Through all this, Lokhande did gain one thing: resistance. Yet this was no victory—the erratic prescription of antibiotics had made her resistant to tuberculosis drugs, and by 2014, she was diagnosed with extensively drug-resistant, or XDR, TB, a nastier version of the disease against which most powerful antibiotics do not work. Lokhande’s doctor gave up, advising her mother to take her home and pray.

Lokhande’s story illustrates that developing new treatments is only one part of the battle to combat infectious diseases—whether ancient bacteria such as tuberculosis, or COVID-19, the disease caused by the novel coronavirus. In cases such as Lokhande’s, in places such as India, poor regulation, improperly functioning medical systems, and wayward doctor training are in many ways more-difficult hurdles to scale.

“Everything that could go wrong, went wrong,” she told me.

In November 2014, Lokhande was wheeled into Zarir Udwadia’s clinic in Mumbai’s Hinduja hospital. Then 27, she weighed barely 60 pounds, and her clothes hung over her in no defined shape. Udwadia, one of India’s leading TB experts, told me he was appalled at the poor treatment Lokhande had received, and immediately recommended one of two relatively new drugs designed to treat XDR TB.

After years in which her body had been battered, her finances crippled, her life upended, Lokhande’s struggle still had far to go.

Tuberculosis is an ancient disease: In the age before modern science, it was called consumption, so named for what it did to a person’s body—consuming it. When people contract tuberculosis, they rapidly lose weight, start coughing up blood, and turn pale, as if life is being slowly sucked out of them. (One of the disease’s other historical names was the white plague, for the anemic pallor of those infected.) Today, TB, which is transmitted through the air and is easily passed between people, is the leading cause of death from infectious diseases worldwide. The World Health Organization estimates that 1.8 billion people, or about a quarter of the world’s population, are latent carriers of TB.

Like many things in India, TB exists here on an enormous scale. Of the 10.4 million new TB cases reported globally each year, 2.8 million are in India. The explosion of TB has become so grave in India’s megacities, where sneezing or coughing etiquette is not commonly practiced, that Udwadia has warned it is deadlier than Ebola. Some 480,000 Indians die of TB each year, more than 1,300 each day. During the peak of the AIDS epidemic, South Africa, the worst-affected nation in the world, reported fewer deaths per day.

Yet a crucial distinction between TB and HIV, the virus that causes AIDS, is that TB is curable. Most properly organized treatment plans for TB last at least six months, and typically result in a full recovery. A poorly designed plan, however, can be dangerous, leading to the development of long-term drug resistance.