Two cases of black fungus have been detected at Birdem Hospital in patients who have recovered from Covid-19, a worrying sign as neighbouring India reports widespread infections.

One of the patients, aged 45, was detected with black fungus, known among doctors as mucormycosis, on May 8 and the other, aged 60, was detected on May 23, officials of the hospital said.

Those with uncontrolled diabetes and compromised immune system are at high risk, they added.

"In our lab, we confirmed two patients with mucormycosis. We are treating them and trying to control their blood sugar," said Lovely Barai, associate professor at the department of microbiology at Birdem.

The two individuals are the first Covid-recovered patients detected at the facility with the rare fungal disease, she told The Daily Star yesterday.

"A black fungus infection can turn critical in someone who has a compromised immune system. They need to be treated carefully… We are treating them cautiously."

People treating a coronavirus patient sometimes use steroids out of panic, she said, adding that this compromises the immune system and puts the patient at risk of a black fungus infection.

According to the United States Centers for Disease Control and Prevention, "Mucormycetes, the group of fungi that cause mucormycosis, are more common in soil than in air, and in summer and fall than in winter or spring. Most people come in contact with microscopic fungal spores every day, So, it's probably impossible to completely avoid coming in contact with mucormycetes.

These fungi aren't harmful to most people. However, for people who have weakened immune systems, breathing in mucormycete spores can cause an infection in the lungs or sinuses which can spread to other parts of the body."

A 2005 study on 929 cases dating back to 1885 found an overall mortality rate of 54 percent, according to the CDC.

Health experts in Dhaka said there is no reason to panic as people of all ages are not at risk of the disease.

Covid-19 patients, those who are diabetic, take steroids, have cancer or transplanted organs, and other comorbidities are susceptible to an infection, they said.

Coronavirus affects people's immune system and the treatment drugs further suppress their immune response, they added.

Barai said doctors at many health facilities prescribe steroids for aged Covid-19 patients without properly weighing the pros and cons of their decision.

Health officials on Sunday said they would soon release a guideline on preventing and treating the infection.

"The National Technical Advisory Committee on Covid-19 has been preparing a set of recommendations while the Public Health Advisory Committee is also working to set a prevention protocol. A prevention and treatment protocol on black fungus infection will be out soon," Nazmul Islam, director (disease control) at the Directorate General of Health Services (DGHS), told reports.

Nazrul also said that no unusual black fungus infection was reported in Bangladesh.

Over 7,200 people in India have been reported with mucormycosis and 219 of them have lost their lives, Indian media reported, quoting health officials. The rise in black fungus infections, mostly in patients who had severe coronavirus infections, has been linked to overuse of steroids, the reports add.

Tamil Nadu, Odisha, Gujarat, Rajasthan and Telangana states of India have declared black fungus as an epidemic.

Contacted, Prof Tahmina Shirin, director of Institute of Epidemiology Disease Control and Research (IEDCR), said no laboratory under the institute have reported any case of black fungus infection.

She declined to comment about the guideline health officials spoke about on Sunday.

Black fungus is treated with antifungal medicines, often given intravenously, according to the CDC. The most common medicines include Amphotericin B, which is currently being used in Indian states to combat the outbreak.

Patients may need to be on anti-fungal medicine for up to six weeks before they recover. Their recovery depends on how early the disease is diagnosed and treated.

Surgery is often required to amputate a dead or infected tissue. "In some patients, this may result in loss of upper jaw or sometimes even the eye," said the Indian health ministry in a recent statement.