A new tick-borne virus has been identified by scientists in China after researchers investigated patients suffering from unexplained fever and flu-like symptoms.
The virus, named Asian longhorned tick nairovirus (ALTNV), belongs to the orthonairovirus genus. Researchers identified it through genetic sequencing after routine testing failed to explain some illnesses among patients with a history of tick exposure.
The findings were published in the New England Journal of Medicine on September 3, 2026. The research could help doctors identify infections that previously went undiagnosed.
Scientists Investigate Unexplained Fever
The discovery came from hospital-based surveillance in areas of China where tick-borne diseases are common.
Researchers examined 3,163 patients with fever and a history of tick exposure. ALTNV was detected through viral RNA or IgM testing in 10.4% of those patients. Among patients who tested negative for Dabie bandavirus, which causes severe fever with thrombocytopenia syndrome, 15.1% tested positive for ALTNV.
Scientists used metatranscriptomic sequencing and virus isolation to identify the previously unknown pathogen.
What Symptoms Does ALTNV Cause?
Patients with ALTNV alone mainly developed an illness resembling influenza.
Fatigue was reported in 84% of patients, while 80% experienced gastrointestinal symptoms. Some patients also developed low platelet counts and elevated aminotransferase levels, which can indicate inflammation or injury involving the liver or other tissues.
The researchers found that patients with ALTNV alone recovered without lasting complications.
However, the picture changed when patients were infected with both ALTNV and Dabie bandavirus.
Coinfection May Increase Disease Severity
Scientists found that 38 patients had both ALTNV and Dabie bandavirus infections.
These patients experienced respiratory symptoms more often than those with Dabie bandavirus alone. Kidney impairment was also more common among coinfected patients.
Seven people with the combined infection died, representing 18.4% of the coinfected group. The researchers therefore warned that simultaneous infections could lead to more severe disease.
The findings highlight why doctors may need to consider more than one tick-borne pathogen when patients develop unexplained fever.
Asian Longhorned Ticks Linked to the Virus
Researchers also investigated ticks to understand how ALTNV spreads.
They detected ALTNV RNA in 1.29% of 47,428 ticks collected across 15 Chinese provinces. The highest detection rate occurred in Haemaphysalis longicornis, commonly known as the Asian longhorned tick, where the rate reached 1.75%.
Laboratory experiments provided additional evidence linking the tick to transmission.
Researchers found that H. longicornis could support several forms of viral transmission and could transmit ALTNV to mice.
Why the Discovery Matters
The discovery could help explain some cases of fever that do not fit existing diagnoses.
Dabie bandavirus is already an important tick-borne infection in parts of Asia. However, more than 30% of patients with clinically suspected severe fever with thrombocytopenia syndrome test negative for the virus.
ALTNV may account for some of these previously unexplained illnesses.
Therefore, better testing could help doctors distinguish between ALTNV and other infections with similar symptoms.
Health Experts Call for Better Surveillance
The researchers say the findings support improved differential diagnosis in regions where these tick-borne viruses circulate.
The two viruses can occur in the same areas and share a tick vector. As a result, doctors may need to consider ALTNV when patients develop fever and other symptoms after possible tick exposure.
For the public, basic tick-bite prevention remains important. People who spend time outdoors can reduce exposure by wearing protective clothing, checking their bodies after outdoor activities and using appropriate insect repellent.
New Virus Highlights Growing Tick-Borne Disease Risk
ALTNV adds to the growing list of tick-borne viruses identified in China.
Scientists continue to investigate how these pathogens move between ticks, animals and humans. They are also working to understand their geographic distribution and potential health impact.
For now, the new findings provide an important warning for doctors and researchers: unexplained fever following tick exposure may sometimes have a cause that standard tests do not detect.
The identification of ALTNV could ultimately lead to better diagnosis and surveillance of tick-borne illnesses in China and other regions where similar vectors are present.
