Researchers screening thousands of people who had been bitten by ticks found a virus nobody had previously identified circulating in roughly one out of every ten patients. The discovery, from a team at the State Key Laboratory of Pathogen and Biosecurity in Beijing, emerged from an effort to explain why a substantial share of patients with classic tick-borne fever symptoms kept testing negative for the disease doctors expected to find.
A search that started with unexplained cases
The investigation began because roughly 30 percent of patients showing signs and symptoms consistent with Dabie bandavirus infection, a known and sometimes severe tick-borne illness, tested negative for that virus. Rather than treat those negative results as a dead end, researchers screened a total of 3,163 patients who had been bitten by ticks for other possible pathogens. Among the full group, 10.4 percent tested positive for what the team designated the Asian longhorned tick nairovirus, identified through a combination of RNA detection and antibody testing. Narrowing the analysis to patients who had already tested negative for Dabie bandavirus, the positive rate for the new virus rose to 15.1 percent, suggesting it had been quietly filling in a diagnostic gap that standard testing panels missed. The virus belongs to the nairovirus family, a group of pathogens transmitted primarily by ticks that includes several agents already associated with severe hemorrhagic disease elsewhere in the world, which is part of why researchers moved quickly once initial screening pointed toward an unclassified pathogen rather than simply a variant strain of something already known.
Fatigue, stomach trouble and signs of liver stress
Patients infected with the new virus alone, without a second infection layered on top, tended to develop a cluster of symptoms familiar from other tick-borne illnesses: fatigue, gastrointestinal problems, a drop in platelet count known as thrombocytopenia, and laboratory signs of liver-cell injury or inflammation. Most of these single-infection patients recovered fully, according to the study team’s findings. The overlap with symptoms of other tick-borne fevers is part of why the virus went undetected for as long as it did, since a patient presenting with fatigue and gut symptoms after a tick bite would typically be tested for already-known pathogens rather than screened broadly for something unclassified. Thrombocytopenia in particular, the drop in blood platelets that showed up in more than a third of single-infection cases, is a marker doctors already watch for in suspected tick-borne fever, which likely means a meaningful number of prior cases carrying the new virus were logged under a broader, unresolved diagnosis rather than left completely unexplained.
A sharper danger in co-infected patients
The picture changed considerably for the smaller group of patients infected with both the new virus and Dabie bandavirus at the same time. Thirty-eight patients fell into that co-infected category, and compared with patients carrying Dabie bandavirus alone, they showed higher rates of respiratory symptoms, 61 percent versus 38 percent, and higher rates of kidney impairment, 84 percent versus 66 percent. Seven of those co-infected patients, or 18.4 percent of the group, died during the course of the study, according to Fox News’s reporting on the findings. That fatality rate among co-infected patients stands in sharp contrast to the largely full recovery seen in patients carrying the new virus by itself, underscoring that the danger appears tied heavily to combination infections rather than the new virus acting alone.
The tick behind the discovery
The virus takes its working name from its vector, the Asian longhorned tick, a species scientifically known as Haemaphysalis longicornis. The tick is notable well beyond this single study because it has become an invasive species in parts of the world far from its native range, including documented populations established in the eastern United States over the past several years. Unlike many tick species, the Asian longhorned tick can reproduce without mating, allowing a single tick to found a new population on its own, a trait that has helped it spread quickly once introduced to a new area.
That reproductive quirk has made the species a recurring subject of public health monitoring wherever it turns up, since a handful of ticks carried in on livestock, wildlife or travel gear can seed a self-sustaining population within a single season. Agricultural and health agencies in several states have tracked its expansion for years, largely in connection with its role in transmitting other pathogens to livestock and pets, and the newly identified virus adds one more reason for that surveillance to continue.
Why there is no targeted treatment yet
One of the more sobering findings from the research team, summarized by CIDRAP, is the current absence of any antiviral drug specifically effective against the newly identified virus. Effective antivirals exist for common seasonal threats like influenza, but that pharmaceutical infrastructure has not caught up with the growing list of tick-borne viruses being identified through more sensitive modern screening methods. For now, treatment for infected patients centers on supportive care, monitoring for the complications seen in co-infected cases, and managing symptoms as they arise rather than targeting the virus directly.
How it compares to a better-known relative
Dr. Sharon Nachman of Stony Brook Children’s Hospital, commenting on the findings, pointed to the related illness known as severe fever with thrombocytopenia syndrome, or SFTS, as a useful point of comparison. That related tick-borne disease carries a mortality rate of roughly 30 percent in documented cases, according to Nachman’s assessment cited in reporting on the discovery. Set against that benchmark, the newly identified virus’s apparent behavior, generally mild when acting alone but considerably more dangerous in combination with a second tick-borne infection, fits a pattern researchers have increasingly documented across this family of pathogens as testing has grown sophisticated enough to catch co-infections that older diagnostic methods would have missed entirely.
Researchers involved in the work have indicated that broader surveillance is a logical next step, both to determine how widely the virus circulates beyond the initial patient cohort and to establish whether it appears in tick populations outside the region where the original samples were collected. Until that surveillance expands, clinicians treating patients with unexplained tick-borne symptoms are being encouraged to consider the new virus as a possibility when standard panels come back negative, rather than closing the file on an otherwise unexplained illness.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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