Covid-19 patients with diabetes most at risk of mucormycosis
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Why do some Covid-19 patients develop mucormycosis and not others? Several hypotheses have been proposed to explain this in the past, but a new study conducted by AIIMS has listed surprising risk factors that leave an individual more susceptible to the deadly black fungus infection.

Diabetes, the study suggests, is the biggest risk factor for mucormycosis infection, followed by the use of steroids. The study also says that prolonged use of surgical or cloth masks and repeated RT-PCR tests, which involves taking nasal swab samples, also increase the odds of contracting black fungus. Notably, oxygen supplementation or hospitalisation did not affect the risk of CAM (coronavirus disease associated with mucormycosis), adds the study. Zinc therapy, probably due to its utility in immune function, was also found to be protective.

For the study, the medicine department selected 352 patients diagnosed with Covid between April and May, the period when the second Covid wave was at its peak. Of them, 152 were under treatment for mucormycosis while the rest had recovered from Covid without suffering the fungal infection. The patients and their families were asked about the various risk factors hypothesised to be responsible for mucormycosis. It was discovered that 92% of the patients who developed mucormycosis had diabetes. In the non-mucormycosis category, only 28% were diabetic.

A third (36%) of the patients with mucormycosis were newly diagnosed with diabetes during hospitalisation for Covid, based on raised blood sugar levels or abnormal HbA1c levels, researchers said. “The reason behind the increased vulnerability of diabetics to the fungal infection could be pre-existing low immunity worsened by use of steroids during the treatment. Therefore, control of co-morbidities is very important in such patients,” said Dr Neeraj Nischal, associate professor, department of medicine.

The researchers found that the use of cloth masks for more than four hours and of surgical masks for more than six hours were associated with a higher risk of CAM compared with the use of such masks for less than two hours or N95 masks for any duration. The study said the findings on the association between mask use and mucormycosis were similar even when healthcare workers — 40 were included in the study — were excluded as confounders who were more limited to the control group of patients and used N95 exclusively.