Ticks carrying bacteria that can cause severe illness have been found farther south than ever before, researchers with the Centers for Disease Control and Prevention and other institutions said in a new report.
Blacklegged ticks carrying bacteria that cause anaplasmosis and hard tick relapsing fever were discovered during testing by tick researchers in North Carolina, as they sought to figure out whether another disease borne by ticks has become endemic outside its typical area.
Anaplasmosis, primarily spread to humans through infected blacklegged ticks, can cause symptoms such as fever and muscle aches.
If not treated, or sometimes even with treatment, more severe symptoms such as respiratory failure are possible, and some people have died.
Hard tick relapsing fever spreads when infected ticks bite people. Symptoms can include fatigue and headaches.
Recovery often happens without treatment, although relapses are possible.
The researchers collected 373 ticks from November 2024 to August 2025. About three-quarters were blacklegged ticks.
Of the blacklegged ticks, 40 percent tested positive for the bacteria that causes Lyme disease.
Four of the ticks tested positive for the strain of bacteria that causes anaplasmosis in humans, and two had the bacteria that causes hard tick relapsing fever.
The findings “highlight the potential for pathogen transmission in a new geographic area” and show that efforts to raise awareness of the development among both doctors and the public are important to facilitate diagnosis and treatment, as well as prompt protective measures such as wearing long pants and tall socks when venturing outdoors, the researchers said on Aug. 13.
Ticks are arachnids that are primarily present in wooded and grassy areas. They are known to latch onto people and animals that pass by them.
The researchers also said that health care providers should know that Lyme disease is spreading outside of its typical area, which is the Northeast and Upper Midwest.
“Lyme disease can be a life-changing diagnosis, especially if not diagnosed and treated early,” Dr. Ross Boyce, associate professor of medicine at the University of North Carolina, said in a statement.
“The pace at which we’ve gone from zero-to-sixty, essentially within a 10-year period, means that we are behind. We need a focused and dedicated response to what I would consider a regional epidemic.”
The researchers are working on ways to reduce tick populations and surveil more areas outside Biltmore Forest, where the ticks were collected.
Limitations of the study, the researchers said, included a limited ability to determine the density of ticks because the surveillance covered a relatively small area, creating “a heightened risk of selection bias.”
