On a trip five years ago, as he was about to check off the last of all 50 states he’d visited, Daniel Pastula jumped out of the car for a quick photo at the Maine state line. After memorializing the moment, Pastula glanced down to an unwelcome surprise – his pant legs were crawling in ticks.
As Pastula, MD, MHS, brushed the crawling arthropods off his clothing, the irony of the moment greeted him as largely as the state border sign: He was a tick expert and educator, a doctor who treated patients with tick-borne diseases. Yet he had just stood in the tall grass of Maine – in May.
Daniel Pastula, MD, celebrates entry into his 50th state in May of 2018, oblivious to the 10-plus ticks crawling up his legs.
Maine harbors ticks and routinely ranks as a top state for recorded Lyme disease cases. Grassy areas serve as prime habitat, where ticks sit in wait for the next warm-blooded body that comes near. And May is generally peak tick season, including in Colorado.
“I was like: I literally do this for a living, and I’ve got 10 to 20 ticks on me,” Pastula, an associate professor of epidemiology, neurology and infectious diseases at the Colorado School of Public Health and the University of Colorado School of Medicine.
In Colorado, recent months of soggy weather could spell a long season ahead, which typically fades during hotter summer months and undergoes another surge, though generally smaller, in the fall. And it appears to be off to an active start.
May: awareness month for a reason
“Everyone is saying that this year is a bad tick year in Colorado,” said Daniel Salkeld, PhD, an instructor in the ColoradoSPH Department of Environmental & Occupational Health, who also studies ticks. “That would make sense with the long, wet winter,” he said, noting that holed-up people might be hitting the outdoors more and encountering ticks as well.
May is also Lyme disease awareness month for a reason, Salkeld said of the most widely known tick-borne disease not endemic in Colorado. “We ran a citizen science project where people could submit ticks for pathogen testing, and May was our bumper month for submissions from all corners of the U.S.”
Ticks are “literally blood-sucking parasites” in the arachnid class with spiders, Pastula said. They feed on mammals, birds, reptiles, humans, or basically any land-based creature with blood, he said. They are an ancient organism, evolving since long before primates and humans emerged.
With nearly 30 species in Colorado alone, many different tick types carrying a huge array of bacteria, viruses and other pathogens quietly crawl around the country, although most heavily in the coastal regions.
A tick migration: Head west, young nymph
“They generally prefer warmth and humidity,” Pastula said, noting one potential factor at play in a widening range and extended U.S. tick season as the Earth’s temperatures warm.
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Recent maps show Lyme disease and the ticks it most commonly rides in on (blacklegged ticks) marching ever-farther west from its East Coast states. Whether the disease – which, if not treated early, can cause life-long debilitating symptoms – could get to Colorado is hard to predict, Pastula said.
“All of these vector-borne diseases really depend on a complex interplay of factors,” including tick, animal, human and climate behavior, he said. “Our climate, both temperature and precipitation, are not favorable for the ecologic cycle responsible for Lyme disease,” Pastula said.
“Could animal migration, human migration or climate change alter where Lyme disease is endemic? It’s entirely possible. But right now, there’s no evidence that it’s here in Colorado. The farthest known it gets is around the western Great Lakes region and the western Midwest.”
Know the risk, at home and away
There are many other tick-borne diseases that can be just as dangerous, including Colorado’s top four: Rocky Mountain spotted fever, tularemia, tick-borne relapsing fever and Colorado tick fever (the most common), Pastula said.
Despite its name, Rocky Mountain spotted fever is rarer in Colorado than some other places. “You see this more in the Southwestern and Mexico and in the Southeast and South Central regions of the United States.”
For doctors, diagnosis relies largely on history, Pastula said. In most people, tick-borne diseases will become symptomatic during spring through fall. You may see fevers (some of which may be “relapsing” where fevers get better for a while and return) and rash. “We can see relapsing fever with Colorado tick fever,” he said.
Tick surveillance and awareness is crucial for healthcare providers and the general public, especially for travelers as we enter vacation season, Salkeld said.
“If you're heading out-of-state, remember that ticks can be an issue in almost any state. And there might be pathogens that are transmitted, like Lyme disease, that are not necessarily on a Colorado doctor's radar.
“So, if you get bitten, remind your doctor. Or, if you come back from a trip and start to feel ill – flu-like symptoms, aches, fever – then make sure to keep tick-borne disease in mind. You might have been bitten by a nymph (younger and smaller tick) and never noticed.”
Pinpointing tick disease
Blood work may show low platelet (thrombocytopenia) or low white blood cell (leukopenia) counts with many tick-borne diseases.
Some tests are commercial, such as with Lyme disease, but others are not, so doctors and anyone concerned about a tick-borne disease should work with local and/or state public health agencies, Pastula said.
“At the Colorado Department of Public Health and Environment, there is a vector-borne disease coordinator that can help with questions and testing coordination. Many other states also have such coordinators. Sometimes state labs can test; sometimes they send it to the CDC.”
For bacterial diseases, such as Rocky Mountain spotted fever and tularemia, doctors have antibiotics for treatment. Viral diseases, such as Colorado tick fever, can be treated only symptomatically.
Although it’s believed that Lyme disease takes hours to transmit after the tick has attached, some viruses can transmit in as quickly as 15 minutes, Pastula said. The onset of symptoms for tick-borne diseases can range from days to as long as four weeks.
Prevention: It’s the best medicine
Obviously, prevention is best. Staying on trails and avoiding brushy areas helps prevent ticks, who often attach after climbing to the end of vegetation. Called “questing,” the tick hooks its back legs onto the blade or leaf and holds its front arms out as if awaiting a hug.
“They will hold like this for hours, waiting for the next unsuspecting deer, rodent, or reader of your article to walk by, and then they will latch on,” Pastula said.
Once they climb aboard, they crawl around looking for a safe space before they attach, he said. “They look for warm, out-of-the-way places,” Pastula said, like armpits, hair lines, between toes, behind ears or under tight clothes bands.
The take-home, he said, is that you often have time to knock them off before they attach, so when you are outdoors, periodically check for ticks.
Salkeld agreed, adding that people should always do tick checks before they get into their car or go into their home or tent. Once inside the home, put all clothes in a hot dryer for at least 10 minutes, do a thorough tick check and shower, he said.
“I think the overwhelming message is tick-borne diseases are largely preventable,” Pastula said. “From surveys, we know most people aren’t taking, possibly because they are unaware, prevention measures. Ticks are potentially dangerous. There are things you can do to reduce the risk from them.”