Science  29 Apr 2011:
Vol. 332, Issue 6029, pp. 519

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  1. Don't Pet That Armadillo

    Armadillos are familiar creatures in the American southwest, where they haunt gardens and roadsides. But scientists have long eyed the animals with distrust, considering them suspect number one in transmitting leprosy to people in the United States. Now, that suspicion seems justified.

    This week, a team of top leprosy experts reports in The New England Journal of Medicine that they've found a particular strain of Mycobacterium leprae, which causes the skin and nerve disease, in a wild armadillo and three U.S. patients. Genetic sequencing revealed that it is a new strain that appears to be indigenous to the United States—it hasn't been described anywhere else in the world. Further testing uncovered the same strain in 28 of 33 wild armadillos and 25 of 39 U.S. leprosy patients. The authors speculate that armadillos pass the bacteria efficiently to one another.

    “All of a sudden it's everywhere,” says John Abide, a dermatologist in rural Greenville, Michigan, who just 2 weeks ago came across his fourth suspected case of leprosy, in an older man. Armadillos might be cute, he says, “but you just got to stay away from them.”

  2. Central U.S. Quake Threat Real


    Two hundred years ago this December, a series of three large earthquakes centered in southeastern Missouri destroyed the little town of New Madrid and rattled the entire eastern half of the country. Four similar quake clusters have struck the same area over the past few thousand years. But some seismologists have said the risk of another damaging New Madrid quake is now past.

    Don't believe it, says an eight-member expert panel convened by the National Earthquake Prediction Evaluation Council. In its new report, the panel concludes that while it's conceivable that the New Madrid threat is past, “we and most other experts consider this claim unlikely.”

    But forecasting quakes in this area is difficult, largely because scientists don't understand the drivers. The motions of tectonic plates, which cause quakes around the Pacific and at other plate edges, don't explain quakes in the interiors of continents. And there are precious few geophysical signs that New Madrid could be building toward another large quake. Given all the uncertainty, says the panel's chair, seismologist John Vidale of the University of Washington, Seattle, “the prudent thing to do is assume earthquakes will continue.”

  3. Spreading Disease-Proof Mosquitoes

    Suppose you have designed a mosquito that can't transmit malaria or another major scourge. Now what? If you release the critters, they will be vastly outnumbered by the billions of natural mosquitoes already out there. Now, scientists have developed a genetic trick that could help disease-resistant mosquitoes spread like wildfire.

    A team led by molecular biologists Andrea Crisanti and Austin Burt of Imperial College London reported online in Nature last week the development of a so-called gene drive system. It uses a homing-endonuclease gene (HEG), which creates a second copy of itself in individuals that have only one, ensuring that all offspring have the gene.

    The researchers bred a population of Anopheles gambiae mosquitoes that glow in the dark, thanks to a gene that produces green fluorescent protein (GFP). Then they released into the insects' cages small numbers of mosquitoes with a HEG that breaks up the GFP gene in sperm cells and swaps itself in on the chromosome. Over generations, fewer mosquitoes were glowing, indicating that the gene spread rapidly. The next step, Crisanti says, is to make HEG break up a mosquito gene crucial for malaria transmission.