My interest in leprosy had a chance beginning. On a family holiday in Crete I spotted in the guidebook an entry about a former leper colony. Spinalonga is a tiny island a few hundred metres off the north coast and we took a small boat out there from the nearby fishing village. It looked like any Greek hamlet, with a church, stray cats, urns filled with basil and geraniums, except that the shops and houses were derelict and, between 1903 and 1957, people with leprosy were sent here to die.

I don’t believe in ghosts, but I found the atmosphere overwhelming. Shutters creaked and shreds of curtain flapped in the breeze as we walked past the crumbling hospital, the communal laundry and the tiny church — remnants of a once thriving community, albeit of the sick. When one of the friends we were with, a dermatologist, explained how slowly the disease sometimes develops and that people could lead relatively normal lives, I felt myself drawn in. The plot for my novel The Island (published in paperback last month) formed easily; it is the story of two sisters, set on the island of Spinalonga, where the lepers are more civilised than the healthy inhabitants.

It was difficult to get right the scientific detail of what is referred to as the “oldest disease in the world”. For an arts graduate without a science O-level to my name, it was daunting. Back in London I went to the London School of Hygiene and Tropical Medicine to see Dr Diana Lockwood, one of the world’s foremost leprologists. I explained that I wanted to write a novel about leprosy and she patiently answered my questions and lent me her precious first-edition textbooks on the subject. My image of a leprosy sufferer, until then defined by the film Ben-Hur, began to change. For a start, I understood that this disease is curable and that to endure it is pure bad luck.

After my book was first published last year I was invited by the Leprosy Relief Association (Lepra) to see its work in India. The medical workers I met were dedicated and kind, and the patients inspiring. People in India don’t seem to feel that they are owed anything and tolerate with great stoicism levels of hardship that Westerners would find impossible to survive.

Rural India has not changed much since biblical times, so perhaps it is unsurprising that leprosy still thrives here. The disease is caused by a bacterium that attacks the skin and nerves of the body’s extremities, resulting in the loss of feeling in hands and feet. In India, men and woman — who walk barefoot, drive their oxen along stony pathways and cook over open fires — are susceptible to blisters, cuts and burns on their hands and feet and that’s what can lead to ulcers and disfigurement (see box).

I met dozens of leprosy patients during my stay. Some had had the disease newly diagnosed and, if it had not been caught in time to prevent them, were facing life with crippling disabilities. Others had been successfully treated and were leading ordinary lives.

Rajani, the vegetable seller, was an example of the latter, though he himself was an extraordinary person. He exuded the kind of contentment normally reserved for someone who has just won the lottery. And he clearly felt he had. Several years ago he was successfully treated for leprosy but, during the course of it, he lost his job, as so often happens to patients who are shunned by their fellow villagers or employers. Lepra, as part of its social and economic rehabilitation programme, lent Rajani some money to set up a vegetable-selling business. He now gets up before dawn, cycles to the nearest big town, buys his stock and sells it at a profit in his own village. His greatest joy is to be able to pay his grandchildren’s school fees, making them the first members of his family to receive an education. As we sat on a finely-carved wooden seat in his mud-brick house, he beamed with pride as he told me about his new project to lease a mango plantation: “I’m glad I had leprosy. It gave me opportunities I would never have had.”

Then there was Jothi, a wisp of a 17-year-old girl, who has been successfully treated but is awaiting an operation to correct paralysis in her hand. When I met her in her home in a remote village in Andhra Pradesh, southeast India, where she lives with her grandmother and mother (also a leprosy sufferer and abandoned by her husband), she was dressed in white. It seemed an unusual colour to wear in a house with mud walls and a dirt floor, but perhaps even more incongruous was her love of Shakespeare. In a large notebook, in spidery writing, she had copied out “All the world’s a stage” from As You Like It, and for each verse had given her own explanation of the text. The notion that “all the men and women (are) merely players” had poweful resonance. Compared with me, she had landed the most difficult of roles. I bit my lip hard as I said goodbye to her.

I met many who were less “lucky”; for example, the case of someone who had ignored early signs and in whom the disease had taken hold. He was 20 and had several large, numb skin patches and when I held his arm I felt the tell-tale rope-textured thickening of the nerve down his forearm. I suspected that his delay in seeing a doctor was the result not merely of lack of education but also of denial. His first thoughts on diagnosis had been: “How will my family react? Will my neighbours shun me?” In this patient, I saw how dangerous stigma can be, almost as destructive as the disease itself.

In the Bible, Leviticus xiii and xiv detail how someone with leprosy should be treated, that he should cry: “Unclean, unclean” and live alone outside his community. Leprosy was believed to be a punishment from God but, even though we know that it is just great misfortune, the stigma remains, even today. I’d like to see those pages removed from every copy of the Bible.

In the few years since my first visit to Spinalonga, I have met hundreds of extraordinary people involved with treatment or fundraising for leprosy. They are driven by the knowledge that this is one of the few big problems in the world that could be resolved. Like them, I would love to see that happen, once and for all.

The Island (Headline Review, £6.99) is available at £6.64: 0870 1608080, timesonline.co.uk/booksfirstbuy