Posted by: Glow-worm PJ28 JAN 2010
The past week (23-29 January 2010) has been World Leprosy Week, drawing attention to one of the oldest scourges of mankind, which has been recognised for more than 4,000 years in various ancient civilisations.
Western attitudes towards the disease come directly from the Bible, in which leprosy is described as a “punishment for sin”. Even though its prevalence steadily declined in Western Europe after a peak in the 14th century, it became epidemic in other parts of the world.
In 1873, Armauer Hansen identified the causative agent as the bacterium Mycobacterium leprae. Contrary to historical opinion, the disease is not easily transmitted. The exact mechanism of transmission is not known. Prolonged close contact and nasal droplet transmission have been proposed, but both remain unproven.
Until the introduction of dapsone in the 1940s there was no effective treatment for leprosy and infected individuals were routinely isolated and segregated from all contact with society. Skin lesions are the primary external signs, and the bacterium causes damage to the nerves of the hands and feet, leading to a loss of sensation with subsequent injury, and fingers and toes may be lost to infection.
It also affects the nerves around the eyes, causing loss of the blinking reflex. The eyes become dry and infected, and the patient may develop many complications, including iritis, cataracts and corneal ulceration.
Today leprosy is in rapid decline as a direct result of the introduction by the World Health Organization, in 1982, of a multidrug therapy (rifampicin, dapsone and clofazimin) to treat multibacillary leprosy. A two-year course usually produces a complete bacteriological cure.
During treatment, the body may react to the dead bacteria, causing pain and swelling in the skin and nerves. This is treated with analgesics and prednisolone and, under controlled conditions, thalidomide.
In spite of the WHO campaign, leprosy still affects more than 10 million people, mainly in Africa, Brazil and the Indian subcontinent. In the past 20 years, 15 million people have been cured, yet over 200,000 new cases are diagnosed each year.
One major concern is the apparent progression of eye damage even after the bacterium has been eradicated, leading eventually to blindness, and this is a focus of current research.