New tick-borne virus discovered in China can affect the brain, scientists report

A new tick-borne virus discovered in China can spread to humans and sometimes cause neurological disease, scientists report.

The germ, dubbed Wetland virus (WELV), was first detected in a hospital patient who was treated in the city of Jinzhou in June 2019, according to a report published Wednesday (Sept. 4) in The New England Journal of Medicine.

The 61-year-old experienced fever, headache and vomiting approximately five days after visiting a park in a large wetland in Inner Mongolia, an autonomous region of northern China. He told doctors he'd been bitten by ticks at the park. Antibiotics didn't ease the man's symptoms, indicating that the infection wasn't caused by bacteria.

An analysis of DNA and RNA in the man's blood revealed a never-before-seen orthonairovirus — a group of related viruses that includes several carried by ticks. Other examples of these viruses include the one behind Crimean-Congo hemorrhagic fever, a rare and deadly illness that can spread to humans via tick bites or through exposure to infected people's bodily fluids.

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WELV had not previously been seen in animals or humans. After uncovering the virus in the hospital patient's blood, the researchers went looking for it in ticks and animals in northern China, including in the wetland park the man had visited.

They collected nearly 14,600 ticks and grouped them by location and species so they could be analyzed in batches. Roughly 2% of those batches tested positive for WELV genetic material. Five tick species could harbor the virus, but proportionally, ticks in the species Haemaphysalis concinna tested positive most often. The virus was also detected in a small percentage of the sheep, horses and pigs the researchers looked at, as well as in a handful of rodents called Transbaikal zokor (Myospalax psilurus).