Several new tick-borne viruses have been discovered in various parts of the world in the past 10 years. The latest may be a previously unknown orthonairovirus known as Wetland virus (WELV).

The virus was first identified in 2019 in a patient hospitalized with fever and multiple organ dysfunction in northeastern China after a visit to a wetland park in Inner Mongolia, researchers recently reported in the New England Journal of Medicine.

To further investigate WELV, the researchers tested 680 patients from 4 hospitals in northeastern China who'd developed a fever after being bitten by ticks. Twenty patients tested positive for WELV infection, and 3 of them also had other tick-borne diseases.

Most of the patients had nonspecific symptoms, including fevers, nausea, and vomiting. But 1 patient had neurological symptoms, including coma. In addition, mice injected with WELV showed pathological changes in their brains.

The researchers detected WELV in about 2% of 14 500 ticks collected from the region, identifying the Haemaphysalis concinna tick as a possible vector. They also found the virus in animals including mice, sheep, pigs, and horses. The presence of WELV in various animals may lead to easier transmission among ticks, and from there to humans, the researchers noted, adding that boosting surveillance and detection of the orthonairoviruses could lead to a better understanding of their effects on human health.