A previously unknown virus that can infect humans and cause acute fever has been discovered in Japan. A new pathogen called Ezo virus is transmitted through tick bites. A description of the discovery was published in the journal Nature Communications.
From 2014 to 2020, seven patients had an unknown infection characterized by fever and a decrease in the number of platelets and leukocytes in the blood. There were no fatalities among them.
Researchers at the University of Hokkaido, along with colleagues from other universities and medical institutions in Japan, performed a genetic analysis of the virus isolated from blood samples from two patients from Hokkaido who were infected in 2019 and 2020 and determined that it was a new, previously unknown pathogen. Orthonairovirus, which also includes the Congo-Crimean hemorrhagic fever virus.
Scientists have named it the Jeso virus (YESV) after the ancient historical name of the island of Hokkaido. Phylogenetically, the new virus is similar to the Sulina and Tamara viruses found in Romania and Uzbekistan, respectively. The latter has recently caused several cases of acute fever in people in China.
It all started with the fact that in 2019, a 41-year-old man was hospitalized on the island of Hokkaido with fever and leg pain after being bitten by a tick. after a walk in the local forest. He was discharged two weeks later. Tests have shown that he is infected with an unknown virus. A second patient reported similar symptoms after a tick bite the following year.
The researchers then re-examined blood samples taken from hospital patients who had similar symptoms after tick bites since 2014, and found similar infections in tests of five more patients. All, including the first two, had a fever, decreased platelets and white blood cells, there were signs of liver dysfunction.
To determine the probable source of the virus, researchers tested samples collected from wildlife in the area between 2010 and 2020 and found antibodies to the new virus in spotted deer and raccoons and the virus’s own RNA in three major Hokkaido mites.
“The Jeso virus seems to spread to Hokkaido and cause disease when it is transmitted to humans from animals through ticks,” said study leader Kate Matsuno, a virologist at the International Zoonosis Control Institute, quoted in a press release from the University of Hokkaido. “None of the cases known to us have been fatal, but the disease is likely to be detected outside Hokkaido, so we urgently need to investigate its spread.”
In the next phase of the study, scientists plan to track the possible spread of the new virus among wild animals and humans across Japan. To do this, they want to gather information about patients who have been referred to hospitals in the country with similar symptoms.