For decades, scientists have theorized that armadillos can pass on leprosy to humans, and they are behind the few dozen cases of the disease that occur in the U.S. each year. Now, they have proof. A genetic study published today in The New England Journal of Medicine indicates that U.S. armadillos and human sufferers share what appears to be a special strain of the bacterium that causes leprosy.
It’s a tricky illness to research: The bacteria grows naturally only in humans and armadillos, and in experiments will grow on the footpads of mice that are genetically engineered.
And in some areas, more than 20 percent of armadillos are infected with leprosy. “It has always been a fascination,” says Richard Truman, a microbiologist at the National Hansen’s Disease Program That’s housed at Louisiana State University at Baton Rouge. Scientists believe their low body temperature gives a fantastic environment for Mycobacterium leprae, the leprosy germs; in humans, also, M. leprae prefers cooler regions, like nostrils, fingers, and feet.
Whether armadillos are connected to human infections in the USA has been”very hard to address,” Truman says. The amount of U.S. instances is minuscule–only 150 people are diagnosed with leprosy annually, and only 30 to 50 of these are believed to have contracted the disease locally. There have been a number of reports of leprosy patients that came into contact with armadillos. John Abide, a dermatologist in Greenville, Mississippi, conducts a solo practice and in recent years has seen three patients with the disorder; further questioning revealed that all three of these were subjected to armadillos. “She might have inhaled fecal material.” And two male patients had murdered armadillos near their homes. Abide printed these case studies in 2008.
To learn more about the home-grown U.S. instances, Truman collaborated with Stewart Cole in the Global Health Institute in the École Polytechnique Fédérale de Lausanne in Switzerland, along with other scientists. They captured wild armadillos in five southern states, conducted whole-genome sequencing of M. leprae found in among these, and compared it to the entire genome of bacteria isolated from the skin of 3 patients. All four strains were basically the same, and, interestingly, didn’t fit leprosy strains reported in different areas of the world, indicating this one was unique to the USA.
Twenty-eight of those critters and 25 of the patients had the new breed. Others harbored previously reported strains the investigators speculate may circulate in a very low level in america.
“I wouldn’t dig in soil which has a great deal of armadillo excrement.” And when an armadillo’s blood”got on my tires of my car by running [the creature ] over, I’d wash it down.” Abide’s patients regained –leprosy is easily treated with a cocktail of three antibiotics–but nevertheless, he says, he recommends steering clear of these animals.