On October 7, 2026, health authorities were notified of a case of Shamonda virus infection in a severely immunocompromised patient who was being treated for a serious neurological condition at the Hospices Civils de Lyon and who subsequently died. Initial investigations detected the virus in several biological samples, confirming the patient’s infection with the virus. To date, no human-to-human transmission or health risk to the general population has been identified. Further clinical, biological, and epidemiological investigations are underway, drawing on expertise in human, animal, and environmental health, in particular to determine the most likely modes of transmission and better characterize the potential risks to human health.

What is the Shamonda virus?

The Shamonda virus is a virus of the genus Orthobunyavirus, first identified in Nigeria in the 1960s. The virus is transmitted among animals via biting midges of the genus Culicoides. It primarily affects ruminants (cattle, sheep, and goats), causing transient symptoms such as fever, diarrhea, and decreased milk production, as well as abortions or congenital malformations. The Shamonda virus has also been detected in the central nervous system of horses exhibiting neurological disorders, as well as in alpacas. 

In 2026, a new strain (called Shamonda-Europe) has spread rapidly across Europe since this summer, including in France. As of October 20, 2026, the virus had been detected in cattle in 52 French departments, in sheep in two departments (Oise and Aveyron), and in a horse in the Hérault department. 

• Learn more: ESA platform for detailed, up-to-date animal surveillance data

Does this virus pose a health risk to the general population?

Until now, this virus was believed not to be transmissible to humans. The detection of the first human case of Shamonda virus infection in France is attributable to the exceptional nature of the patient’s health condition, characterized by severe immunosuppression. This detection was made possible by in-depth microbiological investigations conducted by the Hospices Civils de Lyon. 

To date, based on current knowledge, there is no evidence to suggest human-to-human transmission or a health risk to the general population. However, given the unprecedented nature of this detection in humans, investigations are ongoing and aim to:

• determine the most likely modes of transmission;
• rule out any other potential sources of contamination;
• better characterize the potential risks to human health.

At this stage, and taking into account the information reported by the patient’s contacts, the leading hypothesis is transmission via the bite of an infected biting midge (culicoid). However, other hypotheses continue to be explored in order to rule out any other potential sources of infection. The investigations focus in particular on the patient’s environment, their recent travels, and any possible exposure to animals or insect vectors.

What measures have been implemented, and what is the role of Santé publique France?

To better characterize the situation and assess the risks to humans, investigations are continuing in collaboration with various stakeholders:

• the reference laboratories for animal health (ANSES National Reference Laboratory) and human health (National Reference Center for Arboviruses);
• the National Veterinary School of Toulouse;
• the Hospices Civils de Lyon.

Santé publique France is actively monitoring the situation to detect any changes in the epidemiological situation. The National Reference Center for Arboviruses is working to improve biological diagnostic methods to better detect the virus in humans.

To better understand the origin and mechanism of the infection, analyses are underway:

• in patients: complete sequencing of the viral genome and comparison with circulating animal strains, as well as epidemiological and immunological investigations to determine the source of the infection;
• in animals and the environment: genomic surveillance in ruminants, a study of neurological cases in horses, and analysis of Culicoides (midge) collections gathered throughout the season.

Santé publique France integrates this surveillance into a One Health approach and works closely with its partners in the fields of human, animal, and environmental health. This approach, based on the continuous updating and sharing of data, aims to better protect everyone’s health by considering the connections between humans, animals, and their environment.