What happened in France?

France's health and agriculture ministries announced on 22 October that a patient in their sixties from a rural part of the Rhône-Alpes region had been infected. The patient was being treated in Lyon for leukaemia and had recently had a stem-cell transplant, leaving their immune system extremely weak.

In late September the patient developed sudden blindness and confusion, then encephalitis (swelling of the brain), and died. Doctors at Lyon's hospitals found the virus by reading all the genetic material in the patient's spinal fluid, after routine tests came back negative. They say the brain illness was "very probably linked" to the virus, though it has not been proven that the virus caused the death.

France informed the World Health Organization and the European Centre for Disease Prevention and Control (ECDC). The WHO called it an isolated case that is unlikely to spread further.

What is Shamonda virus?

  • It belongs to a group of insect-borne viruses called the Simbu group, close relatives of the Schmallenberg virus that hit European farms in 2011–12.
  • It was first identified in Nigeria in the 1960s, and later found in cattle in other parts of Africa and in Japan (from 2002).
  • In summer 2026 it appeared in Europe for the first time: first in cattle in southern Germany, Switzerland and eastern France, and since then in farm animals in 12 countries, including Belgium, the Netherlands, Italy, Spain, Portugal and Ireland.

How does it spread?

Mainly through bites from Culicoides midges — insects smaller than mosquitoes. Animals don't really pass it to each other, except from a mother to her unborn young.

In adult cattle it often causes mild or no illness: fever, tiredness, diarrhoea and a sudden fall in milk. The bigger worry for farmers is pregnant animals, where it can cause miscarriages and birth defects in calves. Sheep, goats and horses can also be infected.

Can humans catch it?

Until now, no human case had ever been documented. Viruses in this group were thought not to infect people at all. Because there is only one case, doctors don't yet know what a "typical" human infection looks like.

  • Person to person: no spread identified. Experts are keeping watch on blood and organ donations as a precaution.
  • Treatment: there is no specific medicine or vaccine — for humans or animals.

Is there any risk to the public?

Officials say no risk to the general population has been identified. Their reasons:

  • it is a single case, in someone whose immune system was severely weakened by cancer treatment;
  • the virus found in the patient had not mutated compared with the strain in animals;
  • there is no sign of human-to-human spread, and no risk identified for farmers;
  • midges are becoming less active as the weather gets colder.

France's director-general of health, Grégory Emery, cautioned that one case is not enough to draw conclusions about anyone — even other people with weak immune systems — and that investigations continue.

Is meat and milk safe?

There is no evidence that the virus spreads through meat, milk or dairy products, and it has not been found in milk. Products from sick animals are already kept out of the food chain.

What should you do?

Nothing special for most people. As always, see a doctor quickly if you have a fever with a severe headache, stiff neck or confusion. People with very weak immune systems should follow their own doctors' advice, which may include avoiding insect bites.

Sources: Santé publique France (English), the Eurosurveillance case report, AP via PBS, ABC News, Euronews, Austria's health agency AGES and the CDC's Emerging Infectious Diseases journal. This article is general information, not medical advice.

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