Leprosy is one of the world's oldest and most feared diseases. It is also one of the most scientifically perplexing and socially challenging.
Yet it is gradually meeting its match. A new report from the World Health Organization shows that 232,857 cases were reported worldwide in 2012. That's a far cry from the five million cases a year recorded until the early 1980s, but still far too many to dream of eradication any time soon.
The good news is that leprosy is increasingly being cornered: Last year, 95 per cent of cases were diagnosed in just 16 countries. India accounts for three in every five cases worldwide, while Brazil and Indonesia are also hotbeds.
Leprosy is one of the world's oldest diseases, but it is still not entirely clear how it spreads. The pathogen, Mycobacterium lepra, is well known; leprosy was one of the first diseases linked specifically to an infectious agent, way back in 1873. (In fact, leprosy is officially called Hansen's disease, after the Norwegian doctor Armauer Hansen, who first viewed the bacterium under a microscope.) But because the organism cannot be cultured in the lab, there is no easy screening test. There is no effective vaccine, and little prospect of one.
The bacterium likely spreads from the infected through coughing and sneezing, but its entry point into the body is not certain. What is clear is that leprosy is not very contagious; most people have natural immunity.
Those who do get infected are difficult to identify. The bacterium can incubate in the body for up to 30 years. The sick are not usually diagnosed until they have serious symptoms, and they tend to live in poor areas with few health services.
The bacterium, M. lepra, attacks nerve endings and destroys the body's ability to feel pain or injury. There is a full range of illness possible, from tuberculoid, a lung infection, through to lepromatous, where much of the body is affected.
In the more serious cases, loss of sensation leads to multiple wounds, which become infected. Contrary to folklore, leprosy does not cause body parts to fall off, but, untreated, it can lead to pretty gruesome deformity to the face and limbs, and blindness.
But the prospects of those infected are better than they've ever been.
A generation ago, millions of lepers were permanently disabled, shunned and condemned to a life of isolation and poverty. But since the WHO adopted a leprosy control plan, more than 15 million have been cured.
While most people who contract leprosy can be cured, the treatment for advanced disease is punishing and costly, at least by the standards of the developing world.
According to the Leprosy Mission Canada, it costs the equivalent of $396 to cure a person of leprosy in the developing world. Patients are treated with a cocktail of antibiotics, a regime that lasts for at least six months, but can stretch into years.
Chasing the bacterium from the body is just the beginning. Most people who contract Hansen's disease end up with serious consequences, physical and mental. They often require surgery to repair damage to skin and limbs, as well as rehabilitation and vocational training.
Attitudes about leprosy are changing, albeit slowly. The disease, though no different from any other bacterial infection, carries with it stigma of biblical proportions. People with the telltale signs of leprosy, particularly the facial wounds and stumpy fingers that advanced disease brings, are shunned. They are usually reduced to begging, and living in abject poverty exacerbates the condition.
In Canada, until the mid-20th century, people with leprosy were quarantined, on the mistaken belief that the disease was highly contagious. "Chinese lepers" were dumped on D'Arcy Island, off the coast of British Columbia, and left to die. "White lepers" were sent to Sheldrake Island off New Brunswick, where they received food and rudimentary care.
Today, Canada sees only a handful of leprosy cases each year, and they are easily treated in the tropical disease units of big city hospitals.
But elsewhere in the world, lazarettos (also known as leper colonies) still exist. So do fear and stigma. As with many misunderstood conditions, the most severe symptom is ignorance.
André Picard