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Brain Food: Soft Ticks and Relapsing Fever


Soft ticks are arachnids, like spiders. They live in pine and hardwood forests and thrive on the blood of mice, squirrels, chipmunks and sometimes birds. They don’t usually feed on humans, but, as in the case that closed Camp Colton near Flagstaff recently, it does happen once in awhile. Northern Arizona University Forest Entomology Professor Rich Hofstetter explains.

“For the ticks to move onto humans, which is not their main host, usually the rodent nest would have to be disturbed, or maybe even sprayed with pesticide could cause them to move. And so, if someone is trying to clean out their garage or their attic and move rodent bedding or material it’s going to cause these ticks to disperse,” Hofstetter says.

Credit Courtesy photo
Northern Arizona University entomologist Rich Hofstetter.

Soft ticks can carry bacteria that make humans sick. The disease is called tick-born relapsing fever. Besides the fever that lasts a few days, disappears and then comes back, the illness can also cause nausea, diarrhea and dizziness. Hofstetter says symptoms may not show up for a week or so.

“What’s interesting with the soft ticks is that they feed very quickly and don’t leave any trace. So they feed within 15 or 20 minutes. While hard ticks will stay on your body for a day or two, and they’re very obvious, they swell up and you see the tick on your body,” Hofstetter says.

Hofstetter says the bacteria carried by soft ticks is similar to the organism that causes Lyme disease. That’s transmitted by hard ticks, the kind found on dogs and deer. He says the relapsing fever is not nearly as dangerous and is easily treated with antibiotics.

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