French authorities are investigating an infection in a severely immunocompromised patient, with no risk to the general population identified at this stage
Shamonda virus has been identified in a human patient for the first time, prompting an investigation by French health authorities into an infection previously associated with livestock.
The patient, who was severely immunocompromised and receiving treatment for a serious illness at the Hospices Civils de Lyon, died in early October. Authorities say cerebral complications observed before the patient’s death were very likely linked to the infection, although clinical, biological and epidemiological investigations remain underway.
Announcing the finding on 22 October, the French government describes it as an exceptional case. Based on current knowledge, authorities have identified no health risk to the general population.
The leading hypothesis is that the patient acquired the infection through the bite of a Culicoides midge in eastern France, where the virus circulated among animals during spring and summer 2026. The route of infection has yet to be confirmed.
Human and animal health
Investigators are combining expertise in human, animal and environmental health through a One Health approach. French authorities have notified the World Health Organization and the European Centre for Disease Prevention and Control.
Shamonda is an orthobunyavirus first identified in Nigeria in the mid-1960s. It has circulated for decades in parts of Africa and Asia without a previously documented human infection.
Cattle are considered its main animal hosts, although infections have also been detected in other species. The virus was identified in European livestock during summer 2026, including in France.
European surveillance
In the British Isles, the UK Animal and Plant Health Agency (APHA) detected Shamonda virus in cattle in Jersey in August, announcing the finding on 24 September.
In cattle, reported symptoms include fever, diarrhoea, lethargy and reduced milk production. Abortions have also been documented, with concerns that infection during pregnancy could cause congenital abnormalities similar to those associated with the related Schmallenberg virus.
APHA has also reported detections in sheep, goats, alpacas and horses across several European countries. Investigations are continuing into the association between Shamonda infection and neurological disease in horses, including cases in Germany and Switzerland.
The agency has developed diagnostic testing and encourages veterinary investigation of animals showing compatible symptoms, which can overlap with other livestock diseases.
For the human case, the immediate priority remains establishing the circumstances of infection and its clinical consequences. The French assessment continues to distinguish this exceptional finding in a severely immunocompromised patient from the risk to the wider population.
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