Its gruesome symptoms mean leprosy has a particularly nasty reputation, despite being relatively easy to treat. However, that might be about to change.
An international team of scientists reporting in the journal Nature Communications has surveyed the genomes of over a hundred strains of the leprosy bacterium, Mycobacterium leprae. Their findings suggest that more and more strains of bacteria have hypermutated to become resistant to traditional drugs.
This new research set out to isolate, sequence, and analyze the genomes of 154 different strains of M. leprae from across the world. Out of these, 8 strains were found to contain a large number of random mutations that have allowed them to develop a resistance to multiple drugs. It’s hard to tell exactly, but the mutations have probably accumulated over the past few years or perhaps decades.
“It’s a fascinating survival strategy against antibiotics,” Andrej Benjak, the study’s lead author, explained in a statement. “Disrupting DNA repair will result in a storm of random mutations, increasing the chance that the right gene mutates at the right spot and lead to drug resistance. But random mutations can be deadly, so it’s like a desperate, genetic Russian roulette for the bacterium.”
Leprosy is an infectious disease that affects the nerves, eyes, and airways. Sometime after becoming infected, sufferers will experience a loss of sensation and permanent damage to the skin, nerves, and limbs. Eventually, this can develop into disability and deformations.
Ancient texts, such as the Hindu scripture the Atharva Veda from 1,000 BCE, suggest that leprosy has been around for as long as recorded history. But between the 1940s and 1960s, a string of drugs was developed to fight the bacteria, making the disease easy to treat except in areas with poor medical access. Now, it seems, these drugs are beginning to falter.
“This is an important finding,” said Stewart Cole, one of the study’s authors. “The way clofazimine, one of the main leprosy drugs, works is completely unknown but now we have a new lead to investigate thanks to this analysis of multidrug-resistant M. leprae.”
Along with shining light on the present state of leprosy, the study of its genome also revealed its past. Like previous work, the research suggests that leprosy originated in Asia, most likely in the Far East. The team is now trying to build up a bigger picture of the disease's origins and reconstruct its journey throughout the world. Perhaps then, it will be easier to see where it's going.
"For Europe, where leprosy is eradicated, we have to rely on ancient human remains,” added Charlotte Avanzi, one of the researchers. "But it’s possible – we have developed the tools, and now we are ready to sequence even more samples.”