Ticks and tickborne diseases in the upper Midwestern United States: role for citizen science in assessing exposure risk

This study utilized a citizen science program in the upper Midwestern United States to map tick ranges and found that while *Amblyomma americanum* has not yet established in the region, adult *Ixodes scapularis* ticks exhibit high prevalence of multiple pathogens, including *Borrelia burgdorferi*, providing critical data for assessing local tickborne disease risks.

The Gist

Imagine the upper Midwest of the United States as a vast, quiet neighborhood where a specific kind of tiny, eight-legged hitchhiker—ticks—lives. For years, people have worried about the most famous hitchhiker, the Ixodes scapularis tick, which carries Lyme disease. But there's also a growing worry about a different hitchhiker, the Amblyomma americanum (or Lone Star tick), which has been slowly packing its bags and moving north, like a family trying to find a new home in a cooler climate.

To get a real sense of who is moving in and what they might be carrying, researchers launched a "neighborhood watch" program in 2024. Instead of hiring a team of scientists to hunt for ticks in the woods, they asked regular people to be the eyes and ears. This is citizen science: if you found a tick on your dog, yourself, or your clothes, you sent it to the lab.

The Big Catch
In just the first two years, this neighborhood watch collected a massive haul: over 12,000 ticks, mostly from Wisconsin. It's like having a giant jar filled with thousands of tiny, mysterious packages that people dropped off at the door.

The Newcomers
When the scientists looked at the Lone Star ticks (Amblyomma americanum) that people sent in, they found them outside their usual southern territory. However, the paper notes that while these "visitors" showed up, there was no proof yet that they had actually moved in to stay and build a permanent colony in the study area. They were just passing through or exploring, not yet setting up a permanent residence.

The Cargo Check
The real detective work happened with the Lyme-carrying ticks (Ixodes scapularis). The scientists acted like customs officers, opening up 707 of the adult female ticks to see what "cargo" (germs) they were hiding inside. Here is what they found:

• Lyme Disease (Borrelia burgdorferi): This was the most common stowaway, found in 51% of the ticks checked. It's like finding that half the packages in the jar contained this specific item.
• Babesia and Anaplasma: These were found in about 9% of the ticks each.
• Ehrlichia: A rarer find, appearing in 3% of the ticks.

The "Double Trouble" Factor
Sometimes, a single tick wasn't just carrying one germ; it was carrying a whole set. In 14% of the ticks, the scientists found multiple pathogens at once. They also noticed that certain germs seemed to travel together more often than others, like friends who always show up at the same party. For instance, Lyme disease often appeared alongside Babesia or Ehrlichia.

The Takeaway
The study found that the "danger level" (how many ticks carry germs) wasn't the same everywhere or at every time of year; it changed depending on where you were and when you looked.

The main goal of this paper is simply to say: "We asked the public for help, we got a huge number of ticks, and here is exactly what we found inside them." This information helps the community understand the current risk of tick bites in their specific area. The researchers have even created interactive maps and a dashboard so people can see these findings in a visual, easy-to-understand way, rather than just reading a list of numbers.

Technical Summary

Problem
Tickborne diseases represent a significant global health burden. In the upper Midwestern United States, Lyme disease, transmitted by the black-legged tick (Ixodes scapularis), is the most prevalent tickborne illness. This vector also carries pathogens responsible for anaplasmosis, babesiosis, and ehrlichiosis. Additionally, there is growing concern regarding the northward range expansion of other tick species, specifically the lone star tick (Amblyomma americanum), which necessitates updated surveillance to assess exposure risks and pathogen carriage in the region.

Methodology
To address these surveillance needs, a citizen science passive tick surveillance program was launched in 2024. The program engaged the public in submitting ticks for analysis to investigate species ranges and pathogen prevalence within the upper Midwest. Over the first two years, the program collected more than 12,000 ticks, with the majority of submissions originating from Wisconsin. The study focused specifically on analyzing adult female I. scapularis (n=707) for the presence of specific pathogens.

Key Contributions and Results
The study yielded several critical findings regarding tick distribution and pathogen prevalence:

• Species Distribution: While adult A. americanum were submitted from areas outside their traditional endemic range, the data did not provide evidence of established populations within the study area.
• Pathogen Prevalence: Analysis of adult female I. scapularis revealed the following infection rates:
  • Borrelia burgdorferi (Lyme disease): 51%
  • Babesia microti: 9%
  • Anaplasma phagocytophilum: 9%
  • Ehrlichia muris eauclairensis: 3%
• Co-infection: Multiple pathogens were detected in 14% of the tested specimens.
• Associations: Significant statistical associations were observed between B. burgdorferi and B. microti, as well as between B. burgdorferi and E. muris eauclairensis.
• Spatial and Temporal Variation: Pathogen prevalences were found to vary across different times and geographic locations within the region.

Significance
The paper claims that these results serve as a foundational step to inform risk assessment for tickborne diseases in the upper Midwest. By leveraging citizen science, the study successfully generated a large dataset to monitor vector ranges and pathogen dynamics. The authors note that the findings are supported by accessible resources, including a non-technical version with interactive maps and an online data dashboard, to facilitate broader understanding and utility of the data.