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.
Related: Tick season: What to know about bites, removing ticks and tick-borne diseases 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.
Five tick species could harbor the virus, but proportionally, ticks in the species Haemaphysalis concinna tested positive most often.
The team also analyzed blood from “apparently healthy” forest rangers and found that 12 out of 640 samples carried antibodies against the virus.
In addition, they screened for the virus at four hospitals in northeastern China.
They tested for the virus in hundreds of patients who’d developed fevers within one month of a known tick bite, and 20 tested positive.
However, when the researchers tried injecting the virus into lab mice, they found that it could cause deadly infections, reaching many organs, including the brain.
“Taken together, these data suggest that a newly discovered orthonairovirus, WELV, is [pathogenic] to humans … and circulates among humans, ticks and various animals in northeastern China,” the researchers concluded.
Scientists report on the discovery of a novel tick-borne virus in China that can infect humans and occasionally result in neurological disorders.
According to a report released on Wednesday (Sept.), the virus, known as Wetland virus (WELV), was initially discovered in a hospital patient receiving treatment in Jinzhou in June 2019. New England Journal of Medicine, volume 4, page 4.
The sixty-one-year-old began experiencing fever, headaches, and vomiting about five days after going to a park located in a sizable marsh in Inner Mongolia, an autonomous region of northern China. He informed the medical professionals that ticks had bitten him in the park. Since the man’s symptoms did not improve with antibiotics, the infection was not bacterial in nature.
An examination of the man’s blood’s DNA and RNA revealed a previously undiscovered orthonairovirus, a family of related viruses that includes several tick-borne viruses. Additional instances of these viruses are those that cause Crimean-Congo hemorrhagic fever, an uncommon and fatal disease that can infect humans through tick bites or contact with bodily fluids from infected individuals.
Related: Tick season: A guide to tick removal, tick bites, and diseases carried by ticks.
Previously, neither humans nor animals had been observed to exhibit WELV. Once the virus was identified in the blood of the hospital patient, the researchers searched northern China for ticks and animals that could harbor the virus, including those that the man had visited in the wetland park.
To enable batch analysis, they gathered close to 14,600 ticks and classified them according to species and location. In those batches, about 2 percent of the samples had positive WELV genetic material tests. Although ticks from five different species may carry the virus, Haemaphysalis concinna ticks tested positive for the virus the most frequently. Along with a small number of rodents known as Transbaikal zokor (Myospalax psilurus), the virus was also found in a small percentage of the sheep, horses, and pigs that the researchers examined.
Although dogs and cattle did not contain genetic material from the virus, some of these animals did carry antibodies against the virus, suggesting that their immune systems had at some point developed a defense against the pathogen.
After examining blood samples from “apparently healthy” forest rangers, the researchers discovered that 12 out of 640 samples had antibodies against the virus. Furthermore, four hospitals in northeastern China were screened for the virus.
After a known tick bite, hundreds of patients experienced fevers; 20 of them tested positive for the virus. Of the 17, it appeared that only one was infected with WELV, while three had concurrent infections with other diseases spread by ticks.
Common symptoms for those infected with WELV included fever, headache, nausea, vomiting, diarrhea, and malaise in addition to back pain. Test findings showed that several of the patients had evidence of blood clotting and tissue damage.
Notably, a patient infected with WELV had entered a coma. The fluid surrounding that patient’s brain and spinal cord contained a high concentration of white blood cells, which is indicative of an infection. Thankfully, the researchers reported that “all the patients recovered and were discharged after 4 to 15 days” following treatment.
But after injecting the virus into lab mice, the researchers discovered that it could infect multiple organs, including the brain, and cause fatal infections. This result supports the theory that serious nervous system infections can be caused by WELV.
When considered collectively, the findings point to WELV—a recently identified orthonairovirus—as being [pathogenic] to humans and spreading throughout humans, ticks, and other animals in northeastern China. “A deeper comprehension of the impact that these viruses have on human health will be possible with improved surveillance and detection for emerging orthonairoviruses. ****.
