Leprosy treatments developed
Leprosy is a disease with a long history, with evidence dating back to 4000 BC in ancient Egypt and numerous references in the Bible.
As the M. leprae bacterium is not possible to grow in cultures, early research relied on the limited infection observed in the footpads of mice.This was an important system in screening drugs for treating leprosy. The anti-bacterial effect of clofazimine was discovered using the mouse footpad technique. The anti-tuberculosis drug rifamycin was discovered to be effective against M. leprae in mouse footpad. It also yielded further insights into the activity of dapsone, which had been in use since the 1940s. , Research done on these drugs in mice led to the development of rifampicin, clofazimine and dapsone multi-drug therapy, which was trialled in humans in Malta and recommended by the World Health Organisation in 1982. This combined therapy has been key in reducing the impact of leprosy worldwide and is still used today. The number of cases worldwide has fallen from 5.2 million in 1983 to 182,000 in 2011.
The nine-banded armadillo has become the principal source of M. leprae in vaccine research. The core body temperature of the armadillo is low enough to favour the growth of the leprosy-causing bacterium. In fact, leprosy is endemic among wild armadillos in the US and now form a reservoir of the disease from which humans can become infected.The use of armadillos in leprosy research dates back to the 1970s and has largely been focussed on the development of a vaccine. Using the armadillo, scientists were able to develop an experimental vaccine against leprosy, and have helped our understanding and the development of treatments for the disease. The vaccine development programme ran from the 1970s until the late 1990s when the BCG vaccine, which is given worldwide to prevent tuberculosis, was shown to be similarly effective against M. leprae. Although the vaccine programme eventually proved impractical, studying the purified bacteria led to a much greater understanding of leprosy, including sequencing of its genome. Armadillos also act as a source of bacilli, with bacteria derived from armadillos used in the lepromin skin test that tests for a M. leprae infection.
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