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  • Posted Wednesday October 20, 2021

Citizen-scientist study fuels launch of first interactive U.S. county map of ticks carrying diseases

Study finds ticks carrying disease-causing bacteria in 116 U.S. counties where they have not been previously documented by CDC

FLAGSTAFF, Ariz., and PORTOLA VALLEY, Calif. — Oct. 20, 2021 — A study jointly led by the Translational Genomics Research Institute (TGen), Northern Arizona University and Colorado State University, in partnership with the Bay Area Lyme Foundation (BAL), has identified ticks carrying disease-causing pathogens in 116 counties across the nation not previously identified by the U.S. Centers for Disease Control and Prevention (CDC). TGen is an affiliate of City of Hope.

As a result of the study’s findings — published in the journal mSphere — BAL, a leading nonprofit funder of innovative Lyme disease research in the U.S., today announced the launch of interactive national tick maps of U.S. counties.

“These maps will be eye-opening for many Americans as it makes it easy to see that ticks carrying disease-causing bacteria can be commonly found across the U.S.,” said Tanner Porter, M.S., a Research Associate in TGen’s Pathogen and Microbiome Division, and the study’s lead author. “If you aren’t aware of the possibility of ticks, either in your backyard or while traveling, you are unlikely to look for them. But an unseen tick can still transmit a pathogen and cause disease. It is important for everyone to know to look for ticks, be aware of the pathogens that they carry, and takes steps to mitigate their risk.”

Citizen-scientists collected and provided the ticks evaluated in the study as part of BAL’s Free Tick Testing program, which collected more than 20,400 ticks, of which 8,954 are Ixodes ticks capable of carrying the most common tick-borne pathogens.

“We continue to expand the area known to harbor disease-carrying ticks, and we hope people across the U.S. will use this interactive map to learn more about the risks for their hometowns, their family’s residences and vacation spots,” said Linda Giampa, Executive Director of the Bay Area Lyme Foundation. “The citizen-scientists contributing to this study allowed the country’s collective tick knowledge to advance further than even the CDC could do at this time. Gaining the support of citizen-scientists allowed us to collect from many counties across the country where ticks are not usually collected and tested, or they are not tested for these pathogens.”

The types of ticks that were tested were:

  • Borrelia burgdorferi sensu lato, the group which causes Lyme disease.
  • Borrelia miyamotoi, which causes tick-borne relapsing fever.
  • Anaplasma phagocytophilum, which causes human granulocytic anaplasmosis.
  • A protozoan pathogen known as Babesia microti.

Lyme disease findings
Overall, Borrelia burgdorferi sensu lato, the bacterium that causes Lyme disease, was identified in 293 U.S. counties across 29 states, and in 1,279 (14%) of the ticks submitted. Lyme bacteria were found in ticks in 75% of all counties in the Northeastern United States, and in 23% of ticks submitted from this region. In the Midwest, the bacteria were found in 78% of counties. In the West, Lyme bacteria were found in ticks in 26% of the surveyed counties. And in the South, Lyme bacteria was found in ticks from 15% of the surveyed counties, where the prevalence of the bacteria among submitted ticks was 3%.

Tick borne relapsing fever findings
The bacteria which causes tick borne relapsing fever, Borrelia miyamotoi, was identified in 80 counties, primarily in the Northeast and West. Approximately 1% (113 ticks) of the ticks tested from the Northeast were carrying carried the bacteria. The bacteria were also detected in 2.5% of Southern counties, and 4% of those in the West.

Anaplasmosis findings
The bacteria causing human granulocytic anaplasmosis, a tick-borne disease carried by ticks that can lead to organ failure, was detected in 128 counties across the U.S. with a prevalence of up to 5.3% among ticks in each county. This included 42% of counties in the Northeast, 20% of counties in the Midwest, and 24% of counties in the West.

Babesiosis findings
Babesia microti was identified in 71 counties in the Northeast, Midwest and South, with an average of 2% of ticks submitted from these counties carrying the parasite. Babesia microti was not detected in any ticks in the West. A related parasite, Babesia duncani, is found in Western states but was not evaluated in this study.

Typical tick collection methods involve researchers canvasing various terrain with large sheet-like material, which collects ticks, but does not take into account a tick’s natural attraction to mammals. The limitations of citizen studies include uneven awareness of the program across geographic areas, the fact that ticks may remain attached to a person as they travel, and reliance on motivation of people who encounter ticks.

The BAL-supporter tick-testing initiative was conducted initially by a scientific group at NAU led by the late Nate Nieto, Ph.D., which was based on ticks collected from citizen-scientists from January 2016 through August 2019. Ticks were submitted from every state except Alaska. The program received a six-fold increase in tick submissions over initial estimates, representing an unprecedented national coordination of a citizen-science effort and diagnostic investigation.

The study — Citizen Science Provides an Efficient Method for Broad-Scale Tick-Borne Pathogen Surveillance of Ixodes pacificus and Ixodes scapularis across the United States — was published in mSphere, a multidisciplinary open-access journal of the American Society for Microbiology.

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About Lyme disease
The most common vector-borne infectious disease in the country, Lyme disease is a potentially disabling infection caused by bacteria transmitted through the bite of an infected tick to people and pets. If caught early, most cases of Lyme disease can be effectively treated, but it is commonly misdiagnosed due to lack of awareness and unreliable diagnostic tests. Even with these challenges, it is estimated that there are nearly 500,000 new cases of Lyme disease each year, according to the most recent CDC statistics.

About TGen, an affiliate of City of Hope
Translational Genomics Research Institute (TGen) is a Phoenix, Arizona-based nonprofit organization dedicated to conducting groundbreaking research with life-changing results. TGen is affiliated with City of Hope, a world-renowned independent research and treatment center for cancer, diabetes and other life-threatening diseases:  This precision medicine affiliation enables both institutes to complement each other in research and patient care, with City of Hope providing a significant clinical setting to advance scientific discoveries made by TGen. TGen is focused on helping patients with neurological disorders, cancer, diabetes and infectious diseases through cutting-edge translational research (the process of rapidly moving research toward patient benefit). TGen physicians and scientists work to unravel the genetic components of both common and complex rare diseases in adults and children. Working with collaborators in the scientific and medical communities worldwide, TGen makes a substantial contribution to help our patients through efficiency and effectiveness of the translational process. For more information, visit: Follow TGen on FacebookLinkedIn and Twitter @TGen.

TGen Media Contact:
Steve Yozwiak
TGen Senior Science Writer
[email protected]

About Bay Area Lyme Foundation
Bay Area Lyme Foundation, a national organization committed to making Lyme disease easy to diagnose and simple to cure, is the leading public not-for-profit sponsor of innovative Lyme disease research in the US. A 501c3 non-profit organization based in Silicon Valley. Bay Area Lyme Foundation collaborates with world-class scientists and institutions to accelerate medical breakthroughs for Lyme disease. It is also dedicated to providing reliable, fact-based information so that prevention and the importance of early treatment are common knowledge. A pivotal donation from The LaureL Foundation covers overhead costs and allows for 100% of all donor contributions to Bay Area Lyme Foundation to go directly to research and prevention programs. For more information about Lyme disease or to get involved, visit or call us at 650-530-2439.

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