New tick-borne orthonairovirus identified in Chinese patients with febrile illness

Researchers in China identified Asian longhorned tick nairovirus (ALTNV) while investigating unexplained illness after tick bites in regions where tick-borne viruses circulate. The investigation, reported in the New England Journal of Medicine, included 3,163 patients treated at sentinel hospitals. RNA sequencing, viral isolation and genetic analyses identified a distinct orthonairovirus. The work addressed cases resembling severe fever with thrombocytopenia syndrome, caused by Dabie bandavirus (DBV), but testing negative for DBV.

ALTNV RNA or immunoglobulin M antibodies were detected in 10.4% of patients overall and 15.1% of those testing negative for DBV. Among patients with ALTNV alone, 84% reported fatigue, 80% had gastrointestinal symptoms, 38% developed thrombocytopenia and 36% had elevated aminotransferase concentrations. These patients recovered completely.

Among 38 patients with ALTNV–DBV coinfection, respiratory symptoms occurred in 61%, compared with 38% of patients with DBV alone; kidney impairment occurred in 84% versus 66%. Seven coinfected patients died (18.4%). ALTNV RNA was also detected in 1.3% of 47,428 ticks sampled across 15 provinces, and laboratory experiments demonstrated transmission to mice by Haemaphysalis longicornis.

The findings support considering ALTNV in the differential diagnosis of tick-associated illness in SFTS-endemic regions. However, this observational comparison does not establish that ALTNV independently worsens DBV outcomes. The secondary report provides no adjusted risk estimates or DBV-only mortality rate, limiting interpretation of the coinfection findings.