European health authorities are treating the first confirmed human case of Shamonda virus as a signal for vigilance rather than a cause for alarm, the European Centre for Disease Prevention and Control (ECDC) has said. The case, reported in France, has prompted investigations but no change to the overall risk assessment for the continent.
French health officials confirmed on Thursday that a patient in Lyon, who died in early October, had been infected with Shamonda virus. This marks the first time the virus—previously found only in animals, mainly cattle—has been detected in a human.
Tamás Bakonyi, principal expert on vector-borne and zoonotic diseases at the ECDC, described the case as “very special.” The patient had leukaemia and was “severely immunocompromised,” which likely made the infection easier to establish. “The whole process of viral infections or other kinds of infections are behaving differently in those individuals than in healthy people,” Bakonyi said.
While the possibility that the virus could spread to other humans cannot be ruled out, Bakonyi stressed that “it does not mean that now we should be concerned, that we should be in panic.” He pointed to limited evidence of a broader threat, noting that the patient had been carrying the virus for a long period before developing encephalitis and dying.
What is Shamonda virus?
Shamonda virus belongs to the Simbu serogroup, a family of viruses transmitted by biting midges. It was first identified in Nigeria in the mid-1960s and has since been reported sporadically in cattle across West, East and southern Africa, as well as in Japan.
This summer, the virus was detected in Western Europe for the first time. Cases were reported in Austria, Belgium, France, Germany, Ireland, Italy, Liechtenstein, Luxembourg, the Netherlands, Portugal, Spain and Switzerland, as well as on the island of Jersey. The spread has been linked to warmer temperatures that allow midge populations to thrive and expand northward.
Although Shamonda had never been seen in humans before, Bakonyi said European public health institutes had already been investigating whether it could infect people. “This is an alert, but we have seen this,” he said, adding that millions of people have lived in areas where the virus circulates without any reported problems.
The ECDC is now coordinating with the European Food Safety Authority (EFSA) under a One Health approach, which recognises the close links between animal and human health. They are gathering scientific data and expert input from across member states to inform a formal risk assessment.
Ongoing investigations include clinical, laboratory and epidemiological studies to determine whether the virus caused or contributed to the patient’s death and how the infection was acquired. Researchers are also testing for antibodies in people who may have been exposed, such as veterinarians and farmers, to see if they have been infected without developing symptoms.
The case underscores the importance of surveillance at the animal-human interface. As climate change alters the distribution of insect vectors, Europe is seeing more zoonotic threats. Earlier this year, the continent faced its worst West Nile virus season on record, with infections shifting northward—a trend that public health officials are watching closely.
For now, the ECDC advises that the general public need not change their behaviour. The risk of widespread human infection remains low, and the focus is on understanding the circumstances of this single case. “We should be aware, but not panic,” Bakonyi reiterated.
