A typically rare fungal infection called mucormycosis has surged in India recently, primarily affecting people recovering from COVID-19.
The fungus invades the sinus and makes its way into the intraorbital and intracranial regions. If its progression is not checked early, 50-80% of patients could die. This type of fungal infection is extremely rare and that it may be affecting people whose immune systems have been damaged by the coronavirus.
What is Mucormycosis
The black fungus infection is called mucormycosis and is caused by a group of molds called mucormycetes that typically live in soil and decaying organic matter.
Mucormycosis is a rare, invasive, fungal opportunistic infection that causes serious, sometimes fatal disease. Over the last 10 years, doctors have only seen a handful of mucormycosis cases in India, reported. This past month, however, tens of thousands of cases have been reported.
Black yeasts, sometimes also black fungi is a perse group of slow-growing microfungi which reproduce mostly asexually. Black yeasts share some distinctive characteristics, in particular melanisation of their cell wall. Morphological plasticity, incrustation of the cell wall with melanins and presence of other protective substances like carotenoids and mycosporines represent passive physiological adaptations which enable black fungi to be highly resistant against environmental stresses.
These black yeasts are believed to be the most resistant eukaryotic organisms known to-date.
Risk factors for Mucormycosis
Those most at risk for mucormycosis have compromised immune systems that make them susceptible to fungal and other opportunistic infections. This includes inpiduals who are currently fighting or have recently recovered from COVID-19 disease
Conditions like HIV/AIDS, long-term corticosteroid and immunosuppressive therapy increase the risk of this disease and the predisposing factor for most of the cases prior to the COVID-19 pandemic. Certain groups of people are more likely to get mucormycosis, including people with diabetes, especially with diabetic ketoacidosis (DKA), cancer, organ transplant, stem cell transplant, neutropenia (low number of white blood cells) , injection drug use , too much iron in the body (iron overload or hemochromatosis and skin injury due to surgery, burns, or wounds. Neonatal prematurity or malnourishment are risk factors associated mainly with gastrointestinal mucormycosis.
Although there have been some reports of mucormycosis in immunocompetent people , it is still regarded an opportunistic disease and specific risk factors for mucormycosis in different patient populations have been identified
Mostly, the disease affects patients with haematological malignancies and prolonged severe neutropenia. Highest at risk for the development of mucormycosis are patients, who either have decreased amounts of mononuclear and polymorphonuclear phagocytes, that would inhibit germination of spores in healthy humans, or whose underlying disease disturbs the function of their phagocytotic cells. In DKA patients, elevated levels of free iron in serum are caused by a release of iron from binding proteins such as transferrin, which is due to a decreased pH level. The dysfunction of glucose and iron metabolism, and regulation of this, was shown to result in decreased phagocytic function.
The breakdown of the skin‐barrier and/or soft tissue injuries, caused by local trauma or burns, is another risk factor for mucormycosis. Cutaneous mucormycosis or soft tissue infections have been linked to the use of contaminated bandages, needles or wooden tongue depressors in the clinical setting. Also, infections have been acquired by insect and spider bites or surgical interventions.
Natural Disasters
Some cases have been reported where patients suffered from cutaneous mucormycosis who survived natural disaster such as tornadoes, hurricanes, tsunamis or volcanic eruptions, adding the occurrence of ‘natural disasters’ to the list of putative risk factors for mucormycosis .
The link between natural disasters and subsequent fungal infections in disaster-affected persons has been increasingly recognized. Fungal respiratory conditions associated with disasters include coccidioidomycosis, and fungi are among several organisms that can cause near-drowning pneumonia. Wound contamination with organic matter can lead to post-disaster skin and soft tissue fungal infections, notably mucormycosis.
Climate change could lead to increased disaster-associated fungal infections. Fungal infections are an often-overlooked clinical and public health issue, and increased awareness by health care providers, public health professionals, and community members regarding disaster-associated fungal infections is needed.
Virulence Traits
To understand mucormycosis in more detail, it is of importance to obtain detailed knowledge about putative virulence traits of the causing agents, as well as to understand their interaction with the host immune system.
The small conidial size of A. fumigatus is often regarded as a putative virulence factor because the size allows conidia to enter the host via respiration. Spore size of the Mucoromycotina is variable, depending on the species 3–11 μm, but in general bigger than those of A. fumigatus for example. Still, they can be inhaled and cause disease in the human lungs.
The secretion of proteases, may contribute to an easier invasion of host tissue and increase host damage.
Another virulence factor is iron acquisition , as iron is an essential element for fungal cell growth and development. Low iron concentrations in the host environment, achieved by bound iron to proteins, such as transferrin, ferritin and lactoferrin, is an effective defence strategy against invading microorganisms.
How Does the Fungal Infection Spread?
Mucormycosis is not contagious, and therefore, it cannot transmit between people and animals. Inpiduals contract this infection by coming in contact with the fungal spores in their environment.
You can contract the fungus by inhaling the mold spores or when you come into contact with them in things like soil, rotting produce or bread, or compost piles. If inhaled, the spores can infect the lungs or sinus. If the fungus enters the skin through a cut, scrape, burn, or other types of skin trauma, mucormycosis can also develop on the skin. The infection can subsequently spread to the bloodstream, and reach organs like the brain, heart and spleen as well.
While most cases of mucormycosis are sporadic, outbreaks of mucormycosis have occurred in the past. In healthcare settings, healthcare-associated mucormycosis outbreaks have been linked to adhesive bandages, wooden tongue depressors, hospital linens, negative pressure rooms, water leaks, poor air filtration, non-sterile medical devices, and building construction.
Symptoms of Mucormycosis
Mucormycosis can affect different parts of the body, showing different sets of symptoms. If the infection grows in the sinuses and brain, symptoms include fever, one-sided facial swelling, headache, and nasal or sinus congestion. If your lungs are affected by the fungus, you can experience cough, chest pain, and shortness of breath.
When mucormycosis attacks the digestive system, you may experience abdominal pain, nausea and vomiting, and gastrointestinal bleeding.
Tips to Lower the Risk of Mucormycosis
It’s difficult to avoid breathing in fungal spores because the fungi that cause mucormycosis are common in the environment. There is no vaccine to prevent mucormycosis.
For people who have weakened immune systems, there may be some ways to lower the chances of developing mucormycosis. Protect yourself from the environment. Try to avoid areas with a lot of dust like construction or excavation sites. If you can’t avoid these areas, wear an N95 respirator (a type of face mask) while you’re there.
Avoid direct contact with water-damaged buildings and flood water after hurricanes and natural disasters. Avoid activities that involve close contact to soil or dust, such as yard work or gardening. If this isn’t possible, wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas. Wear gloves when handling materials such as soil, moss, or manure.
To reduce the chances of developing a skin infection, clean skin injuries well with soap and water, especially if they have been exposed to soil or dust.
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