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With unlikely help from armadillos, experts are developing a vaccine aimed at combating leprosy, one of the world's oldest recorded and most dreaded diseases.

The vaccine being tested in Malawi and Venezuela could help reduce the disease, which still afflicts about 15 million to 20 million people worldwide, according to experts at an international leprosy conference in The Hague this month."We expect that the vaccine will work both on people who have never been infected and on those who are in a high risk group because they are already infected," said Shaik Noordeen, head of the World Health Organization's leprosy program.

Some 30,000 people have been innoculated with the vaccine in Venezuela, another 120,000 are receiving it in Malawi and a third project involving some 300,000 recipients is expected to begin in India next year, he said in an interview.

The vaccine combines KLM (Killed Mico-bacterium Leprae) from armadillos with a tuberculosis vaccine known as BCG (Bacillus Calmette-Guerin).

"We have evidence that BCG is imparting some protection against leprosy in some populations. We are trying to see if combining it with KLM will be more effective," said Paul Fine, coordinator for the project in Karonga, in north Malawi.

Leprosy, described in the Veda scriptures of India as early as 800 B.C., attacks the nerves, causing loss of sensation in the face, arms and legs. Eventually limbs may become deformed. Some forms are contagious, others not.

A vaccine against leprosy has long defied immunologists, who until recently have been unable artificially to produce the bacteria that causes the disease.

It was only after a scientist in Louisiana in the early 1970s found that the bacteria could be grown in armadillos - suitable because of their low body temperature - that experts could produce enough antigens to develop a vaccine.

"Until the armadillo came along, leprosy was in the dark ages," said Fine, an epidemiologist at London University's School of Hygiene and Tropical Medicine.

"Aside from scientific problems, developing a vaccine was held up by social factors. Leprosy has a stigmatizing image and lots of people don't know it exists anymore," he said.

WHO funding helped allay the high cost of armadillos, he said.

Several experts said that if the vaccine turned out to be effective, a method to produce the antigen using new genetic engineering techniques could probably be developed.

Because leprosy has an incubation period of up to 20 years, it will take years to discover whether the vaccine is effective. Scientists hope to have some preliminary results in two to three years.

But even if the vaccine works, it is unclear how widely it will be used. A combination of drugs and surgery has been successful in curing the disease in many victims. What remains to be seen is whether it is more viable to prevent the disease than treat the afflicted.