat, Collignon said, and has a mortality rate upwards of 50%.

“We usually put people with suppressed immune systems in what we call positive pressure rooms when they are admitted to hospital to reduce the risk of acquiring infections like mucormycosis, because by increasing the pressure in the room, so that the air flows out into the corridor, there’s less likely to be fungus or other things circulating in the air that the patient can breathe it in,” he said.

“Of course, a positive pressure room is the last place you want to put a Covid patient as it can spread the virus, making [mucormycosis] harder to prevent.”

Patients with mucormycosis are given antifungal drugs that can be quite toxic.

“You invariably need surgery as well to clear out the source of the fungus, which is usually the sinus, and the back of your throat at the back of your nose,” Collignon said. “You’ve got to get in there and cut out all of the fungal material. That surgery can be in very delicate places like the base of your brain.”

The Indian Council of Medical Research and the Union Health Ministry have issued an advisory urging people to wear shoes, long trousers, long sleeve shirts and gloves while handling soil, moss or manure. People should also maintain personal hygiene, ensure if they have diabetes that it is well controlled, and medical professionals should discontinue immune-suppressing drugs such as steroids as soon as they are able, the ministry said.