Researchers in China have identified a previously unknown tick-borne virus that showed up in roughly one of every ten feverish patients tested after a tick bite, and turned dangerous mainly when it struck together with a virus doctors already watch for. The findings, from scientists at China's State Key Laboratory of Pathogen and Biosecurity, were published Sept. 2 in the New England Journal of Medicine.
The team set out to explain why many patients with suspected severe fever with thrombocytopenia syndrome, or SFTS, tested negative for the illness's known cause, Dabie bandavirus. Screening 3,163 feverish patients with a history of tick exposure, they detected a new virus, named Asian longhorned tick nairovirus, or ALTNV, in 10.4% overall, and in 15.1% of patients who had tested negative for DBV.
Among the 56 patients infected with ALTNV alone, the illness looked mostly like a bad flu: fatigue in 84%, gastrointestinal symptoms in 80%, low platelet counts in 38% and elevated liver enzymes in 36%, with every patient recovering fully. The picture changed for the 38 patients co-infected with both ALTNV and DBV, who were more likely to develop respiratory symptoms (61% versus 38% for DBV alone) and kidney impairment (84% versus 66%); seven of them, or 18.4%, died. Testing nearly 47,500 ticks collected across 15 provinces, researchers detected ALTNV in 1.29% overall, rising to 1.75% in the Asian longhorned tick, Haemaphysalis longicornis — the species that appears to be its main carrier.
An Invasive Tick Already in the US
The Asian longhorned tick is not just a China problem. The species, native to East Asia, has spread rapidly since it was first detected in the United States in New Jersey in 2017, and has since turned up in close to twenty states along the East Coast and beyond, according to entomologists who track the tick's range. ALTNV itself has not been reported outside China, and researchers caution the new findings are specific to a region where ALTNV and DBV already circulate together — but the tick's US foothold means public health officials are paying attention.
Outside experts said the discovery reflects improving diagnostic tools rather than a sudden new threat. Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children's Hospital, told Fox affiliates covering the study that "we're getting smarter at identifying those viruses," and stressed the value of retesting patients whose initial samples come back negative.
"Cocirculation of the two viruses and their shared tick vector underscore the need for improved differential diagnosis."
Study authors, New England Journal of Medicine
There is no specific antiviral treatment for ALTNV; care for infected patients is supportive. The study's authors are calling for wider surveillance of tick populations and more systematic testing for the new virus in places where SFTS is already endemic, particularly given how much more severe outcomes were among patients carrying both pathogens at once.
