China has confirmed the first documented case of a severe human infection caused by the Oya virus, a pathogen belonging to the Orthobunyavirus genus that had previously been identified primarily in mosquitoes and biting midges. This case provides insight into the virus’s effects and how it can be transmitted to humans. The case is published in NEJM the 23 September 2026

The Oya virus is an arbovirus—meaning it circulates among animals and can be transmitted by insects.

It belongs to the Orthobunyavirus genus and was first identified in 2000. Since then, samples of the virus have been found in mosquitoes and biting midges across various parts of Asia, including China.

The new case involves a 54-year-old woman who worked at a goose farm in Qingyuan, in China’s Guangdong province.

The patient was admitted with fever, chills, and symptoms resembling sepsis. She subsequently developed severe vomiting, frequent diarrhea, and signs of bleeding.

Tests revealed a significant drop in platelet count, coagulation abnormalities, and liver damage. The virus was identified through genetic analysis of a blood sample.

How is the Oya virus transmitted?
The Oya virus is associated with blood-feeding insects. Previous research has detected the pathogen in mosquitoes and biting midges, including species of the Culicoides genus. Consequently, the transmission route currently under investigation is the bite of these insects.

This marks a significant difference from the coronavirus that caused the COVID-19 pandemic. The Oya virus does not behave like a respiratory virus transmitted directly between people.

To date, the discovery of this case does not prove the existence of sustained person-to-person transmission. Researchers are still studying its circulation, potential reservoirs, and the role insects play in its spread.

The documented case presented with high fever, vomiting, diarrhea, platelet abnormalities, coagulation issues, and significant liver damage. In laboratory experiments, the virus also caused damage to human liver tissue and severe illness in certain animal models.

Currently, there is no vaccine or specific antiviral treatment for the Oya virus. The Chinese patient received supportive care, made a good recovery, and was discharged after 19 days in the hospital.

The case demonstrates that the Oya virus can cause severe illness in humans, but further research is needed to determine how frequently this occurs, the actual level of risk, and how the virus circulates among insects, animals, and people.