Human Corona Viruses (HCoV) are the type of viruses that cause infections mainly in gastrointestinal and respiratory systems. The first discovered human corona viruses were HCoV‐229E and HCoV‐OC43 from the nasal cavities of human patients who were suffering from common cold, in 1960s.1 Other human coronaviruses include SARS‐CoV (in 2003), HCoV NL63 (in 2004), HKU1 (in 2005), MERS‐CoV (in 2012), and the latest one SARS‐CoV‐2 (in 2019) resulting in coronavirus disease (COVID-19).2 Globally, there have been 173,674,509 confirmed cases of COVID-19, including 3,744,408 deaths reported as on June 09, 2021. As of June 10, 2021 there were 1,167,952 active cases in India while 27,655,493 people had recovered from the disease.3 While the national COVID-19 recovery rate dropped to 94.77%, the case fatality rate was down to 1.23% according to the MoHFW.

In the year 2021, multiple challenges have been faced while treating Covid-19 infections, including Mucormycosis (black fungus). Mucormycosis is an opportunistic fungal infection that belongs to the zygomycete family and is ubiquitous in the environment. The major route of infection is via inhalations of spores of Rhizopus oryzae a common cause of rhino-orbital-cerebral form of infections, which spread to the paranasal sinuses and lungs. These moulds are generally found in soil, plants, manure, decaying fruits and vegetables. Mucormycosis is a rare but severe and eventually fatal fungal infection that usually affects patients with altered immunity. In general, these fungi are non-pathogenic in immune competent patients but in the case of patients immune compromised by either steroids or any other co-morbidities like diabetes, solid cancers, malignant and hematologic disorders may become life-threatening. Other risk factors including organ transplantation and high levels of iron in serum may increase the risk of black fungus mortality.4

In covid-19 patients, especially those who need oxygen support, the immune system may become weak due to inflammatory storm or usage of steroids. This may pave the way for opportunistic infections including mucormycosis. The common symptoms of this infection include discoloration of the nose and tongue, redness in the eyes, blurred vision, difficulty in breathing, chest pain, cough, fever, headache, black lesion inside the mouth, and vomiting. Diagnosis is usually made by clinical suspicion and histopathological examination. As per recent reports in India, the number of people dying from black fungus is steadily increasing and experts are referring to it as 'pandemic within COVID-19 pandemic'.

In India more cases were noticed in the second wave of Covid-19 than in the first wave with increased mortality rate. The major complications faced with mucormycosis in the second wave were reduced oxygen levels, difficulty in breath and other respiratory tract associated problems like pneumonia and Acute Respiratory Distress Syndrome. At present in India, the patient who underwent long oxygen supportive therapy are more prone to be infected with mucormycosis.

During the second wave of Covid-19 pandemic the very first case of mucormycosis or black fungus infection was reported at Gujarat in a 15-year-old boy who recovered successfully from Covid-19 and got discharged. Later on the cases were reported in more than 18 states of India.5 Auraiya district in Uttar Pradesh has reported the first death caused by mucormycosis. The highest death rate was recorded in Rajasthan. India has recorded more than 12,000 cases of mucormycosis, and over 300 deaths were recorded in the past few months.5 Most of the cases are reported from Gujarat, Maharashtra, Rajasthan, Karnataka, Andhra Pradesh, Haryana and Telangana as per the latest government reoprts.6 Ten states in India reported large number of mucormycosis cases; those are graphically represented in Fig. 1.

Fig. 1.

Mucormycosis cases across India. MP= Madhya Pradesh, AP= Andhra Pradesh.

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According to literature, it is clear that animals/humans with decreased number of phagocytes or having impaired phagocytic function are at higher risk of black fungus infection. Therefore, patients with severe neutropenia are at increased risk of developing the infection.7 In contrast, as HIV/AIDS patients do not seem to be at increased risk for developing black fungus infection, it suggests that neutrophils play a key role in the inhibition of fungal spore proliferation, but not necessarily T lymphocytes. In the condition of diabetic ketoacidosis, phagocytes are dysfunctional and have impaired chemotaxis and defective intracellular killing by both oxidative and non-oxidative mechanisms. The pulmonary alveolar macrophages harvested from lungs of immunocompetent mice are able to inhibit the germination of fungal spores. But the same pulmonary alveolar macrophages isolated from immunosuppressed mice are unable to inhibit the fungal spore germination in in-vitro and in-vivo experiments.8 The mechanisms by which phagocytes turn dysfunctional by diabetes mellitus and corticosteroids need to be determined.8 One of the essential elements for cell growth and development is iron. Therefore, pathogens use some processes for obtaining iron from the host. Transferrin, ferritin, and lactoferrin are the carrier proteins to which the excess iron is bound in hosts and avoids toxic effect of free iron by reducing the excess free iron levels in serum. This is the unique host defense mechanism against bacteria, virus and even fungus especially mucorales because they cannot grow in normal serum unless iron is added exogenously.

To treat severe mucormycosis infection, the patient should be strictly monitored by a team of health specialists including microbiologists, internal medicine specialists, neurologists, ENT specialists, ophthalmologists, dentists, surgeons, etc. In India the first line drug being used for treating mucormycosis is liposomal amphotericin-B and approximately 20 vials of this antifungal injection may be required to treat a single infected person. In India, the current price for each vial is around Rs.5000-6000, according to reports. The second line drug is Posaconazole. Doctors are warning that all these medicines should only be taken under strict medical supervision.

In few cases surgical removal of infected tissues may be required. At the hospital MGM Health care located at Chennai, Tamilnadu a person diagnosed with black fungus in the right naso-orbital region involving sinuses was saved by a surgery performed with the help of multiple angled high-definition endoscopes. Of a total of 700 cases reported in Jaipur over 200 patients underwent jaw removal surgery.