You have probably done the check after a walk in the woods, hands running down your ankles, scalp and waistband.
Most people never think a bite might do more than raise an itchy bump. For years, though, doctors saw patients who felt far sicker than that.
Now researchers have identified a previously unknown tick-borne virus that may be behind many of those unexplained flu-like illnesses.
The team, based in Beijing, published the discovery in September 2026 in the New England Journal of Medicine.
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The virus is called Asian longhorned tick nairovirus, or ALTNV. Its main carrier is a small tick species that has been spreading rapidly through the eastern United States since 2017.
What ALTNV looks like in the patients studied
In the study, researchers tested 3,163 patients in China who had come down with fever after a tick bite. About one in ten tested positive for ALTNV.
The most common complaints among those infected with ALTNV alone were fatigue and gastrointestinal problems, with 84 percent reporting fatigue and 80 percent reporting stomach or bowel symptoms.
Nearly four in ten showed low platelet counts on blood tests.
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Every patient with ALTNV alone recovered fully.
The danger appeared when two viruses met at once
The concerning finding involved patients who carried a second tick-borne virus at the same time.
That second virus, Dabie bandavirus, causes a serious condition called severe fever with thrombocytopenia syndrome, meaning severe fever with a dangerous drop in the blood cells that help clotting.
Among 38 patients infected with both viruses, seven died. That works out to a fatality rate of 18.4 percent, with far higher rates of breathing trouble and kidney damage than in patients with the second virus alone.
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The authors note that the two viruses circulate in the same areas and share the same tick. In regions where the more severe disease is already known, doctors need better tools to tell the two infections apart.
What this means for tick season in the United States
The Asian longhorned tick was first spotted in the United States on a sheep in New Jersey in 2017. As of April 2026, the tick had been reported in 24 eastern states, according to the Alabama Department of Agriculture and Industries.
There is no evidence yet that ALTNV itself is circulating in the United States. According to Stony Brook Medicine, the tick that carries the virus is present in parts of the country, but the virus has so far only been documented in patients in China.
The usual tick precautions still apply for anyone outdoors this fall. Use tick repellent, wear long pants and consider tucking them into socks in grassy or wooded areas. Check yourself, your children and your pets after coming back inside.
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Pay close attention to the scalp, behind the ears, the waistline and the backs of the knees. If you find a tick, remove it promptly with fine-tipped tweezers.
Anyone who develops a fever, deep fatigue or unusual bruising in the days or weeks after a tick bite should see a doctor and mention the exposure.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.