Scientists mapped deer tick, canine tick and lone star tick abundance in Illinois and reported on tick-borne ailments throughout the state from 2018–2022. Credit score: Graphic by Julie McMahon
Scientists analyzed the distribution of three doubtlessly dangerous tick species in Illinois, figuring out areas of the state with greater numbers of those ticks and, due to this fact, at larger danger of an infection with a number of tick-borne ailments.
The examine discovered that, of the three species tracked, the lone star tick, Amblyomma americanum, is most prevalent in southern Illinois; the black-legged tick or deer tick, Ixodes scapularis, is extra widespread in northern and central Illinois; and the canine tick, Dermacentor variabilis, dominates the central and southern components of the state. The findings, reported within the journal Ticks and Tick-borne Ailments, embody clusters of counties with the best variety of ticks of every species.
All three tick species are doubtless current in each Illinois county, mentioned Rebecca Smith, a pathobiology professor on the College of Illinois Urbana-Champaign who led the brand new analysis with graduate scholar Abrar Hussain.
“There are some counties where we’ve looked and we haven’t found them, but most counties that have looked for ticks have found all three species,” Smith mentioned. “It’s just that some ticks are more common in the south, some are more common in the north, and the dog tick does better in central Illinois, where there is a lot of grassland and open habitat.”
Every of those ticks might be contaminated with a number of of a number of pathogens, and a tick chew can cross alongside these infections to people or different animals. Many of those tick-borne ailments undermine human well being and a few, just like the Heartland virus, might be life-threatening.
The lone star tick is a illness vector for ehrlichiosis, tularemia and the Heartland virus, the latter “a condition with low incidence, thankfully, but high mortality,” Smith mentioned. Its chew can also set off Alpha-gal syndrome, an allergy to consuming mammalian meat.
“It’s not a pathogen at all. It’s just a reaction to a sugar molecule present in the saliva of the tick,” Smith mentioned. “The response can be anything from discomfort to anaphylactic shock.”
Canine ticks can transmit ehrlichiosis, Rocky Mountain noticed fever, tularemia and Powassan virus illness, which in uncommon instances causes encephalitis. The deer tick can transmit Lyme illness, anaplasmosis, babesiosis and POWV.
For the brand new examine, the researchers gathered tick-occurrence and tick-borne-disease information from a number of sources, together with the Illinois Division of Public Well being, the Illinois Pure Historical past Survey Insect Assortment, the World Biodiversity Data Facility, a number of museum and academy collections, and iNaturalist, a platform that data citizen-scientist discipline observations. The staff centered on 5 years of recorded observations ending in 2023.
“We knew that tick-borne diseases from the most common, medically important tick species are here in Illinois, so we wanted to see if the hotspots for ticks match with the incidence of diseases transmitted by those ticks,” Hussain mentioned.
Analyzing the information was tough, nonetheless. Solely 80 of 102 Illinois counties collected tick incidence information throughout the examine timeframe, and a few counties had extra aggressive tick-sampling initiatives than others, the researchers mentioned.
Anaplasmosis incidence has remained low throughout the state, with most instances reported in counties missing energetic tick surveillance. Illinois ranks among the many prime 13 states with growing incidences of Alpha-Gal Syndrome. AGS isn’t a reportable situation at current. *Heartland virus was recognized in two people in 2018: one in Kankakee County and one in Williamson County, 272 miles away. A 3rd individual residing in Jackson County was recognized with HV in 2023.. Credit score: Graphic by Julie McMahon
The info included 1,414 ticks collected by means of energetic surveillance in 80 Illinois counties from 2018-2022. The staff constructed spatial statistical fashions to determine county-level clusters with higher-than-expected tick distributions.
The lone star tick was essentially the most prevalent tick species in southern Illinois.
“Ten counties—Union, Johnson, Hardin, Jackson, Williamson, Saline, Franklin, Hamilton, Jefferson and Perry—were identified as spatial clusters” for the lone star tick, they report. “The Illinois Department of Public Health has also classified all ten of these counties as having a high incidence of Ehrlichia chaffeensis,” a pathogen transmitted by this tick. There have been 219 reported human instances of ehrlichiosis in Illinois from 2018–2022.
Illinois additionally “ranks among the top 13 states with increasing incidence of Alpha-gal syndrome,” brought on by the chew of the lone star tick, they wrote.
“With 350 cases, southern Illinois has a high incidence of Rocky Mountain spotted fever group rickettsiosis,” which is transmitted by the canine tick, the staff studies. Pope and Hardin counties in southern Illinois, and Piatt and Moultrie in central Illinois had been recognized as hotspots for the canine tick.
Macon, Piatt, Champaign and Douglas counties in central Illinois, and Prepare dinner, DuPage and Kendall in northeastern Illinois had been recognized as clusters for the deer tick.
Between 2018 and 2022, the state recorded “1,728 cases of Lyme disease, 81 cases of anaplasmosis, and 23 cases of babesiosis,” all of that are transmitted by the deer tick, the researchers report.
Illinoisans who do not stay close to regional hotspots of ticks are nonetheless liable to tick bites from every of those species, Smith mentioned.
“Just because there isn’t a county-level hotspot near you doesn’t mean that there’s no ticks,” she mentioned. “You can have tick hotspots within counties, too. We just don’t have that level of specification for where the ticks are within a county.”
Smith urges folks to guard themselves from ticks each time they enterprise out into wild areas, highway edges, parks, woodlands or prairies. This consists of carrying lengthy pants and light-colored clothes, tucking pants into socks, carrying closed-toed footwear, spraying garments with pesticides and scouring one’s physique for ticks on the finish of a hike. The insecticide permethrin might be utilized to clothes or people can purchase permethrin-treated clothes, she mentioned.
The brand new evaluation gives perception into among the areas which can be most liable to tick-borne illness, Smith mentioned, and can permit well being and security officers to pay attention their sources accordingly. The dearth of information from 22 Illinois counties might undermine these public well being efforts in these components of the state, nonetheless.
Smith can be a professor within the Carl R. Woese Institute for Genomic Biology and the Nationwide Middle for Supercomputing Functions on the U. of I.
Extra info:
Abrar Hussain et al, Spatial distribution and clustering of medically vital tick species in Illinois: Implications for tick-borne illness danger, Ticks and Tick-borne Ailments (2025). DOI: 10.1016/j.ttbdis.2025.102533
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