Hiding up your nose is a clever strategy for ticks
Thatcher, a young chimp in Uganda’s Kibale National Park, carries a tick species in his nose (one shown, right) that can and does make its way into human nostrils as well.
S.A. Hamer et al/Am. J. Trop. Med Hygiene 2013
Most science press releases aren’t especially fun, either to write or to read, but you know it was a happy day for the press officer at the University of Wisconsin–Madison who wrote “UW Scientist Sniffs Out Possible New Tick Species.” The new tick species, you see, was discovered up the researcher’s nose.
Infectious-disease specialist Tony Goldberg returned from Kibale National Park in western Uganda with the hitchhiker. “When you first realize you have a tick up your nose, it takes a lot of willpower not to claw your face off,” Goldberg said in the press release. Once that impulse passed, he plucked and froze the tick and analyzed its DNA. The resulting sequence didn’t match any known ticks in gene databases and may be a new species, Goldberg and colleagues report September 30 in the American Journal of Tropical Medicine and Hygiene.
“Digging deeper,” the release continues (oh, you kidders), Goldberg narrowed the tick’s identity to the genus Amblyomma, a widespread group of hard ticks known to transmit a number of diseases. He and his colleagues found and photographed ticks in the nostrils of nine of the 45 chimps examined — and those were just the visible ticks. The scientists haven’t conclusively proven that the tick in Goldberg’s nose is the same species as the one in the chimps’ noses, though, because as they note in the paper, “it remains impractical to collect ticks directly from the nostrils of these wild apes.” Indeed, you can’t pick your friends’ noses.
And why the nose? It’s not like ticks have the twisted sense of humor of, say, press officers. Instead, the ticks may have hit upon an excellent way to avoid being groomed away by chimps, which are famous for spending hours bonding as they pick parasites off one another. Chimps do pick their own noses, but it seems possible they could be less adept at getting a deeply lodged tick out of their nostril than they are at grooming elsewhere.
Other parasites have evolved similarly evasive actions: The nose tick paper mentions the chimpanzee louse (Pediculus schaeffi), which freezes when exposed to light (as in the parting of chimp hair) and falls off like a piece of debris. Science News writer Susan Milius mentioned another to me: the gamasine mite, which was found in the 1950s to infect just one ear of its moth hosts, either the right or left. The first mite to dive in just picks either ear, but all the many mites that follow it enter the same ear, sometimes to the point of overflowing. This behavior deafens the moth in just one ear, allowing it to hear well enough to detect an oncoming bat, one of its main predators, and saving the mites themselves from being eaten.
Ugandan nose ticks might pose more of a danger to hosts, since Amblyomma ticks not only carry bacteria that cause diseases such as Q fever and African tick bite fever, but also are likely to require blood from multiple vertebrate hosts to complete their life cycle. That makes the ticks potential transmitters of disease between chimps and humans.
Goldberg was not the first entomologist to find out about Ugandan nose ticks the hard way. In 1961, Science News (then called Science News Letter) reported that visitors to Uganda should watch for “an elusive white tick that may hide in their own noses.” Three entomologists, the story said, discovered ticks in their noses only upon noticing tenderness when they touched or blew their noses. The researcher who found the ticks, G.A. Walton of University College in Cork, Ireland, suggested in Nature that the absence of a reaction to the parasite might mean that the ticks normally infest the noses of a species closely related to humans, specifically chimps. It appears now that he was correct.
People who find a tick in their nose, Science News advised, “are asked to allow the ticks to remain until they are approximately the size of a small pea,” at which point they can be blown out or picked with forceps. Perhaps the readers of 1961 were very patient and calm people who would never claw their faces off upon discovering a nose tick. However, it seems pretty clear why the ticks are able to evade grooming in chimps but have not quite gotten a nosehold in the human population.
