French health authorities have reported the first documented human infection with Shamonda virus, a pathogen previously known to infect animals. The European Centre for Disease Prevention and Control said in a notice dated October 22, 2026, that the infection was identified in a patient treated in Lyon for a serious underlying illness. The patient was severely immunocompromised, making them more vulnerable to infection and complications than the general population.
The patient died in early October. However, the ECDC stressed that clinical, laboratory and epidemiological investigations are still examining whether the virus caused or contributed to the death. The available evidence therefore does not support describing the case as a death definitively caused by Shamonda virus.
No identified risk to the general population
A joint statement from French authorities, published through Inserm, said no risk to the general population has been identified on the basis of current knowledge. The World Health Organization told Reuters that the event appears to be an isolated human case and that wider spread is unlikely at this stage, based on what is known about the transmission of closely related viruses.
Officials say there have been no documented reports of cattle-to-human or human-to-human transmission. The leading hypothesis is that the patient may have been infected through the bite of a Culicoides midge in eastern France, where the virus circulated in animals during the spring and summer of 2026. That route has not been confirmed, and the specific insect species that may have been involved remains unknown.
This distinction is central to responsible risk communication. A first human detection is scientifically significant, but a single case does not show that the virus can spread among people. Authorities also identify the patient’s severe immune deficiency as an important factor when assessing why this unusual infection and its complications occurred.
What is Shamonda virus?
Shamonda virus is an Orthobunyavirus that primarily affects cattle. It was first identified in Nigeria in the mid-1960s and has since been reported sporadically in animals in parts of Africa and Japan. It usually spreads among animals through the bites of Culicoides midges.
Europe recorded its first animal detections in the summer of 2026. According to the ECDC, the virus has since been found in farm animals in Austria, Belgium, France, Germany, Ireland, Italy, Liechtenstein, Luxembourg, the Netherlands, Portugal, Spain and Switzerland, as well as Jersey. Infected cattle may show diarrhoea, weakness, loss of appetite and, less commonly, fever. France has also recorded sporadic infections in small ruminants and equids.
The ECDC says midge activity varies by species, geography and weather. Cooling autumn temperatures generally reduce the activity of most biting midges in Europe, although that seasonal decline does not remove the need for retrospective field and laboratory work to establish how this patient was exposed.
Investigation follows a One Health approach
French agencies said the investigation is being conducted under a “One Health” framework, bringing together expertise in human, animal and environmental health. France has notified both the World Health Organization and the ECDC. The ECDC is also working with the European Commission, the European Food Safety Authority and the relevant European Union reference laboratory to strengthen testing capacity and help member states identify any additional cases.
That work is intended not only to explain the current case but also to ensure that similar clinical presentations can be assessed with appropriate tests. Reference-laboratory support may help countries determine whether any other infections have been missed. No additional human case has been announced.
Authorities are continuing to study the route of exposure, the relationship between the infection and the patient’s neurological complications, and the virus’s ability to cause disease in humans. The official assessment remains cautious but clear: this is an exceptional case that warrants close investigation, not evidence of a community outbreak. There is currently no documented human-to-human transmission and no identified public-health risk to the wider population.
