Scientists report that a new tick-borne virus has been discovered in China that can be transmitted to humans and sometimes cause neurological diseases. Animal studies have shown that the virus can cause fatal infections by affecting the brain and other organs. Infection with the orthonairovirus (Wetland virus – WELV) can cause serious neurological problems, as well as organ dysfunction, if not diagnosed and treated in time. This was reported to TASS by the press service of the National Medical Research Center for Phthisiopulmonology and Infectious Diseases (NMIC FPI) of the Russian Ministry of Health.
Earlier, the media reported that 17 people in northeastern China and several species of ticks and animals were found to have the Wetland virus (WELV). Rospotrebnadzor, in turn, reported that the situation is under the control of the agency, and the circulation of the virus in the Russian Federation has not been recorded.
“Symptoms usually appear a few days after a tick bite, and the disease can lead to more serious complications, such as organ dysfunction, if not diagnosed and treated in time. Mortality for humans has not yet been established, all infected recovered after treatment. However, WELV can cause serious neurological problems, which requires additional monitoring and diagnostics,” explained Maria Laseeva, an infectious disease specialist at the Center for General Infectious Pathology of the National Medical Research Center for Pedagogical Research of the Ministry of Health of Russia, whose words are quoted by the press service.
According to her, studies on animal models have shown that the virus can cause fatal infections, affecting the brain and other organs. As a treatment for patients infected with the virus, detoxification and symptomatic therapy are prescribed, which depends on the severity of the disease, Laseeva said.
The pathogen, dubbed wetland-element virus (WELV), was first identified in a hospital patient being treated in the city of Jinzhou in June 2019, according to a report published Sept. 4 in The New England Journal of Medicine.
The 61-year-old man developed fever, headache and vomiting about five days after visiting a park in a large wetland in Inner Mongolia, an autonomous region in northern China. He told doctors he had been bitten by ticks at the park. Antibiotics did not ease the man’s symptoms, suggesting the infection was not caused by bacteria.
DNA and RNA analysis of the man’s blood revealed a previously unseen orthonairovirus, a group of related viruses that includes several carried by ticks. Other examples of these viruses include the virus that causes Crimean-Congo hemorrhagic fever, a rare and fatal disease that can be transmitted to humans through tick bites or through contact with bodily fluids from infected people.
WELV had not previously been observed in animals or humans. After finding the virus in the blood of a hospital patient, researchers went looking for it in ticks and animals in northern China, including a wetland park the man had visited.
They collected about 14,600 ticks and grouped them by location and species so they could be analyzed in batches. About 2 percent of those batches tested positive for WELV genetic material. Five tick species could carry the virus, but Haemaphysalis concinna ticks were proportionally the most likely to test positive. The virus was also found in a small percentage of the sheep, horses, and pigs the researchers tested, as well as in a few rodents called the Transbaikal zokor (Myospalax psilurus).
The newly described virus is carried by ticks, pictured here, and can be transmitted to humans through tick bites. Bramborica, CC BY-SA 4.0
No genetic material from the virus was found in dogs or cattle, but some of these animals carried antibodies against the virus, suggesting that their immune systems had at some point developed protection against the germ.
The team also analyzed the blood of “apparently healthy” forest rangers and found that 12 of 640 samples contained antibodies to the virus. They also screened four hospitals in northeast China for the virus.
They tested hundreds of patients who developed a fever within a month of a known tick bite for the virus, and 20 tested positive. Three were simultaneously infected with other tick-borne diseases, while the other 17 appeared to have only WELV infection.
Patients with WELV infection experienced general symptoms such as fever, dizziness, headache, malaise and back pain, as well as nausea, vomiting and diarrhea. Laboratory test results showed signs of tissue damage and blood clotting in many patients.
Notably, one patient infected with WELV went into a coma. This patient had a high concentration of white blood cells, a sign of infection, in the fluid surrounding his brain and spinal cord. Fortunately, with treatment, “all patients recovered and were discharged within 4 to 15 days,” the researchers noted.
However, when the researchers tried to inject the virus into lab mice, they found that it could cause fatal infections, reaching many organs, including the brain. This finding supports the idea that WELV can cause serious infections of the nervous system.
“Taken together, these data suggest that a newly discovered orthonairovirus, WELV, is pathogenic to humans… and is circulating among humans, ticks, and various animals in northeast China,” the researchers concluded. “Improved surveillance and detection of new orthonairoviruses will provide a better understanding of the impact these viruses have on human health.”
