INTRODUCTION
Mucormycosis is a very rare infection. It is caused by exposure to mucor mould which is commonly found in soil, plants, manure, and decaying fruits and vegetables. It affects the sinuses, the brain and the lungs and can be life-threatening in diabetic or severely immunocompromised individuals, such as cancer patients or people with HIV/AIDS.
Doctors believe mucormycosis, which has an overall mortality rate of 50%, may be being triggered by the use of steroids, a life-saving treatment for severe and critically ill Covid-19 patients.
Steroids reduce inflammation in the lungs for Covid-19 and appear to help stop some of the damage that can happen when the body’s immune system goes into overdrive to fight off coronavirus. But they also reduce immunity and push up blood sugar levels in both diabetics and non-diabetic Covid-19 patients.
It’s thought that this drop in immunity could be triggering these cases of mucormycosis.
WHY BLACK FUNGUS HITS COVID-19 PATIENTS?
Mucormycosis can occur any time after COVID-19 infection, either during the hospital stay or several days to a couple of weeks after discharge.
The COVID-19 causes favourable alteration in the internal milieu of the host for the fungus and the medical treatment given, unwittingly also abets fungal growth. COVID-19 damages the airway mucosa and blood vessels. It also causes an increase in the serum iron which is very important for the fungus to grow. Medications like steroids increase blood sugar. Broad-spectrum antibiotics not only wipe out the potentially pathogenic bacteria but also the protective commensals. Antifungals like Voriconazole inhibit Aspergillosis but Mucor remains unscathed and thrives due to lack of competition. Long-term ventilation reduces immunity and there are speculations of the fungus being transmitted by the humidifier water being given along with oxygen. All the above make for a perfect recipe for mucormycosis infection.
SYMPTOMS OF BLACK FUNGUS
Nasal blockage, bleeding, discharge from the nose are initial features of mucormycosis. On endoscopic visualization of the nasal cavity an unmistakable black eschar (slough or dead tissue) coated masses will be present which gives away the diagnosis. As the disease progresses the palate may be destroyed as a large black necrotic mass may be seen on opening the mouth. When the orbit is involved there will be proptosis (protrusion of eyeball), loss of movements of the eyeball with consequent double vision. Eye pain, redness with blindness can follow. If the brain is invaded due to blood vessel blockage there will be strokes, hemorrhages, and even death. Patients can also have headaches, drowsiness, limb weakness, seizures and even death.
In lung mucormycosis clinical features are similar to COVID-19 with fever, cough, shortness of breath, making clinical diagnosis difficult. Suspicion of fungal infection must be considered when a patient despite getting appropriate medications is not improving or was improving and has unexplained deterioration. CT chest helps in diagnosis by revealing additional lung lesions. Diagnosis is by microscopic evaluation of the bronchopulmonary lavage aspirate.
TREATMENT OF BLACK FUNGUS
Once a clinical and radiological diagnosis is made, endoscopic evaluation of the nasal cavity can confirm a fungal lesion. Immediate surgical debulking is a must. The surgery can be radical and disfiguring but is acceptable considering the existential crisis of leaving behind any residual tissue. The entire nasal cavity needs to be scoured and all fungal, necrotic tissue needs to be removed. If the orbit is involved surgeries as drastic as exenteration of the eye socket contents may be required. Intracranial decompression may be required if the infection has spread to the brain. Surgical intervention should be undertaken a couple of hours after diagnosis.
In tandem, medical management with antifungal drugs, namely injection Liposomal amphotericin-B needs to be instituted. Older form amphotericin deoxycholate is significantly nephrotoxic. However, the liposomal cousin is safe and effective. Posaconazole tablets/ suspension and intravenous forms are available and are used in lieu of amphotericin if the latter is not tolerated by the patient. Following several weeks of intravenous medication depending on the response the patient is put on oral posaconazole sustained release tablets for several months. Isavuconazole is also an alternative drug that can be used. Drugs are stopped after clinical and radiological clearance of the disease.
During treatment, judicious use of steroids (keeping blood sugar levels under control), antibiotics, and other antifungal drugs need to be done.
PREVENTION OF BLACK FUNGUS
Prevention is always better than cure.
In hospital:
*Maintenance of good hygiene and cleanliness is a must. Regular oral hygiene care with mouthwash, povidone-iodine gargles must be done.
*While administering oxygen, water for humidification must be sterile and there should be no leakage from the humidifier.
*Steroid usage must be limited to no more than necessary with strict blood glucose control.
*Unnecessary use of broad-spectrum antibiotics, antifungals should not do as this removes the normal commensal flora resulting in the growth of unwanted organisms due to lack of competition.
Once discharged:
*Stay indoors as much as possible
*Regular exercises
*Control of blood sugars
*At home, the surroundings must be clean and free from dust and dampness
*Maintain oral and nasal hygiene
*While going out always wear an N-95 mask
*Avoid construction areas, fields, grounds.
*Soil and plants are the areas that abound with fungi. Hence better to avoid working with soil, gardening. If unavoidable, masks, rubber gloves, and boots are a must.
The key take-home messages are opportunistic fungal infections are occurring in COVID-19 patients, awareness among health care providers and the public is important, early diagnosis and aggressive treatment are paramount for improving outcomes in an otherwise dismal disease, together we can definitely win this battle against COVID 19 and mucormycosis
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