AHMEDABAD, INDIA (NYTIMES) - In the stifling, tightly packed medical ward at Civil Hospital, the ear, nose and throat specialist moved briskly from one bed to the next, shining a flashlight into one patient's mouth, examining another's X-rays.
The specialist, Dr Bela Prajapati, oversees treatment for nearly 400 patients with mucormycosis, a rare and often deadly fungal disease that has exploded across India on the coattails of the coronavirus pandemic.
Unprepared for this spring's devastating Covid-19 second wave, many of India's hospitals took desperate steps to save lives - steps that may have opened the door to yet another deadly disease.
"The pandemic has precipitated an epidemic," Dr Prajapati said.
In three weeks, the number of cases of the disease - known by the misnomer "black fungus", because it is found on dead tissue - shot up to more than 30,000 from negligible levels.
States have recorded more than 2,100 deaths, according to news reports.
The federal Health Ministry in New Delhi, which is tracking nationwide cases to allot scarce and expensive anti-fungal medicine, has not released a fatalities figure.
The coronavirus pandemic has drawn stark lines between rich nations and poor, and the mucormycosis epidemic in India stands as the latest manifestation.
During the second wave, which struck India in April, its creaky, underfunded medical system lacked beds, oxygen and other necessities as infections and deaths soared.
The mucormycosis epidemic adds even more urgency to the difficult task of protecting India's 1.4 billion people.
Only a small fraction have been vaccinated against the coronavirus, and they remain vulnerable to a third wave and the consequences that could follow.
"Mucormycosis will tail off and go back to baseline as the Covid cases subside," said Dr Dileep Mavalankar, an epidemiologist.
"But it may come back in the third wave unless we find out why it is happening."
Many doctors in India think they know why. The bone-and-tissue-eating fungus can attack the gastrointestinal tract, the lungs, the skin and the sinuses, where it often spreads to the eye socket and the brain if left untreated.
Treatment for the disease involves complex, often disfiguring surgery and an uncommon and expensive drug, contributing to a mortality rate above 50 per cent.
Mucormycosis is not passed from person to person.
It develops from commonplace spores that sometimes build up in homes and hospitals.
Doctors believe India's crowded hospitals, and their dire lack of medical oxygen, left the fungus an opening.
Without enough oxygen to go around, doctors in many places injected patients with steroids, a standard treatment for doctors battling Covid globally.
They can reduce inflammation in the lungs and help Covid patients breathe more easily.
Many doctors prescribed steroids in quantities and for durations that far exceed World Health Organisation (WHO) recommendations, said Dr Arunaloke Chakrabarti, a microbiologist and co-author of a study examining the causes of India's mucormycosis outbreak.
Those steroids may have compromised patient immune systems and made Covid-19 patients more susceptible to fungal spores.
The steroids may have also dangerously increased blood sugar levels, leaving people with diabetes vulnerable to mucormycosis.
It could also increase the chance of blood clots, leading to malnourished tissue, which the "fungus attacks", Dr Prajapati said.
Desperate doctors may not have had the chance to ask patients about whether they had diabetes or other conditions before resorting to steroids.
"Doctors hardly had any time to do patient management," Dr Chakrabarti said.
"They were all looking at how to take care of the respiratory tract."
According to the Health Ministry, about four out of five mucormycosis patients have had Covid-19. More than half have diabetes.
Mr Alok Kumar Chaudry, a 30-year-old engineer with surgical tape over his left eye and hooked up to an IV drip at Civil Hospital, is one of those with mucormycosis who first came down with Covid.
He was studying for India's civil service exam in April in New Delhi when the second wave hit.
After testing positive for the coronavirus, and with hospital beds, drugs and oxygen scarce, he jumped onto a train to his older brother's home in rural Gujarat.
There, his oxygen levels plummeted to a potentially lethal 54 per cent.
After two weeks on oxygen support and steroids at a local hospital, he recovered from Covid-19 but developed an acute headache on the left side of his brain.
Doctors thought that steroids may have caused it and that it would go away.
"Suddenly vision in my left eye went blank," Mr Chaudry said.
An MRI exam showed mucormycosis. The doctors said they would have to remove his eye.
He went to Ahmedabad's Civil Hospital for a second opinion.
Five specialists oversaw a surgery that involved scraping away the dead tissue in his sinus tract.
To clear out remaining infection, he received a 15-day course of amphotericin B, an anti-fungal medication.
Dr Chakrabarti said that if Mr Chaudry kept his eye, he could still lose his life, since surgeons couldn't remove the thin layer of infection behind his eye without removing the eye itself.
"I've lost vision in my left eye, my studies have suffered," Mr Chaudry said. "Definitely I want to know why mucor has formed. If it's faulty treatment, then someone is responsible. If it's the wrath of God, what can I do?"
The study that Dr Chakrabarti co-authored, published this month by the US Centres for Disease Control and Prevention, said that heavy use of steroids, the correlation with diabetes and the unsanitary conditions at some hospitals had played a role.
Even before the pandemic, India recorded about 50 mucormycosis cases a year, compared with, on average, a single case every two years in the United States and Western Europe.
Environmental conditions play a part, as does the incidence of diabetes - India has more than twice as many people with the condition as the United States does.
Usually in India, mucormycosis afflicts people with diabetes who are either unaware of their condition or who are not taking insulin properly.
But in the current outbreak, many patients had no history of diabetes.
The common denominator was a Covid-19 infection treated with steroids, clinicians and researchers say.
The government in Ahmedabad, in Gujarat, declared mucormycosis an epidemic in May. Other states have followed.
Whether patients live or die often depends on how quickly they undergo debridement surgery that removes the fungus and then start a two-week course of amphotericin B.
Prime Minister Narendra Modi, who is from Gujarat, described the fungal disease as a new "challenge" and said it was "important to create systems to tackle it".
India makes small supplies of amphotericin B, which can be obtained free of charge at some public hospitals.
But because supplies are limited, India is importing it from the United States, where it costs about US$300 (S$403.42) per vial.
Each patient needs 60 to 100 vials. Gilead Sciences, the American manufacturer, has donated about 200,000 vials.
Doctors are using cheaper drugs that are as effective but more toxic, posing a risk of kidney damage.
"That's a very painful choice," said Dr Atul Patel, an infectious diseases specialist at the private Sterling Hospital in Ahmedabad who has treated dozens of mucormycosis patients in the outbreak.
Dr Patel, another of the study's authors, said that steroids, which in India are commonly prescribed for routine ailments such as diarrhoea or fever, had been prescribed to Covid-19 patients with mild infections who didn't need them.
That was the case for one of Dr Patel's patients, Ms Ambaben Heerabhai Patel, 60, the matriarch of a farming family in rural Gujarat, who is paying about US$700 a day for anti-fungal treatment and other services at Sterling.
It's a steep cost, but Ms Ambaben Patel had seen Dr Patel - no relation - for previous health issues related to her diabetes.
After back-to-back infections of Covid-19 and then mucormycosis, she did not want to take any chances.
Arriving at the hospital on May 17 with an an intense headache and facial numbness, Ms Ambaben Patel said in early June from her private room at Sterling Hospital that she felt well for the first time in more than a month.
Of Dr Patel, she said, "he's like my God".