France identifies first documented human Shamonda virus infection

French health authorities have confirmed the world’s first documented human infection with Shamonda virus in a severely immunocompromised patient who died earlier this month, while emphasising that no wider public health threat has been identified.

The patient was receiving treatment for a serious underlying illness at Hospices Civils de Lyon and died in early October. Officials announced the finding on Thursday, saying investigations were continuing into the circumstances of infection and its contribution to the patient’s condition.

France’s health and agriculture authorities said neurological complications observed before the patient’s death were very probably linked to Shamonda virus. However, the precise role of the infection in the death remains under investigation, according to the European Centre for Disease Prevention and Control (ECDC).

The authorities described the infection as an exceptional occurrence in a person with a severely weakened immune system. They stressed that available scientific evidence had not identified a health risk to the general population, despite the virus having circulated among animals for decades.

Investigators believe the patient may have contracted the virus through the bite of an infected Culicoides midge in eastern France. The region recorded circulation of the virus in livestock during spring and summer, providing a possible geographical connection to the infection.

That explanation remains a hypothesis rather than a confirmed transmission route. Clinical assessments, laboratory examinations and epidemiological inquiries are continuing, involving specialists in human medicine, veterinary health and environmental surveillance.

The ECDC said it was maintaining contact with French authorities and European partners to assess the implications of the discovery. It is also working with a European Union reference laboratory to strengthen testing capacity and help member states identify any additional human infections.

The World Health Organization has been notified, alongside the ECDC, as part of the international response to the unusual finding. No additional confirmed human cases were identified in the information released by European health authorities on Thursday.

Shamonda virus belongs to the orthobunyavirus group and is primarily associated with livestock, especially cattle. It is normally transmitted between animals by biting midges rather than through direct contact. Before the French case, scientists had not documented an infection in a human being.

The virus was identified for the first time in European farm animals during summer 2026. Signs of illness in livestock were observed from June, with laboratory identification following in late July. Its detection in people has therefore come only months after its recognised arrival in European herds.

European animal health surveillance has identified the virus in Austria, Belgium, France, Germany, Ireland, Italy, Liechtenstein, Luxembourg, the Netherlands, Portugal, Spain and Switzerland, as well as Jersey. The geographical spread has prompted veterinary monitoring even though human infections have not otherwise been documented.

France has also identified sporadic infections among smaller ruminants and horses. Cattle are considered the principal animal hosts, but the findings indicate that other domestic species can become infected under conditions that allow transmission by midges.

Germany’s Friedrich-Loeffler Institute, which specialises in animal health, said infections among cattle, sheep and goats had generally produced mild symptoms in affected European herds. Some infected horses, however, had developed serious neurological disorders, with high concentrations of the virus detected in brain tissue after death.

The institute said preliminary investigations were beginning in Germany to determine whether people had antibodies against Shamonda virus. Such testing could help establish whether exposure had occurred without previously being recognised as an infection, although no additional human case has been confirmed.

The ECDC noted that the insects responsible for spreading the virus are generally most active between spring and autumn in Europe. Activity varies according to insect species, geography and weather, and normally declines as temperatures fall.

Public health specialists are examining the case within an approach that considers animal infections, insect vectors and human exposure together, rather than treating them as separate problems. The precise Culicoides species responsible for transmitting Shamonda virus in Europe has not yet been established. That uncertainty complicates efforts to determine where exposure is most likely and which animal populations may be particularly vulnerable.

Shamonda virus was first detected in Nigeria during the mid-1960s and was subsequently identified sporadically in cattle in western, eastern and southern Africa, as well as Japan. Its long history in animals without a documented human infection is central to the authorities’ assessment of this case as unusual.