For students, faculty members and residents, Charlottesville’s sunny summer days may offer the ideal opportunity to explore local trails or hike through Shenandoah National Park. But without proper precautions, bacterial infections acquired through tick bites can pose a serious health threat to those who spend time in woody or brushy areas.
So far this year, the Elson Student Health Center has treated 10 cases of tick-borne illnesses or concern for tick-borne illnesses. In the previous two years, Student Health physicians saw a total of 50 tick cases.
David Gaines, state public health entomologist at the Virginia Department of Health, explained that ticks are mainly acquired in shady forest areas and are not common in hot, sunny fields. These forest ticks are attracted to “carbon dioxide, body heat, some body odors and … movement.”
Gaines also said that it’s a myth that ticks climb trees and occupy high levels of vegetation. Instead, they are most likely to be found at sock level.
“When [ticks] see motion, or feel movement / vibration of the ground, or on the vegetation or leaf-litter they are sitting on, they wave their front legs in the air, hoping to attach onto whatever it is that is passing by,” Gaines said.
Gaines and Student Health recommend the prevention of ticks by dressing appropriately with long-sleeved clothing and applying adequate repellant before venturing into the woods. Because ticks are more likely to be found along the forest floor, DEET-containing insect repellents — which are safe to use on the skin — should be applied around the ankles and lower legs.
Additionally, Gaines recommends tucking pants into socks, and Student Health encourages the treatment of pants, shoes and tents with 0.5 percent permethrin, an insecticide that kills ticks but cannot be applied directly to the skin.
For those embarking on a long trail hike spanning several days, William Petri, physician and professor of infectious diseases and international health at the School of Medicine, recommends checking for ticks every day, especially near the groin, armpits, scalp and behind the knees.
Petri explained that there are three main tick-borne diseases in central Virginia — Lyme disease, ehrlichiosis and Rocky Mountain spotted fever.
“The tick has to be attached for 24 hours in order to transmit Lyme disease, Rocky Mountain spotted fever or ehrlichiosis,” Petri said. “If you’ve removed them, you’ve removed any risk of a tick-borne infection.”
The Centers for Disease Control and Prevention provide an online guide for removing ticks with tweezers. After removal, the skin affected by the tick should be cleaned with soap and water. Showering within two hours of returning indoors can reduce the risk of tick-borne diseases.
For those hiking with a furry friend, pets may carry a risk for tick-borne illnesses.
“If you have a pet, treating them with monthly tick prevention medication can also reduce the risk that they can carry ticks that may transfer to humans,” Student Health physician Neil Silva said in an email. “A vet can also check them for ticks.”
The most common tick-borne disease is Lyme disease, which is caused by spiral-shaped bacteria carried by ticks that feed on mice or other mammals.
The majority of people with Lyme disease have a characteristic ring-shaped rash — erythema migrans — in addition to flu-like symptoms. Unlike the flu, which typically lasts from November to March, Lyme disease peaks around July or August and concludes in October.
Those with later stages of Lyme disease may develop “relapsing and remitting arthritis of the knee” in addition to an irregular heartbeat, according to Petri.
Gaines explained that children and teens between the ages of 5 to 15 are most susceptible to Lyme disease while those between the ages of 20 to 30 are least susceptible, with disease risk increasing after crossing this age range.
The black-legged or deer tick that carries Lyme disease is predominant in areas with an elevation above 1700 feet. They prefer cool, humid environments and cannot survive in the hottest parts of Virginia.
In terms of prevalence of tick-borne illnesses, Petri said that RMSF and ehrlichiosis are likely tied for second place. However, Gaines adds that while the Virginia Department of Health has had over 2,500 RMSF cases reported by doctors across Virginia, the vast majority of those cases were questionable due to inaccurate serological test results that are used to support RMSF diagnoses.
RMSF, like Lyme disease, is accompanied by flu-like symptoms in addition to a characteristic spotted rash. This rash is caused by the RMSF bacteria inflaming the endothelial cells that line blood vessels and appears three to seven days following infection. Petri recommends not waiting until after the rash appears to seek medical help.
“It’s really important as a patient that you tell the physician that you pulled a tick off … because that makes the physician think about the diagnosis since there’s no test for Rocky Mountain spotted fever that the lab can do,” Petri said.
Ehrlichiosis is nearly the same as RMSF, except it does not have a characteristic rash. Instead, ehrlichiosis bacteria replicate inside white blood cells and can be detected with a blood smear test.
Lone star ticks, which have a white spot on the back, carry ehrlichiosis and are common in hot, dry weather below 1700 feet. Research led by Thomas Platts-Mills, physician and professor of allergy and clinical immunology, connected lone star tick bites to red meat allergies that are accompanied by hives and anaphylaxis several hours after red meat consumption.
With the exception of the red meat allergy, all three of tick-borne diseases are treated by the same antibiotic called doxycycline, which does not have antibiotic resistance. Furthermore, Student Health regularly offers treatment for tick-borne diseases.
“We first talk to a patient to obtain a history and do an examination,” Silva said. “If there is risk for a possible exposure or disease, … we would come to a recommendation for care for the particular type of tick-borne illness we were concerned about.”
Readers interested in learning more about checking for tick-borne disease symptoms or the geographic distribution of ticks can visit the CDC.
Correction: This article previously stated that ticks “jump” when they sense motion. The article has since been revised to state that upon detecting motion, ticks raise their legs and wait to attach to the source of motion. Additionally, RMSF may be overreported by doctors as stated by Gaines after the article was published.