Command the children of Israel that they put out of the camp every leper, and every one that hath an issue, and whosoever is unclean by a dead armadillo.
— A horrible misquote of Numbers 5:2

Leprosy, now also called Hansen’s disease, is caused by the bacterium Mycobacterium leprae, a cousin of the bacterium that causes tuberculosis. Leprosy causes a rash and nerve damage that causes skin numbness. Before the age of antibiotics patients were isolated in “leper colonies”. Now the disease is curable.

Before this week all transmission of Hansen’s disease was thought to be from person to person. Armadillos have long been known to carry M leprae also, but it was thought that armadillos and humans had different strains of the bacteria and could not spread leprosy to each other.

A very clever study in this week’s New England Journal of Medicine strongly suggests that humans in the US South are contracting leprosy from armadillos. The study sequenced the DNA of M leprae from a number of patients and armadillos. Patients who likely contracted leprosy abroad, in countries where it has a higher prevalence, had bacteria with strains common in their country of origin. However, patients without foreign travel had a unique M. leprae strain that has not been found elsewhere in the world. This same strain was found in the local armadillos.

This week’s New England Journal of Medicine also has an impressive picture of a rash due to leprosy. (See the link below if interesting rashes float your boat.)

Very few people in the US have leprosy, fewer than four thousand. And you can’t get it by being in the same room as an armadillo. You probably have to be exposed to an armadillo’s blood or eat the uncooked meat. And, again, leprosy is completely treatable. So an encounter with an armadillo is much safer than, say, a bear.

Nevertheless, the media flocked to this story (links to articles below), since who doesn’t want an excuse to publish a picture of a cute armadillo?

So if you accidentally drive over an armadillo, or if you hunt armadillo, don’t handle the carcass without gloves. And if you eat armadillo meat make sure it’s fully cooked. Though I think leprosy or no leprosy, anyone who eats armadillo should be taken out of the camp.

Learn more:

Wall Street Journal article: Leprosy Linked to Armadillos

LA Times article: Armadillos pass leprosy to humans, study finds

New England Journal of Medicine images in clinical medicine: Tuberculoid Leprosy

New England Journal of Medicine article: Probable Zoonotic Leprosy in the Southern United States