France has confirmed the world’s first documented cases of human infection with Shamonda virus after a severely immunocompromised patient died in early October, leading to an investigation into how the infection occurred and whether it contributed to the death.

The case was announced on Thursday, 22 October 2026, by French health authorities, who said the patient had been receiving treatment for a serious underlying illness in Lyon. The virus had been known to infect animals and was thought to be incapable of infecting humans. Authorities said the case was exceptional due to the patient’s severely weakened immune system.

World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus expressed his condolences to the patient’s family upon the death, emphasising the vulnerability of the patient given their medical condition.

“The patient was immunocompromised, which made them more vulnerable to infection and severe disease, and unfortunately died. My heartfelt condolences to their loved ones,” Tedros said.

However, investigations are ongoing to determine if Shamonda virus caused or contributed to the death. The European Centre for Disease Prevention and Control (ECDC) said it was monitoring the situation closely and working with French authorities and European partners to evaluate the potential public health impact.

French authorities said no health risk to the general population had been identified, based on current knowledge.

The leading hypothesis is that the patient was infected by a Culicoides midge, a small biting insect that transmits the Shamonda virus between animals. French health authorities said the suspected infection with Shamonda virus occurred in eastern France, where the virus had been circulating among livestock during the spring and summer of 2026.

The exact source of the patient’s infection has not been confirmed. Investigations are ongoing to determine how the infection occurred, including identifying how the virus entered the patient’s body and whether it contributed to their death.

In a statement to Anadolu Agency, France’s Health Ministry described the infection as an exceptional case involving a severely immunocompromised patient.

“The Shamonda virus had previously been considered non-transmissible to humans. The infection in this patient therefore constitutes the first documented and reported detection of the virus in a human,” the ministry said.

The detection does not confirm that the virus is readily transmissible between people. At this time, health authorities have not identified a significant public health risk.

Shamonda virus belongs to the Orthobunyavirus group of viruses and has previously mainly infected livestock, including cattle.

The virus was first identified in Nigeria in the 1960s and has occurred sporadically in animals in parts of Africa and Japan. Shamonda virus was first detected in European farm animals in 2026 and has since been detected in livestock in several European countries, according to the ECDC.

In animals, the virus is transmitted by infected Culicoides midges. The appearance of the virus in European livestock led to intensified surveillance by veterinary and public health authorities before the first human infection was detected.

The extent to which Shamonda virus can infect humans and the circumstances in which such infections occur are currently being investigated.

The ECDC said it was working with French and European partners to investigate the implications of the infection. The agency is also supporting efforts to enhance testing capacity and detect any potential additional cases. The investigation will determine whether the French case is an isolated incident or if there have been other undetected human infections.

For now, the authorities have stressed that the patient’s underlying illness and severe immunodeficiency must be recognised as significant contributing factors to the infection and death. As it stands, the death of the patient should not be regarded as confirmation that Shamonda virus presents a serious risk to unimpaired individuals.

The case nevertheless marks a significant development in the surveillance of a virus that has previously only been known to infect animals.

Further information from clinical, laboratory and epidemiological investigations into the case is expected to provide more insight into the circumstances of the infection and its potential implications for public health.