France reports first human Shamonda virus case; officials say public risk low

French authorities have reported the first known human case of the Shamonda virus (Shav), detected in a patient who died in early October. The country’s health and agriculture ministries said in a joint statement that the infection was an “exceptional case in a severely immunocompromised patient” and that there was currently no risk to the public.

Shav primarily affects cattle and can be spread by infected midges, small biting insects that can carry the virus between animals. Cases have also occurred in sheep, goats, alpacas and horses. Until now, infections in people had not been recorded, despite decades of circulation of the virus in Africa and Asia, the ministries said.

The World Health Organization (WHO) confirmed that this was the first documented human case of the disease. It said it had not yet made its own formal risk assessment, but that current information and knowledge of similar diseases suggested the case was isolated and “unlikely to lead to wider spread at this time.” The WHO added that the transmissibility of midge-borne viruses generally declines during the cooler months of the year.

French officials are still investigating how the virus spread to a human. It is currently thought the patient contracted Shav through a midge bite in eastern France, where cases were first identified in animals in the spring. The patient had been treated for a serious illness in a Lyon hospital and experienced neurological complications that initial findings suggested were “very likely linked” to the virus. The statement stressed that the patient’s immune system was weakened, leaving them more vulnerable to illness.

The European Centre for Disease Prevention and Control (ECDC) said it was working with French and European partners to investigate the “potential public health implications” of the infection. The agency said the first cases of the virus in Europe were identified in late July. Since then, it has been detected in farm animals in several countries, including Ireland, Germany, Italy and Spain, as well as in Jersey.

In animals, dairy herds that catch Shav from bites can experience fever, diarrhoea and poor milk production. The virus is not known to spread from person to person, and officials said the current evidence pointed to an isolated case.

Midges are small biting flies that can transmit viruses between animals. Health officials said the case was exceptional because the patient was severely immunocompromised, and they stressed that the detection did not change the assessment that the risk to the public was low.

The French ministries noted that the Shamonda virus had been considered non-transmissible to humans until this case. They said the detection showed the importance of continued surveillance of animal and human health, while stressing that the risk to the general public remained low.

The WHO and ECDC said they were monitoring the situation. Public health advice remained unchanged, and officials did not call for any additional precautions beyond routine measures against midge bites in affected areas.