Mucormycosis: Why are Covid-19 patients being affected by black fungus infection?
We now have to cope with another until not so prevalent opportunistic opponent, the so-called ‘Black fungus’ infection, academically dubbed mucormycosis,” said Dr Dhananjaya I Bhat, senior consultant, neurosurgery, Aster RV Hospital.
“The most terrible, cruel expression is Rhino-orbito-cerebral mucormycosis,” he continued (ROCM). With this in mind, we’ll look at a lesser-known organism: the fungus, and its relevance in these volatile and unpredictable times.”
What is a fungus?
These are organisms that are distinct from the plant and animal kingdoms. They are found everywhere in nature, including the soil, plants, decaying organic matter, water, air, and damp places, as well as in humans and animals.
They, along with bacteria, play an important role in our ecosystem by degrading organic matter into simpler forms for plant consumption. “Among them are household yeast, moulds, mushrooms, and a variety of others.
There are approximately 1,44,000 species of fungi (plural for fungus), some of which are pathogenic to humans. Candida, Aspergillus, Cryptococcus, Histoplasma, Pneumocystis, and Mucormycetes are the most common,” he explained.
What types of infection do these fungi cause?
In general, some fungi do not cause infections in humans, but they can cause illness in people with weakened immune systems, which is known as opportunistic infections.
Some common types of a fungal infection include:
- Skin infections such as ringworm
- Nail infections
- Deep cutaneous infections caused by trauma
- Breach in the skin with subsequent fungal implantation and growth
- Sinus infections and deep lung infections Fungi can also affect the gastrointestinal and renal systems, and can cause a full-blown infection as a result of fungus entry into the bloodstream.
If the fungi are so common why is it that we rarely get infected by them?
“We keep these omnipresent organisms at bay and remain infection-free thanks to our body’s defence mechanisms, which are constantly and assiduously fighting them.
When our immune system relaxes its guard, these organisms gain the upper hand and unleash morbid and, in some cases, lethal infections,” he told indianexpress.com.
Who is susceptible to fungal infections?
As previously stated, people with a weakened immune system are more vulnerable to infection. Among the conditions that lower our immunity are:
- *Diabetes: The combination of high blood sugar levels and an acidic environment, as seen in diabetic ketoacidosis, is ideal for the rapid growth of these organisms. Diabetes is also linked to a weakened immune system.
- *Steroid medication raises blood sugar levels and reduces the body’s immune response.
- *Blood cancers, which, once again, result in a faulty immune system
- *Patients on immunosuppressive medications, as seen in organ and haematologic stem cell recipients.
- *Patients who have an excess of iron or are taking deferoxamine (specifically used in iron overdose).
- *Trauma, burns, and malnourished individuals
What is ROCM or Black fungus infection?
Mucormycosis (previously known as Zygomycosis) is a serious but uncommon fungal infection caused by a type of mould known as a micromycete. Molds of the order Mucorales cause rhino-orbital-cerebral-mucormycosis (ROCM).
There are a few subgroups that are commonly involved in this infection, such as Rhizopus, Mucor, and Rhizomucor. These fungi are angioinvasive, which means they invade and destroy the surrounding blood vessels, resulting in tissue necrosis and death.
These moulds are found throughout the environment, and their spores can be found in the air. They become lodged in the nasal cavity and neighbouring sinuses.
When they reach a favourable environment, they settle into the tissue. When the spores germinate, the hyphae (filamentous processes) grow and release destructive juices that digest the host tissue while also providing nutrition to the rapidly growing fungi.
They relentlessly destroy the surrounding host tissue as they grow in the nasal cavity. The nasal cavity and sinuses’ bones are destroyed. The hard palate, orbital bones, and skull base bones are examples of these.
There may be black masses in the nasal cavity and oral cavity. It may cause bulging of the eyes, pain, frozen eye movements, and blindness if it destroys the orbit and enters the eye socket.
Why is it occurring in COVID 19 patients?
Mucormycosis can develop at any time after COVID-19 infection, whether during the hospital stay or several days to a few weeks later. “The COVID-19 causes a favourable change in the host’s internal environment for the fungus, and the medical treatment given unwittingly promotes fungal growth.
COVID-19 wreaks havoc on the airway mucosa and blood vessels. It also causes an increase in serum iron, which is critical for the fungus’s growth. Steroids, for example, raise blood sugar levels.
Broad-spectrum antibiotics kill not only potentially pathogenic bacteria but also beneficial commensals. Antifungals such as Voriconazole inhibit Aspergillosis, but Mucor survives and thrives due to a lack of competition.
Long-term ventilation reduces immunity, and there is speculation that the fungus is transmitted by humidifier water mixed with oxygen. All of the aforementioned factors combine to create an ideal environment for mucormycosis infection,” he explained.
Can there be other fungal infections in COVID 19 patients?
Mucor has not caused as much havoc in Western countries as it has in India. Other fungal infections, such as aspergillosis and candidiasis, have been found to be more common in COVID-19 patients.
Lung infections caused by fungi are difficult to diagnose clinically. The patient has a fever, cough, and shortness of breath, all of which are symptoms of COVID. As a result, overlap creates diagnostic quandaries.
The clinician should be alert to the possibility of fungal infection and have a low threshold for suspicion, especially when a COVID-19 patient is improving and then suddenly develops respiratory failure.
Are these infections life-threatening?
These infections are extremely lethal, and most people will die if they are not treated.
The mortality rate ranges from 25% to 90%. Once the infection has spread to the brain, the mortality rate is extremely high. As a result, early diagnosis and prompt treatment are given a high priority.