Santé publique France said on October 23, 2026, that investigators had identified no human-to-human transmission or risk to the general population after France reported its first documented human Shamonda infection. The patient, who was severely immunocompromised and treated in Lyon, died in early October. French authorities announced the case on October 22.
How investigators identified SHAV-EU1
Neurological symptoms led to broad microbiological and genomic testing, rather than a Shamonda-specific screen. The scientific case report published in Eurosurveillance says metatranscriptomic analysis, which examines genetic material in a sample, detected Shamonda virus Europe 1 (SHAV-EU1) in cerebrospinal fluid. RT-PCR, a molecular test, confirmed the finding.
The report dates the onset of encephalitis, a serious inflammation of the brain, to September 23, 2026. It also describes viral genome detection in serum, respiratory and stool samples at least two months before that onset. The patient had a hematological malignancy and received an allogeneic stem-cell transplant about a month before encephalitis began.
France’s Ministry of Agriculture said the patient’s cerebral complications were very probably linked to the infection. On October 22, virologist Ben Brennan said Shamonda’s contribution to the death remained unclear.
What is known about exposure and transmission
An infected Culicoides biting midge is the leading suspected exposure route, but Santé publique France said the investigation was continuing. The same agency’s October 23 update said investigators had identified no human-to-human transmission. That date-specific finding accompanied its assessment that no risk to the general population had been identified on the knowledge available at the time.
Shamonda is an Orthobunyavirus in the Simbu serogroup and had been identified in animals before this human case. A midge bite is suspected in this patient; it is not an established route of human infection.
What French cattle surveillance counted
As of October 20, 2026, Santé publique France reported Shamonda detections in cattle in 52 departments of mainland France. That figure describes animal surveillance, not human infections. The case report identified the human virus as SHAV-EU1.
