- Monica Slavin, Karin Thursky
- This article was first published in “The Conversation”
Fungal infections can be devastating. In particular, mucormycosis (mucormycosis) is aggravating the suffering of a country deeply mired in the new crown crisis. We have seen reports of mucormycosis in India, which is often called “black fungus” (black fungus), which is found in patients who have been infected with the new crown or are recovering from the new crown infection.
As of March this year, 41 cases of mucormycosis related to the new crown virus infection have been recorded around the world, 70% of which are in India. The report states that the number of cases is much higher now. Considering the current outbreak of the new crown epidemic in India, this is not surprising.
What is mucormycosis? How is it related to the new coronavirus?
What is mucormycosis?
Mucormycosis, formerly known as zygomycosis, is a disease caused by a fungus belonging to the order Mucorales. This fungus is usually found in the soil and other environments, and is often associated with decaying organic matter, such as fruits and vegetables.
Rhizopus oryzae is the most common cause of human infection among this fungus. But in India, another squamous fungus found in tropical and subtropical climates is also common.
In the laboratory, these fungi grow rapidly and have a fuzzy dark brown appearance.
Those fungi that cause human diseases grow well in human temperature and acidic environments-the same phenomenon occurs when tissues are dying, or when diabetes is out of control.
How does mucormycosis come from?
Fungi of the order Mucor are considered opportunistic, and they usually infect people with compromised immune systems or tissues. The use of glucocorticoids and other drugs that suppress the immune system may lead to impaired immune function, and may also lead to other immune-deficiency conditions, such as cancer or metastasis. Tissue damage may occur after trauma or surgery.
Humans can contract mucormycosis in three ways: inhaling spores, swallowing spores in food or medicine, or contaminating the wound with spores.
Inhalation is the most common. We actually inhale many fungal spores every day. But if our immune system and lungs are healthy, they usually prevent them from causing infections.
When our lungs are damaged and our immune system is suppressed, such as patients undergoing severe COVID-19 treatment, these spores will grow in the respiratory tract or sinuses and invade body tissues.
Mucormycosis may appear in the lungs, but the nose and sinuses are the most common sites of infection. From there, it spreads to the eyes and may cause blindness, or it spreads to the brain, causing headaches or epilepsy.
It can also affect the skin. After being injured in a natural disaster, or on a battlefield where the wound is contaminated by soil and water, life-threatening wound infections can occur.
surroundings
In countries outside of India, mucormycosis associated with the new crown is rare. Why is the situation so different there?
Before the new crown pandemic, mucormycosis was much more common in India than in other countries. In India, 14 people per 100,000 people suffer from the disease, while in Australia, only 0.06 people per 100,000 people suffer from the disease.
Globally, outbreaks of mucormycosis are caused by contaminated products such as hospital bed sheets, medicines and packaged food. However, according to many reports, the widespread spread of mucormycosis in India does not come from a single source of pollution.
Mucor is found in soil, decaying food, bird and animal excrement, water and air around construction sites, and humid environments.
Although it has never been compared, the environmental burden of mucor in Australia may be lower than in India.
But in India, there may be another factor at work-diabetes.
When diabetes is poorly controlled, blood sugar will be high and tissues will become relatively acidic-this is a good environment for the growth of mucor. Long before the COVID-19 pandemic, this was identified as a risk that caused mucormycosis in India (diabetes is increasingly prevalent in India and often uncontrolled) and worldwide. Between 2000 and 2017, 40% of all mucormycosis cases published in global scientific journals developed diabetes.
A recent summary of mucormycosis related to the new coronavirus showed that 94% of patients have diabetes and 67% of patients are poorly controlled.
A perfect storm
People with diabetes and obesity often have severe symptoms after being infected with the new coronavirus. This means that they are more likely to receive glucocorticoids, which are often used to treat new coronary disease. But glucocorticoids, together with diabetes, increase the risk of mucormycosis.
At the same time, the new coronavirus will damage airway tissues and blood vessels, which may also increase the possibility of fungal infections.
Therefore, the damage to tissues and blood vessels caused by the new crown infection, the use of glucocorticoid therapy, the high infection rate of the diabetic population, and the wider exposure of fungi in the environment may all be the reasons for the status of mucormycosis in India.
The challenge of treatment
In many Western countries, we have seen an increase in cases of infection with another fungus, Aspergillosis, among patients who are severely infected with the new coronavirus, require intensive care management, and receive glucocorticoid treatment. This fungus also exists in the environment, but belongs to a different family.
Aspergillus is the most common opportunistic fungus in the world, and we have a test method to quickly diagnose this infection. But not for mucor.
For many patients affected by mucormycosis, the results are terrible. About half of the patients will die, and the health of many will be permanently damaged.
It is important to diagnose and intervene as early as possible. This includes blood sugar control, urgent removal of necrotic tissue, and antifungal treatment.
Unfortunately, many infections are diagnosed very late and treatments are limited. This was the situation in India before the outbreak of the new crown epidemic, and the current demands on the health system will only make the situation worse.
Controlling these fungal infections requires increased awareness, better testing for early diagnosis, attention to diabetes control, and wise use of glucocorticoids. The patient needs timely surgery and antifungal treatment. But more research is needed on the prevention of these infections.
*Monica Slavin (Monica Slavin) is an expert on lung infections at the Royal Melbourne Hospital and the director of the Infectious Diseases Department at the Peter McCallum Cancer Centre in Melbourne, Australia.
*Karin Thursky is a professor of microbiology at the Peter Dougherty Institute of Infection and Immunity in Melbourne, Australia, and the director of the National Antimicrobial Administration Center.