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As summer heats up, tiny ticks are busy spreading diseases that most Americans have never even heard of, with doctors calling one of them almost akin to Lyme disease in public health risk.
“It is true that both mosquito and tick-borne illness reports, more inclusively called ‘vector-borne’ illnesses, are increasing, in part possibly due to regional climate changes and expanding insect and tick habitats,” Dr. Natasha Wyndham Hanners, infectious disease specialist at Children’s Health and Assistant Professor at UT Southwestern Medical Center, told Newsweek. “It is also true that ease of worldwide travel along with more advanced diagnostic techniques are revealing emergence of previously unknown organisms or organisms new to an area.”
The warning comes as scientists report new findings on how a family of tick-borne viruses called orthonairoviruses can dodge the human immune system, and as public health experts track the spread of ticks carrying dangerous new pathogens across North America.
Together, the developments point to a shifting and expanding map of tick-borne illness in the U.S.
Three Tick-Borne Threats to Know
- Anaplasmosis: A bacterial infection spread by the blacklegged deer tick. It causes fever, headache, chills and muscle aches, but unlike Lyme disease, it produces no bull’s-eye rash, making it easy for patients and doctors to miss without a blood test.
- Orthonairoviruses: A family of tick-borne viruses that includes Crimean-Congo hemorrhagic fever virus, one of the most dangerous pathogens in this group, capable of causing severe hemorrhagic disease in humans. New research shows these viruses carry proteins that strip away the immune system’s warning signals, helping them evade detection.
- Nairoviruses: A broader, emerging class of what the American Chemical Society calls “tick-borne pathogens,” including orthonairoviruses. Researchers have identified a nairovirus, PCTNV, in the Pacific Coast tick in the U.S. It has not been confirmed in humans, but lab tests found its immune-evading enzyme to be the most effective of those studied, raising questions about human exposure risk.
The Virus That Hides From the Immune System
A recently published study from University of California, Riverside shows how orthonairoviruses can suppress the body’s ability to detect infection. Researchers focused on viral proteins called ovarian tumor domain proteases, or OTUs, which strip away small immune-signaling molecules called ubiquitin and ISG15 from human cells. Normally, those molecules act like alarm bells that tell the immune system an infection is underway, but when OTUs remove them, the alarm never sounds and the fight back never happens.
Researchers tested enzymes from four nairovirus species, including three newly identified viruses found in patients in Asia and a virus carried by North America’s Pacific Coast tick, known as PCTNV.
That tick-borne enzyme outperformed the others at stripping away the immune signals, suggesting PCTNV may be especially good at slipping past human defenses.
Since the Pacific Coast tick already bites humans and is known to spread Rocky Mountain spotted fever, the finding raises questions about whether people on the West Coast could also be exposed to this virus, but further investigation is needed to determine whether human exposure is happening within the tick’s range.
“[The] study reinforces the need to be vigilant about not just tick bites but the type of ticks that an individual has been bitten by as they may carry diseases beyond what we have been used to looking for,” Scott Pegan, corresponding author of the study, said in a statement.
Newsweek reached out to the Centers for Disease Control and Prevention (CDC), the University of California, Riverside, and the American Chemical Society for additional comment.
An Old Disease Spreading to New Places
Alongside the emergence of nairoviruses, anaplasmosis, transmitted by the blacklegged deer tick, is spreading into new territory.
“Anaplasmosis is a growing concern because it is transmitted by the common deer tick, the blacklegged tick, but it lacks the famous warning sign of Lyme disease,” Craig Bober, a primary care physician with Inspira Health in New Jersey, told Newsweek. “While Lyme disease is the most common concern, deer ticks can also transmit infections like anaplasmosis and babesiosis, both of which may cause fever, headache, chills, and muscle aches without the bull’s-eye rash.
“Because symptoms of these illnesses often overlap with those of Lyme disease, blood tests are essential to guide appropriate treatment.”
Clinical teams are also watching the Asian longhorned tick, first identified in the U.S. in 2017 and now established in states including New Jersey and Pennsylvania. The tick, whose females can reproduce without mating, is a known carrier of SFTS. While human infections in the U.S. remain rare, experts say its rapid spread calls for greater public awareness.
How to Protect Yourself
Doctors recommend those spending time outdoors wear long sleeves and tuck pants into socks, use EPA-registered repellents containing DEET, picaridin or IR3535, and treat clothing and gear with permethrin.
They advise showering within two hours of coming indoors to wash off unattached ticks, checking the whole body, especially the scalp, behind the ears, underarms and behind the knees. If a tick is attached, grasp it with fine-tipped tweezers as close to the skin as possible and pull straight up, then clean the bite site immediately. The experts recommend consulting a physician soon after, especially if any symptoms arise.
Reference
Gonzalez, D. S., et al. (2026). Insights into the Structure and Function of the OTU Protease Virulence Factors from Emerging Human Nairoviruses. ACS Infectious Diseases. https://doi.org/10.1021/acsinfecdis.6c00320.
Contact Newsweek editors on this story: Kara Dolman and Emma Lee-Sang
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