The Ancient Armadillo Fights a War Against Disease

The Ancient Armadillo Fights a War against Disease

By Mr Ghaz, December 12, 2009

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The Ancient Armadillo Fights a War against Disease

Few creatures are stranger in appearance than the curious nine-banded armadillo, one of the last remaining members of the ancient order Xenarthra, which flourished 55 million years ago. Until recently this engaging animal was best known for its ‘armor plating’ – two leathery shields, one in front and the other at the back, connected by nine or more horny bands – that protects it from predators. But in recent years this survivor of prehistoric times has been helping scientists solve one of the world’s most pernicious problems: leprosy.

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Today leprosy is not as rare as in often thought. In many parts of the world it is still a major crippling disease and in its most severe form can lead to blindness, disfigurement, and deformity. In Africa and Southeast Asia, as many as 15 million people are thought to be affected, and it is reported that approximately 5,000 people in the United States are afflicted with it.

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Although drugs can be used to control the more severe forms of leprosy, no complete cure has ever been found and, until now, the possibility of a vaccine has been remote. Although Armauer Hansen, a Norwegian scientist, had identified the organism responsible for the disease (Mycobacterium leprae) in 1873, the bacillus refused to grow in the laboratory. Consequently, tests that might have led to a vaccine could not be carried out. Nor could the bacillus be grown or tested in animals, because scientists could not find any that were susceptible to leprosy.

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New hope of eradicating leprosy worldwide came in 1972 when two American scientists, Eleanor Storrs and Waldemar Kirchheimer, discovered the link between leprosy and armadillos.

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Storrs, who had been studying armadillos for some time, believed that they might make suitable candidates for experiments on leprosy. First, armadillos had a lower body temperature than any other mammal, and it was known that leprosy attacks the cooler extremities of the body. Also, armadillos lived up to 15 years – long enough to develop the disease, which has a protracted incubation period. Finally, their tendency to produce litters of identical quadruplets offered a perfect opportunity to rest a long-held theory that susceptibility to leprosy might be inherited.

Long-Awaited Proof

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In 1970 Storrs joined forces with Kirchheimer, who was with the U.S. Public Service Hospital at Carville, Louisiana, and began to carry out experiments on armadillos. In the beginning, unrelated animals captured in the wild were inoculated with the leprosy bacillus. Proof that armadillos were susceptible to the disease came when one of the animals developed it and died.

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A few years later, the researchers inoculated 11 sets of quadruplet armadillos. Within six months one set of four had developed leprosy almost simultaneously. Since the odds of this happening by chance were extremely low, earlier theories of inherited susceptibility were supported.

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The implications of the work of Storrs and Kirchheimer for human sufferers are considerable. Infected armadillo tissue provides a plentiful source of a substance known as lepromin; when injected into a leprosy patient, it indicates how likely he or she is to be effected by the disease. Therefore, extreme cases can be singled out at an early stage and the progress of the disease monitored. In 1974 the World Health Organization started a program to develop a vaccine based on armadillo-grown bacilli. Trials on human beings have already begun in Venezuela and in Malawi (formed Nyasaland) in Southeast Africa.

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Dr. Tom Gillis of the National Hansen’s Disease Programs says that it is safe to say that in the next five years, there will be one to two new vaccines for tuberculosis that might include a leprosy component. As far as a vaccine exclusively for leprosy, we might see one in the next 5-10 years, then it would take 5-10 years to follow up on it and test it. His estimate is that it could be about 10-20 years before we see an official leprosy vaccine that is universally accepted worldwide.

If the vaccine proves successful, the world may begin to eradicate this centuries-old affliction – thanks to nature’s knight in shinning armor, the nine-banded armadillo.