Humans Gave Leprosy to Armadillos. Now, They’re Giving It Back

Wild armadillo meat is popular in Brazil, but a new study shows those who eat it put themselves at risk of contracting leprosy.

By Jason Bittel
Published 30 Jun 2018, 12:18 BST
The majority of nine-banded armadillos (like the one shown here) in Brazil's western state of Pará ...
The majority of nine-banded armadillos (like the one shown here) in Brazil's western state of Pará show signs of exposure to the bacterium that causes leprosy.
Photograph by Joël Sartore, National Geographic Photo Ark

In Brazil, it’s not uncommon to eat armadillo, which reportedly tastes like chicken. But new research warns against the practice—it could give you leprosy.

In a study published n the journal PLOS Neglected Tropical Diseases, researchers found that 62 percent of the nine-banded armadillos sampled in Brazil’s western state of Pará showed signs of exposure to the bacterium that causes leprosy, also known as Hansen’s Disease.

What’s more, the study found that people who eat nine-banded armadillo meat more frequently show higher concentrations of leprosy antibodies in their blood, hinting at a strong correlation between hunting, handling, and eating these animals and contracting the disease.

One dish eaten in certain areas could be particularly problematic: armadillo liver ceviche, a mixture of raw meat and onions. Leprosy-causing bacteria have been shown to concentrate in the liver, as well as the spleen.

The researchers tested 146 local residents and found that 92 of them had antibodies to the leprosy bacteria, suggesting broad exposure.

About 65 percent of people in that part of Brazil eat armadillo at least once per year, says John Spencer, an immunologist at Colorado State University and senior author of the study. “That’s a lot,” he says. “I don’t know if 65 percent of Americans eat lobster once in a year.” (And in all likelihood they don’t, research suggests.)

Reservoir ‘Dillos

Scientists have suspected that armadillos could harbour and transmit the bacterium responsible for leprosy, known as Mycobacterium leprae, since the 1970s. But it wasn’t until 2011 that genetics revealed a match between the strains present in people and armadillos, in places like Texas and Louisiana. This was the smoking gun, so to speak, that the two species were trading the bacteria back and forth. 

Fortunately for people in the southern United States, only around one-fifth of the nine-banded armadillos there seem to carry signs of leprosy. In Pará, the prevalence of leprosy in armadillos is more than three times higher.

So, why are so many of Brazil’s armadillos infected? Probably because Brazilian people have higher rates of leprosy, too, Spencer says.

The U.S. documents around 200 cases of leprosy each year—only around 25 percent of which are associated with armadillos. But Brazil records around 25,000 cases annually, which may actually be an underestimate according to Spencer’s research.

And while it’s true that armadillos can serve as a reservoir for leprosy that can sometimes spill back into humans, it’s worth noting that we gave them the disease first. “People brought leprosy from Europe, with the ships that came from the colonisers,” Spencer says.

“Tastes Like Chicken”

While consuming armadillo meat may strike some as odd, the practice is relatively common in places where armadillos are plentiful and other sources of protein are scarce.

In Portuguese, the nine-banded armadillo is also known as tatu-galinha, or the chicken armadillo, because of the taste of the meat, says Danilo Kluyber, head veterinarian of the Giant Armadillo Conservation Project sponsored by the Naples Zoo.

While nine-banded armadillos are the favourites, some species of naked-tailed armadillos and hairy armadillos are also sought after for their meat. The six-banded ‘dillos are also popular food items because they’ll readily consume anything you feed them, so they can be kept in captivity and fattened up, rather like tiny, armoured pigs.

In so doing, people sometimes handle and even bathe the animals, raising the risk for bacterial transmission, the study notes. But left unperturbed in the wild, the animals pose no danger to people, and in fact play many vital ecological roles like eating insects.

Giant armadillos are more rare and difficult to find, but they are also hunted for food because the animals can weigh as much as a Labrador retriever.

“They can feed a family,” Kluyber says.

The good news is that nine-banded armadillos are plentiful enough to earn a “least concern” status from the IUCN, which assesses endangered species. However, not all armadillo species are so lucky, with several other species native to Brazil making the organisation’s Red List of Threatened Species, including the giant armadillo and the three-banded armadillo. (Related: "How Animal Rescues Like Justin Beaver Help Their Species.")

Big Findings, Small Data

James Loughry, an armadillo expert affiliated with the International Union For Conservation of Nature, called the new paper important “because it demonstrates that the same kind of things are going on in other places aside from the U.S.”

However, he worries that because the researchers were able to analyse only 16 armadillos and 146 humans, the results could be subject to change with broader sampling.

For his part, Spencer says that the Brazilian government gave him and his colleagues permission to sample just 30 armadillos in total. However, the team had to rely on local hunters to share parts of their kill for analysis, something only a handful of them were willing to do—perhaps out of fear of getting into trouble.

This is because it’s actually illegal to hunt any wildlife in Brazil according to federal law.

“But if you’re poor and you need protein in your diet, people do what they need to do,” Spencer says.

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