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Storied “monster” is just a furry victim of mites

Oct. 22, 2010
Courtesy of the University of Michigan
and World Science staff

As Hal­low­een ap­proaches, ta­les of mon­sters and creepy crawlies abound. Among the more in­sid­i­ous is a leg­end­ary beast known as the chu­pa­ca­bras.

But this supposedly fanged, hair­less an­i­mal said to at­tack and drink the blood of live­stock is not the real fiend, sci­en­tists say. In­stead, it’s a ti­ny, eight-legged mite that turns a healthy, wild an­i­mal in­to a chu­pa­ca­bras, says Uni­vers­ity of Mich­i­gan bi­ol­o­gist Bar­ry OCon­nor.

Sci­en­tists be­lieve leg­end­ary chu­pacabras mon­sters are ac­tu­al­ly coy­otes with se­vere cases of mange, like the an­i­mal above. (Cred­it: Dan Pence)


The ex­ist­ence of the chu­pa­ca­bras, al­so known as the goat­suck­er, was first sur­mised from live­stock at­tacks in Puerto Rico, where dead sheep were dis­cov­ered with punc­ture wounds, to­tally drained of blood.

Si­m­i­lar re­ports be­gan ac­cu­mu­lating from oth­er places in Lat­in Amer­i­ca and the U.S. Then came sight­ings of evil-look­ing an­i­mals, var­i­ously de­scribed as dog-like, ro­d­ent-like or rep­tile-like, with long snouts, large fangs, leath­ery or sca­ly green­ish-gray skin and a nas­ty odor. 

Lo­cals put two and two to­geth­er and as­sumed the ugly varmints were re­spon­si­ble for the kill­ings.

But sci­en­tists have now stud­ied some of the chu­pa­ca­bras car­casses and con­clud­ed that the dreaded mon­sters ac­tu­ally were coy­otes with ex­treme cases of mange—a skin con­di­tion caused by mites bur­row­ing un­der the skin. OCon­nor, who stud­ies the mites that cause mange, con­curs and has an idea why the ti­ny as­sailants af­fect wild coy­otes so se­vere­ly, turn­ing them in­to atro­ci­ties.

OCon­nor said the mite re­spon­si­ble for the ex­treme hair loss seen in “chu­pa­ca­bras syn­drome” is Sar­coptes sca­biei, which al­so causes the itchy rash known as sca­bies in peo­ple. Hu­man sca­bies is an an­noy­ance, but not usu­ally a se­ri­ous health or ap­pear­ance prob­lem, partly be­cause our bod­ies are al­ready vir­tu­ally hair­less and partly be­cause the popula­t­ion of mites on a giv­en per­son usu­ally is rel­a­tively smal­l­—only 20 or 30 mites.

Ev­o­lu­tion­ary stud­ies done by OCon­nor and his form­er grad­u­ate stu­dent Hans Klom­pen, now an as­so­ci­ate pro­fes­sor at Ohio State Uni­vers­ity, sug­gest that the sca­bies mite has been with us through­out our ev­o­lu­tion­ary his­to­ry, giv­ing hu­mans plen­ty of time to de­vel­op de­fenses. When hu­mans be­gan do­mes­ti­cat­ing an­i­mals, Sar­coptes sca­biei found a whole new realm of po­ten­tial vic­tims. Do­mes­tic dogs, like hu­mans, have played host to the mites long enough to evolve the abil­ity to fight off mange, but when the con­di­tion spreads to wild mem­bers of the dog fam­i­ly—foxes, wolves and coy­otes—watch out.

“When­ever you have a new host-par­a­site as­socia­t­ion, it’s pret­ty nas­ty,” said OCon­nor. “It does a lot of dam­age, and mor­tal­ity can be rel­a­tively high be­cause that host spe­cies has not had any ev­o­lu­tion­ary his­to­ry with the par­a­site, so it has not been able to evolve any de­fenses like we have.”

In these un­lucky an­i­mals, hordes of mites bur­row­ing un­der the skin cause in­flamma­t­ion and skin thick­en­ing. Blood supply to hair fol­li­cles is cut off, so the fur falls out. In se­vere cases, the an­i­mal’s weak­ened con­di­tion opens the door to bac­te­ria that cause sec­ond­ary skin in­fec­tions, some­times pro­duc­ing a foul odor. Put it all to­geth­er, and you’ve got an ug­ly, na­ked, leath­ery, smelly mon­stros­ity: the chu­pa­ca­bras.

Do mite in­festa­t­ions al­so change the an­i­mals’ be­hav­ior, turn­ing them in­to blood­thirsty killers? Not ne­ces­sarily: there are other pos­sible ex­plan­a­t­ions for why they seem more likely to prey on small live­stock such as sheep and goats, OCon­nor said. “Be­cause these an­i­mals are greatly weak­ened, they’re go­ing to have a hard time hunt­ing... so they may be forced in­to at­tacking live­stock be­cause it’s eas­i­er than run­ning down a rab­bit or a deer.”

While the chu­pa­ca­bras has achieved leg­end­ary sta­tus, oth­er wild an­i­mals can suf­fer just as much from the ef­fects of mange mites, OCon­nor said. In Aus­tral­ia, the mite is kill­ing off wom­bats. “They pre­sumably got the mites from din­goes, which got them from do­mes­tic dogs, which got them from us,” he said.

And a re­lat­ed mite, just as in­sid­i­ous, can drive squir­rels to self-destruct. In his grad­u­ate school years at Cor­nell Uni­vers­ity, OCon­nor ob­served mange-weak­ened squir­rels fall­ing from trees. That ob­serva­t­ion led him to con­duct an in­for­mal sur­vey to see if man­gy squir­rels al­so were more likely than healthy squir­rels to end up as road kill. They were, he said, sug­gesting that be­ing tor­mented by mites made the squir­rels less ad­ept at dodg­ing cars.


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As Halloween approaches, tales of monsters and creepy crawlies abound. Among the more insidious is a legendary beast known as the chupacabras. But the real fiend isn’t the hairless, fanged animal purported to attack and drink the blood of livestock, scientists say. Instead, it’s a tiny, eight-legged mite that turns a healthy, wild animal into a chupacabras, said University of Michigan biologist Barry OConnor. The existence of the chupacabras, also known as the goatsucker, was first surmised from livestock attacks in Puerto Rico, where dead sheep were discovered with puncture wounds, completely drained of blood. Similar reports began accumulating from other locations in Latin America and the U.S. Then came sightings of evil-looking animals, variously described as dog-like, rodent-like or reptile-like, with long snouts, large fangs, leathery or scaly greenish-gray skin and a nasty odor. Locals put two and two together and assumed the ugly varmints were responsible for the killings. Scientists studied some of the chupacabras carcasses and concluded that the dreaded monsters actually were coyotes with extreme cases of mange—a skin condition caused by mites burrowing under the skin. OConnor, who studies the mites that cause mange, concurs and has an idea why the tiny assailants affect wild coyotes so severely, turning them into atrocities. OConnor said the mite responsible for the extreme hair loss seen in “chupacabras syndrome” is Sarcoptes scabiei, which also causes the itchy rash known as scabies in people. Human scabies is an annoyance, but not usually a serious health or appearance problem, partly because our bodies are already virtually hairless and partly because the population of mites on a given person usually is relatively small—only 20 or 30 mites. Evolutionary studies done by OConnor and his former graduate student Hans Klompen, now an associate professor at Ohio State University, suggest that the scabies mite has been with us throughout our evolutionary history, giving humans plenty of time to develop defenses. When humans began domesticating animals, Sarcoptes scabiei found a whole new realm of potential victims. Domestic dogs, like humans, have played host to the mites long enough to evolve the ability to fight off mange, but when the condition spreads to wild members of the dog family—foxes, wolves and coyotes—watch out. “Whenever you have a new host-parasite association, it’s pretty nasty,” said OConnor. “It does a lot of damage, and mortality can be relatively high because that host species has not had any evolutionary history with the parasite, so it has not been able to evolve any defenses like we have.” In these unlucky animals, hordes of mites burrowing under the skin cause inflammation and skin thickening. Blood supply to hair follicles is cut off, so the fur falls out. In severe cases, the animal’s weakened condition opens the door to bacteria that cause secondary skin infections, sometimes producing a foul odor. Put it all together, and you’ve got an ugly, naked, leathery, smelly monstrosity: the chupacabras. Do mite infestations also alter the animals’ behavior, turning them into bloodthirsty killers? Not exactly, but there may be an explanation for why they may be particularly likely to prey on small livestock such as sheep and goats. “Because these animals are greatly weakened, they’re going to have a hard time hunting,” OConnor said. “So they may be forced into attacking livestock because it’s easier than running down a rabbit or a deer.” While the chupacabras has achieved legendary status, other wild animals can suffer just as much from the effects of mange mites, OConnor said. In Australia, the mite is killing off wombats. “They presumably got the mites from dingoes, which got them from domestic dogs, which got them from us,” he said. And a related mite, just as insidious, can drive squirrels to self-destruct. In his graduate school years at Cornell University, OConnor observed mange-weakened squirrels falling from trees. That observation led him to conduct an informal survey to see if mangy squirrels also were more likely than healthy squirrels to end up as road kill. They were, suggesting that being tormented by mites made the squirrels less adept at dodging cars.