Two Rare Little Bats Linked to U.S. Rabies Transmittal

Most U.S. human rabies cases in recent years have been tracked to two unusual species of bats that, oddly enough, rarely have rabies.

Scientists have theories--but no clear answers--about why this is. “We didn’t ask for this mystery,� says Charles E. Rupprecht, rabies chief at the Centers for Disease Control and Prevention in Atlanta.

About three-quarters of the bat-borne rabies cases over the last two decades have been traced to the silver-haired bat and the Eastern pipistrelle.

The Eastern pipistrelle is one of the smallest bats, about three inches long when curled up, with brownish-gold fur. The silver-haired is a little bigger, black with silver highlights.

The silver-haired is a solitary animal that lives mostly under the bark of trees, while the pipistrelle is less reclusive. It is sometimes found living around people in basements and such, but it does not form large colonies like the big brown bat, the most common species.

Some experts theorize that these two kinds of bats might be more aggressive than others. And because their teeth are especially small, people might be less likely to recognize their bites. Moreover, scientists believe that rabies virus from these bats may be especially adept at reproducing in the victim’s skin before invading the nervous system.