An individual with cancer in France has become the first person known to contract the Shamonda virus, after an outbreak in livestock in Europe that was first identified in July. The man, aged in his sixties, died on 9 October, 16 days after he started showing neurological symptoms, including vision loss and confusion, according to a case report published in Eurosurveillance this week¹. Infectious-disease researchers say little is known about the virus or how it affects the body.

The man lived in a rural area in the Rhône–Alpes region, where Shamonda virus has been detected in cattle. He was probably infected after being bitten by midges, the report states.

It is also possible that he contracted the virus by eating contaminated food or through a blood transfusion or transplant, although the report’s authors say these routes are less likely. “Investigations are ongoing to rule them out,” they write. Researchers say that the risk of the virus being transmitted between people is low.

Shamonda virus belongs to a family of viruses called orthobunyaviruses, which are known to infect animals such as cows and deer, and are transmitted by mosquitoes and midges, says Krispin Hajkowicz, an infectious-disease researcher at the University of Queensland, Australia. There are no vaccines or antiviral treatments for orthobunyaviruses, Hajkowicz says.

More orthobunyaviruses are being detected in people, says Daniel Rawle, a virologist at the QIMR Berghofer Medical Research Institute in Brisbane, Australia. Climate change and greater contact between wildlife, livestock and humans are some of the factors that have increased the risk of people becoming infected. Another element is that a growing number of people are immunocompromised, and so more at risk of being infected and developing life-threatening symptoms. Although no human-to-human transmission has been recorded for these viruses, during an outbreak of an orthobunyavirus called Oropouche in Brazil in 2024, transmission was reported between pregnant women and their fetuses.

Gene screen

The individual in France, who had leukaemia and was severely immunocompromised, started having seizures shortly after the onset of symptoms and went into a coma, requiring intubation and mechanical ventilation. When his symptoms did not improve after treatment with antibiotics, an antiviral drug and high doses of corticosteroids, he was taken off life support.