Experts at Hokkaido University are describing a previously unknown infectious disease that has emerged in Japan. Dubbed the “Yezo virus,” the novel virus is transmitted through tick bites and is characterized by fever and lowered levels of blood platelets and leukocytes.
“At least seven people have been infected with this new virus in Japan since 2014, but, so far, no deaths have been confirmed,” said virologist Keita Matsuno.
The Yezo virus was discovered in 2019 when a man was treated for fever and pain after a tick bite received while walking in a nearby forest. After being treated and discharged, hospital tests showed the man wasn’t infected by any known disease. Later the same year, a second patient was infected by the same disease.
It appears from genetic analysis that the disease is an orthonairovirus, a type of nairovirus and relative of the cCrimean-Congo hemorrhagic fever. After checking blood samples from hospital patients, the scientists have discovered that at least five people have been infected with Yezo virus since 2014.
While looking for the root of the Yezo virus, scientists discovered antibodies for the disease in raccoons and deer, suggesting they had previously been infected. The RNA from the virus was also found in three species of tick in the area, showing that the disease has established itself and is spreading in Hokkaido at least.
Scientists are concerned that it has likely spread beyond the island. During the current pandemic, it seems especially important to keep tabs on a newly discovered infectious disease.
“All of the cases of Yezo virus infection we know of so far did not turn into fatalities, but it’s very likely that the disease is found beyond Hokkaido, so we need to urgently investigate its spread,” said Matsuno.
The study is published in the journal Nature Communications.