Armadillos Give Leprosy to Humans in Southern U.S.: Study

WEDNESDAY April 27, 2011 -- The prehistoric-looking armadillo, already the state animal of Texas, now has a new claim to fame: leprosy.

A new study finds that armadillos carry the bacterium that causes leprosy, and have somehow passed the disease to several dozen humans in the southern United States.

"We've confirmed a long-suspected link between leprosy in humans and armadillos," said the study's lead author, Richard Truman, from the Bureau of Primary Health Care at the Health Resources and Services Administration's National Hansen's Disease Program at Louisiana State University in Baton Rouge.

Truman said it's important to realize that the risk of contracting leprosy (also known as Hansen's disease) from armadillos "is still infinitesimally small."

"The last thing we want is to induce panic in the population and incite a slaughter of armadillos. The best way to combat further infection is through education and prudence," the study's senior author, Stewart Cole, from the Global Health Institute in Lausanne, Switzerland, said in a news release.

James Krahenbuhl, director of the National Hansen's Disease Program, agreed. "This study doesn't change the risk of acquiring Hansen's disease from armadillos. It doesn't increase the risk. In fact, we're hoping publicity should decrease the risk by encouraging the public to decrease their contact with armadillos," he said.

Leprosy, caused by Mycobacterium leprae, is characterized by disfiguring skin lesions and peripheral nerve damage. The disease has been around since Biblical times, and was likely brought to North America by European settlers. People with leprosy were once shunned, and often forced to live in "leper colonies." Fortunately, the disease is treatable today, though it requires a long course of antibiotics.

Krahenbuhl said the treatment consists of a "cocktail" of three antibiotics ideally taken for two years. "The key is to diagnose early to prevent deformity and disability. Once these occur, they're irreversible. And, this is problematic because most physicians aren't even aware that the disease still exists," he said.

Although rare in the United States, leprosy still affects many people in tropical and semitropical areas. Almost 250,000 cases were reported worldwide in 2008. In the United States, the authors estimate that about 150 people develop Hansen's disease each year. And, most of these have traveled to parts of the world where leprosy is more common.

But the researchers noticed that about one-third of new cases developed in people who hadn't left the country, and most of these people lived in Louisiana or Texas.

Since the 1970s, armadillos have been suspected of being potential carriers of the disease. Their low body temperature makes them ideal incubators for the bacteria, according to the authors.

Using DNA analysis, the researchers were able to identify a unique strain of M. leprae that was present in 28 of 33 armadillos tested and 25 of 39 U.S. residents who lived in areas where exposure to armadillos would be possible.

Results of the study are published in the April 28 issue of the New England Journal of Medicine.

"The researchers used the same type of DNA analysis that's used in foodborne illness outbreaks. It's how we know that a certain strain of salmonella is responsible for a particular outbreak," explained Dr. Kenneth Bromberg, director of the Vaccine Research Center at the Brooklyn Hospital Center in New York City.

"This is a warning for people in the south and southwest who might have environmental exposure to stay away from armadillos," said Bromberg.

The study authors recommend that frequent direct contact with armadillos should be discouraged, as should consumption of armadillo meat.

More information

To learn more about leprosy, visit the U.S. Centers for Disease Control and Prevention.

Posted: April 2011


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