79
per square mile
Estimated human
population density of
Walker County, Texas
256
per square mile
Estimated armadillo
population density of
Walker County, Texas
Armadillos may transmit leprosy
Same strain shows up in patients and animals in Deep South
By Nathan Seppa
People infected with leprosy in the
United States often have the same previously unknown strain of the microbe
Mycobacterium leprae that is also carried
by armadillos. Though it has been known
for decades that armadillos can harbor
leprosy, also called Hansen’s disease,
the discovery of the overlapping strain
strengthens the long-held assumption
that armadillos can infect people directly.
Researchers report in the April 28
New England Journal of Medicine that
many infected people in the Deep South
contracted leprosy while close to home,
not in some exotic locale where the disease is more common. The only possible
infectious agents would be a person or an
armadillo, the only other animal known
to harbor leprosy. Some of the infected
people had even handled armadillos.
The findings all point to animal-to-per-
son spread. “It’s still not a smoking gun,
but it’s getting awfully close,” says James
Loughry, a zoologist and armadillo expert
at Valdosta State University in Georgia
who wasn’t involved in this research. “It’s
hard to imagine that it’s not being trans-
mitted from armadillos to humans.”
Richard Truman, a microbiologist
at the National Hansen’s Disease Pro-
gram and Louisiana State University in
Baton Rouge, and his colleagues com-
pared bacterial samples from 50 patients
in Louisiana and from 33 infected wild
armadillos from five Southern states.
A highly specific strain of the bacte-
rium showed up in 28 of the 33 animals
and in 22 of 29 patients who had never
lived outside the United States and
Mexico. Interviews with 15 of the leprosy
patients further revealed that eight had
had direct contact with armadillos.
Loughry says 6 to 10 percent of armadillos he has tested in Mississippi and
Alabama have leprosy. Other studies put
Armadillos with leprosy harbor a rare
bacterial strain that also infects people.
the rate as high as 20 percent in the wild.
The nine-banded armadillo is the only
armadillo found in the United States.
There are many kinds of armadillos in
Latin America, but it is not known if the
other types contract leprosy.
Half-asleep rats
look wide awake
Parts of brain can doze off
even in an active animal
By Tina Hesman Saey
Some parts of a rat’s brain can fall asleep
even while the animal seems fully awake.
Researchers at the University of Wisconsin–Madison and colleagues in Italy
kept rats up four hours later than usual.
Even though the rats stayed awake, electrodes implanted in their brains showed
that some brain cells went to sleep while
neighboring ones remained active, the
team reports in the April 28 Nature.
The rats were also prone to making
mistakes during slightly difficult tasks,
a finding that may have implications for
sleep-deprived people.
As far as neuroscientist Giulio Tononi
and his team could tell, the rats were
fully awake and playing with objects
that the team had supplied to keep the
animals up past their bedtimes. Only
electrodes implanted in two parts of
the brain recorded the neuron naps.
www.sciencenews.org
May 21, 2011 | SCIENCE NEWS | 9
