French health authorities have reported the first documented human infection of the Shamonda virus, a mosquito-borne pathogen previously believed to affect only animals, following the death of a severely immunocompromised patient in Lyon.
The patient, who was receiving treatment for a serious underlying illness at the Hospices Civils de Lyon, died in early October after developing neurological complications. France’s Ministries of Health and Agriculture confirmed on Wednesday that the infection represents “the first documented and reported detection of the virus in a human”.
“The Shamonda virus had previously been considered non-transmissible to humans,” the ministry statement said. “This is therefore an exceptional case involving a severely immunocompromised patient”. Authorities emphasized that, based on current knowledge, “no health risk for the general population has been identified to date”.
The Shamonda virus belongs to the Orthobunyavirus genus and is closely related to the Schmallenberg virus, which emerged in Europe in 2011 and caused reproductive defects in livestock. First identified in Nigeria in the 1960s, the virus circulated sporadically in cattle across Africa and Japan for decades without any known human cases.
That changed in the summer of 2026, when the virus was detected for the first time in European livestock. French authorities identified the pathogen in cattle farms across the Doubs, Jura, Savoie, Haute-Savoie, and Ain regions after a surge of fever and diarrhea cases in cows. Since then, SHAV has been confirmed in livestock across at least a dozen European countries, including Germany, Austria, Italy, Spain, and Switzerland.
The virus is transmitted primarily by biting midges of the Culicoides genus. Investigators believe the French patient was most likely infected through a midge bite in eastern France, where viral circulation among animals was documented during the spring and summer of 2026. The specific midge species involved remains unidentified.
Dr. Ben Brennan, a group leader at the MRC-University of Glasgow Centre for Virus Research, urged perspective on the finding. “The patient had a serious underlying illness that left them particularly vulnerable to infections, and we do not yet know whether Shamonda virus contributed to their death,” he said. “Finding a virus in a severely immunocompromised patient does not necessarily mean it poses a significant risk to otherwise healthy individuals”.
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Brennan noted there is currently no evidence of sustained human-to-human transmission. “The virus is normally spread through biting midges rather than everyday contact between people,” he added.
The European Centre for Disease Prevention and Control (ECDC) said it is monitoring the situation closely and remains in contact with French authorities and European partners to assess potential public health implications. French officials have notified both the World Health Organization and the ECDC.
Clinical, biological, and epidemiological investigations are continuing to determine whether the virus caused or contributed to the patient’s death. Preliminary findings suggest the cerebral complications observed before death were “very probably” linked to the Shamonda infection. The virus was isolated from a cerebrospinal fluid sample and identified as the SHAV-EU1 genotype, showing 99% similarity to a Swiss isolate.
As autumn temperatures drop across Europe, the activity of Culicoides midges is declining, potentially limiting further transmission this season. However, the virus’s broader spread among European livestock – and now its documented leap into a human host – has prompted calls for continued surveillance and research into its pandemic potential.
“While this discovery warrants further scientific investigation and continued surveillance, it does not currently suggest a significant new public health threat,” Brennan said.
