The Union government had on May 20 urged states to declare the black fungus infection, observed in increasing numbers in COVID-19 survivors, a notifiable disease under the Epidemic Diseases Act. Three states and one Union Territory declared mucormycosis an epidemic on Thursday – Tamil Nadu, Odisha, Gujarat and Chandigarh – joining Telangana and Rajasthan which had done so a few days ago. What causes the infection and what circumstances make a person susceptible to contracting mucormycosis? And what are the symptoms to look out for? We answer some FAQs about the black fungus.

What is black fungus infection and what causes it? Mucormycosis is caused by mucormyete molds, organisms that are present in the air, leaves, piles of compost, soil and rotting wood. If exposed, the infection occurs when the fungus infects your central nervous system, eyes, sinuses, lungs, etc. However, it is important to note that not everyone who is exposed to the fungus will get infected.

What makes a person susceptible to infection? According to the Centres for Disease Control (CDC), mucormycosis is common among people who have lower immunity, or are immunocompromised or are taking medication that lowers the body’s ability to fight pathogens and sickness. People with diabetes (especially with diabetic ketoacidosis), cancer, who have had organ transplant or stem cell transplant, neutropenia (low number of white blood cells), long term corticosterioid use, iron overload in the body, skin injuries due to surgery, burns or wounds, prematurity and low birth weights are more vulnerable to getting infected by mucormycosis.

Is there a connection between COVID-19 and mucormycosis? Research is yet to establish a clear link between mucormycosis and COVID-19. However, most black fungus infections recorded in the first and second waves of the pandemic in India have been in people who recovered from COVID-19.

One of the factors appears to be high blood sugar levels in the survivors, which makes them vulnerable.  Dr Pamod Subhash, an oral and maxillofacial surgeon and office bearer of the Association of Oral and Maxillofacial Surgeons of India, had told TNM that people with no comorbidities who contracted mucormycosis had a high chance of having high blood sugar levels. Further, COVID-19 affects immunity in people which can make one susceptible to developing the infection, so does exposure to steroids, which increase blood sugar and weaken the immune system. However, some people who have neither been hospitalised nor taken steroids have also reported black fungus infections.

Doctors have also asked for distilled water to be used for humidification of patients with oxygen support, instead of tap water to reduce risk of germs.

What are the symptoms to watch out for? The signs of black fungus infection are one-sided facial swelling, headache, nasal or sinus congestion, fever, black discharge from the nose, dry black crusts in the nose, among others. If the spores enter the body through a cut or bruise in the skin, blackened skin tissue can also present as a symptom.

Doctors advise that another precaution that people can take is to watch out for their blood sugar. Apart from the CRP (C-Reactive Protein) to check for inflammation level in the body, a complete blood count or CBC test, a D-Dimer test to check for blood clots and ferritin test – which are part of a typical COVID-19 profile – patients can also do an RBS or random blood sugar test to know what their sugar levels are. If the levels are higher than normal, the person can get on medication as per doctor’s advice, said Dr Sonal, Professor and Head of the Department of Maxillofacial Surgery at the Government Dental College and Hospital, Ahmedabad.

How does mucormycosis spread? The infection, if not checked, can be quite aggressive. It enters and blocks blood vessels, cutting off blood supply to the tissue. Several cases of the black fungus have been found in the upper jaw, or maxilla, causing the entire jaw detaching from the skull. This happens because when blood supply to the bone (upper jaw) is cut off due to the fungus, the bone dies. The dead bone then detaches from the live bone – like a denture coming off.

If not treated in a timely manner, the fungus can spread quite quickly and can prove fatal. “The infection is so aggressive that it spreads faster than cancer. In 15 days, it can spread from your mouth to eyes and within a month to the brain,” Dr Sonal had told TNM.

It should be noted however, that the infection is NOT contagious, meaning, it does not spread from person to person.

How can the risk of mucormycosis be lowered? There is no vaccine against the black fungus infection, and it is difficult to avoid breathing in the fungal spores that cause the infection as these are commonly present in the environment. As per the CDC, these are the steps one can take to lower the risk.

- Avoid areas with a lot of dust like construction or excavation sites. If unavoidable, wear a well-fitted and fresh N95 mask.

- Avoid being at water-damaged buildings and flood water.

- Avoid activities that would require you to be in contact with soil or dust such as gardening, or being in wooded areas. If unavoidable, cover yourself well – wear shoes, long sleeved shirts, gloves. To prevent infection through skin, wash and clean skin injuries with soap and water, especially if exposed to soil or dust.