Studying ticks: RML researchers collect insects to document disease prevalence
Rocky Mountain Laboratory staff scientist Brandi Williamson collects a wood tick at the Blodgett Creek trailhead last week.
Sometimes it seems that the more things change, the more they stay the same.
In the scientific world of wood tick collection on the hillsides surrounding the Bitterroot Valley, not much has changed over the decades.
Last week, Rocky Mountain Laboratory scientists fanned out around the Blodgett Creek trailhead in search of ticks for an ongoing study documenting the prevalence of Colorado tick fever in the Bitterroot.
The crews didn’t bring along modern high-tech equipment to help with their quest to capture the arachnids.
Instead, they resorted to the same age-old technique employed by generations of RML scientists in their tick-gathering quests. Armed with something akin to a broomstick topped with a large white flag, the four-person crew working under the lead of RML staff scientist Brandi Williamson waved their banners over the top of new grass and shrubs.
Waiting there were the tiny eight-legged insects. Each leg tipped with a tiny grappling-like hook, the ticks grabbed hold of the flag as it fluttered by.
With tweezers and a steady hand, the scientists carefully collected the ticks in vials that would keep them safe until Williamson could get them back to the laboratory, freeze them solid and then smash them into a paste.
From there, she would employ techniques to search for the molecular structure of the virus that causes Colorado tick fever in humans.
Williamson began her project in 2009. Up until this year, most of the ticks that she’s studied have been supplied by U.S. Forest Service workers or RML scientists who happened to discover the ticks while they were outdoors for either work or play.
Her project follows in the footsteps of well-known RML scientists Willy Burgdorfer and Carl Eklund, who did a similar study in the 1960s. Back then, the pair didn’t have access to the highly technical equipment now found at the lab and used animals to test for the prevalence of the virus.
Their findings nearly mirror the preliminary results that Williamson has gathered thus far.
In the areas tested in the 1960s, the RML scientists found that up to 16 percent of the ticks they captured carried the virus. In some areas, they couldn’t find the virus at all.
Of the 800 ticks that Williamson has tested so far from both the east and west sides of the Bitterroot Valley, an average of 6 percent of ticks carry the virus. So far the hot spot is around Blodgett, where 19 percent of the 78 ticks she collected were carriers.
“The virus is widespread,” said RML’s Tom Schwan. “People should be aware that ticks are carrying micro-organisms that can be passed on to them. The best way to prevent ticks from passing on the virus is to not let them feed on you in the first place.”
Williamson said the best way to remove a tick is with a pair of tweezers. Gently grab hold of the tick as close to the skin as possible and pull upward slowly until it releases.
“You want to make sure that there are no mouth parts left in the bite,” she said. “Those can become infected.”
Colorado tick fever is an acute viral infection that’s spread by the bite of the type of wood tick common to the Bitterroot.
That same type of tick also carries the more virulent Rocky Mountain spotted fever. In the Bitterroot Valley, about 1 percent of ticks carry that disease.
Symptoms of Colorado tick fever most often begin three to six days after a tick bite. It typically starts with a sudden fever that continues for three days and then comes back for a few more days after a one- to three-day break.
Other symptoms include general weakness, headache behind the eyes, muscle aches, as well as nausea and vomiting.
“It’s not highly lethal,” Schwan said. “There’s no treatment for it.”
The virus was first detected in the 1940s in Colorado. It’s been documented from southern British Columbia down through most of the western states.
While Colorado tick fever has no treatment, Rocky Mountain spotted fever does. It’s important for people to see a physician as soon as possible if they begin feeling ill or see a rash form following a tick bite.
Rocky Mountain Laboratories no longer tests ticks for disease.
Schwan said it’s been a long time since it has done that for people. Since it takes time to find a laboratory that does that kind of testing and even more time to get the tests completed, Schwan said it’s probably a good idea to skip that step.
“If everything points in the direction that people might be infected, they should seek medical attention,” he said. “People die every year from spotted fever. The key is being diagnosed in time to be treated with the right antibiotics.”
Williamson plans to complete her study this year.
“It’s already shown us that this virus is still out there,” she said. “And that’s a very good reason to not let ticks feed on you.”
Reach reporter Perry Backus at 363-3300 or pbackus@ravallirepublic.com.
