What Is Shamonda Virus? First Human Case in France and Implications for Infection Prevention

On October 22, 2026, French health authorities reported something no one had documented before: a person infected with Shamonda virus, a midge-borne virus previously known only in animals.^1-3 The patient was severely immunodeficient, receiving care for a serious illness at a hospital in Lyon, and died in early October.¹

As an infection preventionist (IP), when I envision an emerging pathogen entering my facility, I think about high fever and a history of exotic travel. This virus did not need to travel far; it had already been circulating among farm animals in Eastern France since the summer.¹

What authorities have shared about this patient’s illness comes down to 2 words: complications cérébrales, or brain complications. According to what has been reported so far, those complications were very probably linked to the virus.¹ Whether the virus caused or contributed to the death, and how the patient became infected, are still under investigation.²

That gap is what makes the story. One case tells us this virus is able to infect a human. What it cannot tell us is how often, how severely, or whether the virus is transmissible from person to person.

The Clinical Picture in Lyon

Today, not very much. Using a One Health approach, subject matter experts specializing in human disease, animal disease, and environmental health are working together to determine how this happened.¹ French authorities are collecting information on the source of infection and possible routes of transmission to inform the investigation and identify whether there is any potential risk to public health.³

The patient’s age, sex, underlying illness, date of symptom onset, how the infection was diagnosed, and which specimen tested positive have not been released. What has been officially reported is in Figure 1.

Microbiology Baseline: From West Africa to Europe

For the microbiology refresher: Shamonda virus belongs to the genus Orthobunyavirus in the family Peribunyaviridae, within the Simbu serogroup of related viruses.^4,5 It is an enveloped virus with a negative-sense, single-stranded RNA genome.^4,5

Shamonda virus was first detected in Nigeria in the mid-1960s and has been reported sporadically in cattle in West, East, and southern Africa and in Japan.¹ In Japan, it was linked to malformed calves in 2015 and 2016.⁶ In South Africa, it turned up in Culicoides biting midges in 2017 and in an aborted goat fetus in 2021.⁴ In this case, the European species of the midge has not yet been identified (Figure 2).²

In Europe, signs of illness in animals were first reported in June, the virus was identified in late July, and it has since been found in farm animals in 12 countries and on the Channel Island of Jersey.² Cattle are the main hosts, and this summer, France also identified sporadic infections in sheep, goats, and members of the horse family.¹

Unraveling the Transmission Route

The leading hypothesis is a bite from an infected Culicoides midge in eastern France, where the virus circulated in animals during spring and summer 2026.¹ WHO Director-General Tedros Adhanom Ghebreyesus notes the patient was in an area where the virus was circulating in animals and where these midges were present.³ The European Centre for Disease Prevention and Control (ECDC) says the midge species involved is still unknown and that midge activity is declining with cooler weather.²

Key questions remain open:

• Where the patient lived, worked, or traveled during the likely exposure window.
• Whether the patient had contact with cattle, small ruminants, or horses.
• Whether the patient received blood products, tissue, or an organ before becoming ill. No statement mentions these routes, and none rules them out.
• Which viral clade, or genetic lineage, infected the patient, and whether it matches the virus circulating in nearby herds.
• Whether the virus was detected before or after the patient’s death.

Lessons from the Field: Neurotropism in Livestock

What we know is limited to animal cases. Affected French dairy herds saw diarrhea, depression or loss of appetite, less consistent fever, and drops in bulk milk production ranging from 15% to 75%.⁵ France’s agriculture ministry describes most adult signs as transient.⁷

The impact on pregnant cows is more significant. In France, typically 2 to 4 weeks after a herd fever episode, pregnant cows have been reported to experience spontaneous abortions. When autopsied, viral RNA was detected in placentas and fetal organs, including the brain.⁵

In Japan, 15 calves exposed in the womb were born with rigid, bent limbs, curved spines, and twisted necks. Viral RNA was found in the brain or spinal cord of 7, and tissue examination showed brain inflammation and loss of nerve cells in the spinal cord.⁶

Horses tell a similar story. In Switzerland, viral genetic material was found in the brains of 2 horses with central nervous system disease.⁸ In those horses, the virus was detected only in brain tissue. Blood and cerebrospinal fluid tested negative, which the investigating institute suggests may reflect a shorter viremia in horses than in cattle.⁸ In France, by contrast, the virus has been detected in both the brain and the blood of horses with neurological disorders, though a causal link has not been fully established.⁹

In cattle and horses, the most serious findings reported so far involve the nervous system.^6,8

So, is Shamonda virus fatal? One infected person has died, and investigators have not yet determined whether the virus caused or contributed to that death.² A single case, with no count of undetected infections, is not a fatality rate. The honest answer is that we do not know.

Evaluating Human Transmission and Vector Risks

Nothing in the record suggests it has. No second human case has been reported,² and French authorities have identified no health risk to the general population to date.¹ Among animals, France’s agriculture ministry reports no evidence of significant direct transmission, apart from mother to offspring during pregnancy.⁷

If a Simbu serogroup virus spreads between people, the precedent is a midge, not contact. Oropouche virus, a member of the same serogroup, shows how that works in cities: infected people carry enough virus in their blood for biting midges, and possibly some mosquitoes, to pick it up and pass it to the next person.¹⁰ Whether Shamonda virus reaches comparable levels in human blood is unknown.

One more detail is worth noting. As of October 22, the same day the human case was announced, the French agriculture ministry’s page on the cattle outbreak still stated that the virus is not transmissible to humans and has no public health impact.⁷ The page is dated August 13.

The Infection Preventionist’s Takeaway

As of now, this remains an exceptional case in a single patient,and neither French authorities nor the ECDC have released genetic sequencing data.^1,2 While Shamonda virus is not an immediate threat to healthcare operations, this case is a stark reminder of how animal reservoirs and vector habitats overlap with vulnerable patient populations. For IPs, the lesson is not to overhaul daily protocols overnight, but to maintain a broad diagnostic curiosity when severe, unexplained viral complications emerge in immunocompromised hosts. As an IP, I will be following the sequencing updates closely to see whether this spillover was an isolated tragedy or a signal of shifting vector-host dynamics. I encourage colleagues to keep this case on their radar as the investigation continues to unfold.

References

1. Virus Shamonda: une première détection chez l’être humain [Shamonda virus: a first detection in a human]. Ministère de l’Agriculture, de l’Agro-alimentaire et de la Souveraineté alimentaire. October 22, 2026. Accessed October 22, 2026. https://agriculture.gouv.fr/virus-shamonda-une-premiere-detection-chez-letre-humain
2. Severely ill patient in France becomes first ever human infected with Shamonda virus. European Centre for Disease Prevention and Control. October 22, 2026. Accessed October 22, 2026. https://www.ecdc.europa.eu/en/news-events/severely-ill-patient-france-becomes-first-ever-human-infected-shamonda-virus
3. Ghebreyesus TA. France has reported the first documented case of a human infection with Shamonda virus. LinkedIn. October 22, 2026. Accessed October 22, 2026. https://lnkd.in/p/gM4Mqkgp
4. Rakaki ME, van der Walt M, Williams J, Venter M. Detection of novel orthobunyavirus reassortants in fatal neurologic case in horse and Culicoides biting midges, South Africa. Emerg Infect Dis. 2025;31(7):1455-1459. doi:10.3201/eid3107.241800
5. Kelleci M, Fusade-Boyer M, Chrétien D, et al. Detection of a novel Shamonda Orthobunyavirus in dairy cattle, France, June 2026. Euro Surveill. 2026;31(33):2600689. doi:10.2807/1560-7917.ES.2026.31.33.2600689
6. Hirashima Y, Kitahara S, Kato T, Shirafuji H, Tanaka S, Yanase T. Congenital malformations of calves infected with Shamonda virus, southern Japan. Emerg Infect Dis. 2017;23(6):993-996. doi:10.3201/eid2306.161946
7. Cas d’infections de vaches laitières par un orthobunyavirus [Cases of infection of dairy cows by an orthobunyavirus]. Ministère de l’Agriculture, de l’Agro-alimentaire et de la Souveraineté alimentaire. August 13, 2026. Accessed October 22, 2026. https://agriculture.gouv.fr/cas-dinfections-de-vaches-laitieres-par-un-orthobunyavirus
8. Shamonda virus in Switzerland. Institute of Virology and Immunology. August 25, 2026. Accessed October 22, 2026. https://www.ivi.admin.ch/en/neues-orthobunyavirus-der-simbu-serogruppe-bei-rindern-entdeckte
9. GDS France. Shamonda-Europe. August 21, 2026. Updated October 22, 2026. Accessed October 22, 2026. https://www.gdsfrance.org/shamonda-europe/
10. Increased Oropouche virus activity and associated risk to travelers. CDC. Health Alert Network. CDCHAN-00515. Published August 16, 2024. Accessed October 22, 2026. https://www.cdc.gov/han/2024/han00515.html
11. Clinical overview of Oropouche virus disease. CDC. Updated November 19, 2025. Accessed October 22, 2026. https://www.cdc.gov/oropouche/hcp/clinical-overview/index.html