New Tick-Borne Virus Discovered in China Sickens Over 300 Patients

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A Mystery That Took Years to Solve

The discovery began with a puzzle. For years, roughly 30% of Chinese patients showing classic signs of severe fever with thrombocytopenia syndrome (SFTS) — a serious tick-borne illness — tested negative for the virus known to cause it, Dabie bandavirus (DBV).

Researchers at the State Key Laboratory of Pathogen and Biosecurity in Beijing set out to find out why. Using RNA sequencing and viral isolation on blood samples from patients bitten by ticks, they identified a completely new pathogen: the Asian longhorned tick nairovirus, or ALTNV.

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What the New Virus Does

ALTNV belongs to the orthonairovirus family, a group of viruses distinct from — but related to — the one causing SFTS. Out of 3,163 tested patients, 10.4% carried the new virus. Among those who tested negative for DBV specifically, the rate climbed to 15.1%.

Patients infected with ALTNV alone typically experienced fatigue (84%), gastrointestinal problems (80%), reduced blood platelet counts (38%), and elevated liver enzymes suggesting tissue inflammation (36%). Importantly, none of these single-infection cases were fatal, and patients recovered fully.

The picture changed for the 38 patients who were infected with both ALTNV and DBV at the same time. This group faced significantly higher rates of respiratory problems (61% versus 38%) and kidney impairment (84% versus 66%) compared to DBV infection alone. Seven of these coinfected patients — 18.4% — died.

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Why Two Viruses Together Are More Dangerous

Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children's Hospital in New York, said the pattern reflects how tick-borne infections are often underestimated. "Ticks carry lots of viruses," she noted. "We're getting smarter at identifying those viruses. When one blood sample is negative, it's important to say, 'Maybe there was a new virus there, and let's look for it.'"

Researchers also detected ALTNV directly in ticks: it was present in 1.3% of more than 47,000 ticks collected across 15 Chinese provinces, most commonly in Haemaphysalis longicornis — the Asian longhorned tick — where prevalence reached 1.8%. Laboratory experiments confirmed this tick species can transmit the virus to mice, establishing it as the likely vector.

The study's authors concluded that because ALTNV and DBV circulate in the same regions and share the same tick vector, doctors treating suspected SFTS cases need better tools to tell the two infections apart — especially since coinfection carries a much higher risk profile.

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No Specific Treatment Yet

There is currently no antiviral medication or vaccine targeting ALTNV specifically. "Effective antivirals exist for flu, but not for many tick-borne viruses, including the newly identified one," Nachman said. Treatment for now relies on supportive care — managing symptoms rather than eliminating the virus.

She also cautioned against reflexively reaching for antibiotics, which are ineffective against viral infections. "We certainly don't want to use antibiotics because those only work for bacteria, not for viruses," she said.

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The Tick Is Already in the U.S. — The Virus Is Not (Yet)

The Asian longhorned tick itself is not a distant threat for Americans. According to the U.S. Centers for Disease Control and Prevention, the species was first detected in the United States in 2017, on a sheep in New Jersey, and has since spread to at least 20 states across the eastern half of the country. The U.S. Department of Agriculture has flagged the tick as a serious concern for livestock because a single female can reproduce without mating, potentially creating infestations of thousands of ticks on one animal.

So far, there is no evidence that ALTNV itself has reached the U.S. tick population. But the insect capable of carrying it is already well established domestically, which is why American health officials continue to monitor the species closely for pathogens common in its native range.

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What This Means for Tick Safety

Nachman recommended standard precautions for anyone spending time outdoors in tick-prone areas: wearing long pants tucked into socks, using EPA-approved tick repellent on skin (or on clothing for young children), and checking the body carefully after hikes or time outdoors.

Removing a tick quickly matters. "The longer the tick is on your skin, the more it's engorged, the more it's likely to pass an infection to you," she said.

She stressed that the severity of any tick-borne illness often depends less on the tick species and more on the person bitten. "It's not really about the ticks. It's about the patient. Who are you? What's your underlying illness if you have any? How old are you, and how healthy are you?"

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Outlook

The discovery of ALTNV illustrates how modern gene-sequencing technology is uncovering pathogens that were previously invisible to standard diagnostic tests. Researchers say continued surveillance of both patients and tick populations will be essential to understand how widely the virus has already spread — and whether it poses a growing threat beyond China's borders.

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SOURCES

1. Human Infection with a Novel Tickborne Orthonairovirus Species in China — New England Journal of Medicine (primary study): https://www.nejm.org/doi/full/10.1056/NEJMc2410853
2. Scientists in China discover new tick-borne virus that causes flu-like illness — CIDRAP, University of Minnesota: https://www.cidrap.umn.edu/tick-borne-disease/scientists-china-discover-new-tick-borne-virus-causes-flu-illness
3. Where Ticks Live (Asian longhorned tick distribution) — U.S. Centers for Disease Control and Prevention: https://www.cdc.gov/ticks/about/where-ticks-live.html
4. Asian Longhorned Ticks — U.S. Department of Agriculture, Animal and Plant Health Inspection Service: https://www.aphis.usda.gov/livestock-poultry-disease/cattle/ticks/asian-longhorned

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