Shamonda Virus

Shamonda virus (SHAV) belongs to a family of viruses called orthobunyaviruses, which are known to infect animals. They most commonly infect cows, but also sheep, goats, horses, and alpacas. In livestock, the virus can cause fever, diarrhea, loss of appetite, reduced milk yield, stillbirth, and congenital abnormalities.

SHAV is transmitted to these animals by the bite of infected Culicoides midges, which are commonly known as biting midges. They are normally more active from spring to fall and become less active as the weather cools. 

SHAV has circulated in Africa and Japan since the 1960’s, but was only documented in Europe in June 2026, when outbreaks in dairy cows and horses occurred in Germany, Switzerland, Austria, Belgium and France. 

On October 22, the French government announced that a man had died from an infection with SHAV.  This was the first known human infection with SHAV. Up until this time, SHAV was not considered to be transmissible to humans.

The man lived in a rural area in the Rhone-Alpes region of France, where SHAV had been detected in cattle. He could have been infected by biting midges or possibly by eating contaminated food. The man had leukemia and was immunocompromised. He developed neurological complications including blindness, confusion, seizures and coma on September 23, 2026. He was hospitalized in Lyon, France, and required intubation and mechanical ventilation. He eventually died ion October 9. No antiviral treatment or vaccine is available.

Postmortem, SHAV was detected in the patient’s cerebrospinal fluid, brain, liver, and spleen. The man’s virus had five genetic changes that have not been found in any sequences from animals, but it was not clear whether these mutations made the virus more infectious to humans.

Currently, the risk of human SHAV infection is believed to be rare. However, climate change and greater contact between wildlife, livestock and humans are some of the factors that may increase the risk of more people becoming infected.

Reference

Bonnet M, et al, Fatal encephalitis caused by Shamonda virus Europe 1 (SHAV-EU1) in a patient with a severely weakened immune system, France, 2026, Eurosurveillance, 2026;31(42):pii=2600883.