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Associated Press/Photo by Phil Sandlin

Armored leper

Science | Researchers trace leprosy cases in the U.S. South back to the armadillo

Issue: "After Osama," May 21, 2011

There's a new strain of leprosy on the loose, and if you live in the U.S. South, you just may see it scuttle across the road. Scientists have long suspected the nine-banded armadillo of carrying Hansen's disease-commonly known as leprosy-and transmitting the bacterium to humans. Now researchers have discovered a previously unknown strain of the disease in 28 armadillos and 22 U.S. residents, indicating the conclusive source for about a third of the approximately 150 new human cases of leprosy in the United States each year.

Incidentally, armadillos are native to the Americas, but Hansen's disease is believed to be foreign, brought over by European immigrants centuries ago-so the animals are evening an old score. In armadillos, leprosy attacks internal organs like the liver, but in humans it's concentrated in cooler areas of the body such as hands and feet, where the bacteria can cause a rash, lesions, and in extreme cases permanent nerve damage. With modern antibiotics, the infection is curable but may require one to two years of medication.

Most people actually possess natural immunity to leprosy, and it's difficult to transmit the bacteria through casual contact. Even so, the researchers say people should avoid handling armadillos or hunting them for food (1 in 5 animals may be infected). Their findings appear in the New England Journal of Medicine.

Now they see

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Philosopher John Locke wrote a 17th-century essay arguing that a man born blind, if given sight, would not be able to visually distinguish objects he had previously only recognized by touch. Thinkers have debated the question in the decades since.

Five children from rural India, ages 8 to 17 and blind from birth, have helped provide the best answer so far. The children underwent surgery to restore their sight (by removing cataracts, in four of the cases) and within 48 hours participated in two tests in which they had to match distinctly shaped objects solely by sight or solely by touch. The children scored well. But in a third test, where they tried to identify visually an object they had only previously known by touch, they couldn't reliably pick out the correct object. Locke's hunch, it seems, was mostly right.

However, the children's scores improved quickly. The study, published in Nature Neuroscience, found that within a week two patients were able to pass the touch-to-vision test 80 percent of the time, without any training. The rapid learning suggests that although it takes some experience to integrate new sensory information, the brain is already hardwired for the task.

Mindless navigation

Box jellyfish have-count 'em-24 eyes. Four always point skyward and can see beyond the water surface, according to researchers in Current Biology.

The scientists experimented with Tripedalia cystophora, a small, harmless box jelly species, in its native habitat in Caribbean mangrove swamps. When they moved the jellyfish away from their mangrove shelters (and feeding grounds), the jellies tried to swim for home. But they became disoriented if the mangrove canopy wasn't visible through the water surface above them-proving they sometimes use terrestrial cues to navigate. Pretty smart for an animal without a brain.

Daniel James Devine
Daniel James Devine

Daniel is a reporter for WORLD who covers science, technology, and other topics in the Midwest from his home base in Indiana. Follow Daniel on Twitter @DanJamDevine.

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