A severely immunocompromised man in France died after contracting the Shamonda virus, marking the first known human infection.
Patient history and death
What is the Shamonda virus
What we know
- The virus was first identified in cattle in Nigeria in 1965, or the mid-1960s.
- It spreads through the bites of tiny insects called Culicoides midges.
- In animals such as cattle, sheep, goats, horses and alpacas, it causes fever, diarrhoea and reduced milk production.
- The virus is rarely deadly to adult animals, but infected pregnant animals can transmit it to their foetus, resulting in miscarriage, stillbirth or birth defects.
- There are no vaccines to protect animals or people from Shamonda infections.
- Shamonda belongs to the same genus as the Oropouche virus, which caused 9.4 million human infections in Latin America and the Caribbean between 1960 and 2025.
Still unclear
- How the virus leaped from animals to humans.
- Whether Shamonda infected humans before and went unnoticed because no one died.
Arrival in Europe and spread
- 1965Discovery
The Shamonda virus is first identified in cattle in Nigeria.
- End of JulyEuropean arrival
The virus is detected in Europe for the first time, including on cattle farms in France.
- 9 October 2026First human death
A 61-year-old leukemia patient dies at the Civil Hospital of Lyon after life support is withdrawn.
- 22 October 2026Public confirmation
French health authorities announce the first known human detection.
The infection and investigation
On 22 October 2026, French health authorities confirmed the livestock virus had been detected in a human for the first time. The patient, who was severely immunocompromised, died earlier this month.
The 61-year-old man was being treated for leukemia at the Civil Hospital of Lyon when he contracted the disease. After a stem cell transplant, he developed fatal brain swelling, known as encephalitis.
A joint report by the French Health and Agriculture Ministries said the immunocompromised patient experienced blindness and confusion before his death, and that the neurological complications were very likely linked to infection with the Shamonda virus. The report stated: "The neurological complications observed in the immunocompromised patient prior to his death are very likely linked to infection with the Shamonda virus".
He entered a coma and died on 9 October 2026, after doctors ended life support. No earlier case is known of a person contracting the disease and dying from it.
Officials suspect the patient was bitten by an infected midge in eastern France. The ministries said the virus circulated in animals in that region during the spring and summer.
Genetic testing revealed traces of a new European clade, SHAV-EU1, in the deceased person's cerebrospinal fluid, urine and saliva. The report said two new clades, SHAV-EU1 and SHAV-EU2, had been detected earlier this year.
The ministries described the human infection as "an exceptional case involving a severely immunocompromised patient" hospitalised for a serious medical condition, and said there is "no health risk to the general public identified at this time".
Although the virus has circulated in Africa and Asia for several decades, the ministries said no human cases of Shamonda virus had been detected before.
How the disease-causing virus leaped from animals to humans in the first place is still being investigated.
Grégory Destras, a clinical virologist and co-author of the report, said, "At this stage, there is no evidence that the Shamonda virus will become more common in humans". He suggested the virus might have remained in the patient for several weeks, multiplying before neurological symptoms developed.
Destras also proposed testing stored samples from immunocompromised people to identify asymptomatic infections and determine the true scale of Shamonda in France.
Martin Beer, a veterinary virologist at the Friedrich Loeffler Institute in Germany, said biting midges transmit infections quickly during summer and autumn. "In winter the transmission cycle stops since the number of biting midges is very low and temperatures below approximately 12 degrees Celsius do not allow efficient virus replication".
Beer pointed out that other viruses from this family have caused unexplained brain swelling in immunocompromised people infected with members of the orthobunyavirus group, including Jamestown Canyon and Cache Valley viruses.
Natasha Tilston-Lunel, a virologist at Indiana University School of Medicine who was not associated with the new study, noted that the Schmallenberg virus is closely related to Shamonda and widespread in livestock, but not humans. She suggested Shamonda may also have limited infectiousness among people.
The case report published in Eurosurveillance said the virus was first identified in cattle in Nigeria in 1965. Another account places its first detection in Nigeria in the mid-1960s. Cattle infections have also been recorded in Japan and multiple parts of Africa.
At the end of July, Shamonda appeared on French cattle farms, marking its first arrival in Europe. French animal health monitors said it has now been detected in livestock across 14 European countries. A separate report specified 14 western European countries, referring to an epidemiological bulletin issued by France's national institute for animal health research.
Shamonda is part of the Simbu serogroup and the Orthobunyavirus genus, as is Oropouche virus. Between 1960 and 2025, Oropouche virus infected 9.4 million people in Latin America and the Caribbean regions.
There are currently no vaccines to protect animals or people from Shamonda infections.
Officials said they had sent the findings to the World Health Organization and the European Center for Disease Prevention and Control. The ECDC spokesperson said the agency needs clarity on the virus's transmission and the role vectors play in infecting people.
Clinical, biological and epidemiological investigations are still ongoing, according to the French ministries.
