An immunocompromised elderly man from eastern France died after contracting Shamonda virus, marking the first time the pathogen, known by the abbreviation SHAV, has been confirmed in a human, the World Health Organization said. France's National IHR Focal Point formally notified WHO on October 20, 2026.
The man developed severe neurological symptoms on September 23, 2026, and was diagnosed with encephalitis, an inflammation of the brain. He died on October 8, 2026. Investigators ruled out other causes of encephalitis before confirming SHAV through metagenomic sequencing and reverse transcription polymerase chain reaction testing. High viral loads were found in tissue samples collected after his death.
The patient had no travel history in the year before he fell ill, WHO said. The source and route of his infection remain unknown. Vector-borne transmission is considered the most likely route, while food-borne transmission is also under investigation.
SHAV has until now been recognized solely as an animal-associated virus, with no prior documented cases in humans. It is closely related to Schmallenberg virus, which circulates in Europe. SHAV is currently widespread among animals across Europe, and outbreaks in animals have occurred across much of France.
WHO said the public health risk from SHAV cannot yet be reliably assessed and recommended continued One Health surveillance and further investigation into the virus.