Mr. Chowla recalled an awareness session that Lepra held in a remote village in September of 2017. About one-quarter of the village’s 1,000 residents attended and were examined, and nine cases were diagnosed. When Dr. Kumar heard about the cases, he immediately launched a district-wide awareness campaign. By November 2018, the reported prevalence of leprosy in that district had more than doubled, a sign that health officials were becoming more successful at finding hidden cases.

The numbers of cases must first go up, as such cases are revealed, before they can go down, Dr. Kumar said. More important is that the number of visible deformities has fallen by 25 percent. “It means we are preventing disability,” he said. “We are detecting cases early. And it also means we have cut down transmission at the community level.”

He has embraced the WHO’s latest targets for leprosy, to be achieved by 2020: To decrease the number of new patients diagnosed with visible deformities to less than one per million, and the number of children with disabilities to zero.

With luck, Siddamma’s children received treatment early enough to avoid disability. But it came at the cost of great effort. Few doctors in India are familiar with leprosy, and they are far between.

To reach the leprosy clinic, Siddamma and her children woke early, took a three-wheeler from their home to a bus stop several miles away, then took a long bus ride to the clinic. The cost of the ticket was not trivial. Siddamma was tired. At one point, she unconsciously lapsed into her native Kannada from her patchy Telugu, the language spoken at the clinic.

And she was worried about her youngest daughter who, despite three months of treatment, still has many patches on her arms. To make sure she is cured, Siddamma would need to make the long journey at least once more.