Scientific advances in leprosy research

Scientific Advances in Leprosy Research: Origins of Leprosy on the Trail

14/06/2013

In many parts of the world, especially India, Africa and Brazil, millions of people still suffer from leprosy. Scientists now came closer to the origins of the infectious disease by analyzing the genome of medieval leprosy bacteria.

Common ancestor 4,000 years ago
Although leprosy is considered curable, up to four million people worldwide suffer from leprosy-related mutilation. The symptoms of chronic infectious disease vary greatly from patient to patient. In the early stages it comes to the typical blurred stains on the skin. Previously, the disease was called leprosy, as those affected „exposed“ had to live outside human settlements. Geneticists now rely on the DNA decryption of the pathogen and were able to determine from medieval leprosy bacteria that the genome has changed little over the centuries. In addition, it was analyzed that many of the bacteria go back to a common ancestor, who lived 4,000 years ago, according to the team around the Tuebingen evolutionary geneticist Johannes Krause in the Journal „The research team used five well-preserved medieval skeletons as well as current samples from living leprosy sufferers, who for the first time succeeded in reconstructing complete genomes of the pathogen Mykobacterium leprae from different eras.

Hardly any changes in the last millennia
Over millennia, there have been few mutations in the genome of the pathogen and this allows according to Krause conclusions about the disease. For example, the realization that leprosy was relatively uniformly distributed for millennia and not like the plague has occurred in several pandemics. The strong prevalence of leprosy in the Middle Ages was not due to the pathogen, but to the changing living conditions of the people. The spread had increased when in the 10th century people lived together in ever larger settlements. And by the 14th century, it had been curbed by improved hygiene standards, Krause said. It also became clear during research on the leprosy genome that the DNA of bacteria remains much longer than that of mammals, even under unfavorable environmental conditions. „This should make it possible to trace the disease back to its prehistoric origins, "said Krause.

Many people without access to effective medicines
Insights into origins and changes in the disease may be relevant to medicine. For example, knowing how fast bacteria mutate makes it easier to gauge how fast they become resistant to new antibiotics. The professor said it was not clear yet whether there would be research projects that would try to harness the DNA decryption of the leprosy pathogen to medicine. However, it is conceivable that a suitable antibiotic could be determined for each patient with the aid of simple DNA analyzes. More than 200,000 people worldwide still suffer from leprosy each year. According to the German Leprosy and Tuberculosis Relief Agency (DAHW), up to four million people have mutilations caused by leprosy. The disease is most common in India but also in Africa and South America, such as Brazil. Leprosy cases also occur in the USA, where armadillos are responsible for diseases. In Europe, there is still the Sanatorio San Francisco de Borja, specially set up for the treatment of leprosy patients, in the Spanish village of Fontilles in the hinterland of the Costa Blanca. Basically leprosy is curable but especially in the poor regions of the world many people do not have access to the helping medicines. With the help of the remedies, the leprosy pathogens could be completely killed in 6 to 18 months. (Sb)