The species of ticks, which are carriers of the new viral infection SFTS detected in China, lives in Russia and is common in the Far East. However, the virus itself has not yet been found in these arachnids in our country, virologist Mikhail Shchelkanov told Izvestia. The pathogen does not belong to respiratory infections, so it cannot get widespread. But the mortality rate from SFTS reaches 30%, which indicates its serious danger if detected.
Old New Huayangshan
China has recorded an outbreak of acute fever with thrombocytopenic syndrome caused by the Huaiyangshan virus. It is also referred to in the scientific literature as bunyavirus, dhabi bandavirus or SFTS virus. The abbreviation stands for severe fever with thrombocytopenia syndrome – severe fever with thrombocytopenic syndrome.
At the moment, China has recorded seven deaths among 60 infected, that is, the mortality rate is 11.6%. According to Taiwanese media reports, acute infectious diseases caused by tick bites have been reported since 2006 in the Chinese provinces of Henan, Hubei, Shandong, Anhui, Jiangsu, Zhejiang and others. Moreover, the outbreaks were characterized by a high mortality rate: from 15% to 30%. The virus was isolated in 2011 and then its active study began.
In particular, the pathogen has been found to be transmitted through the ixodid ticks Haemaphysalis longicornis. The laboratory of virologist Mikhail Shchelkanov is studying the distribution of these arachnids in Russia. In 1950-1960s, it was believed that these ticks live only in the extreme south of Primorsky Krai, the professor told Izvestia. However, thanks to field studies in his laboratory, it was possible to find out that the distribution of this species reaches at least the foothills of the Sikhote-Alin.
– These ticks live on the territory of our country, but we did not find a virus in them, – emphasized Mikhail Shchelkanov. – Maybe because they weren’t looking enough. To be sure of this, we need more extensive field research than those that my laboratory has the ability to conduct now on this topic. However, we have significantly clarified the range of ticks, and it turned out to be much wider than we thought at first.
In particular, employees of Shchelkanov’s laboratory found ticks of this species in wild boars. This expands the understanding of who can be the carrier of the virus and expands the geography of its spread in accordance with the migration routes of animals.
The ubiquitous parasites
The mites Haemaphysalis longicornis are found in a large number of animals. In the scientific article “On the issue of the northern border of the range and the owners of the tick Haemaphysalis longicornis in the Primorsky Territory ”, it is said that sika deer, cattle, horses, dogs, Himalayan bear, Amur forest cat, badgers and Asian chipmunks can be the feed for these arachnids. These ticks are also found in leopards.
And the SFTS virus itself is also multifaceted and omnivorous. An article by scientists at the Henan Center for Disease Control and Prevention (Zhengzhou, China) notes that the SFTS pathogen has a wide range of hosts. Antibodies to the virus have been found in goats and sheep, cattle, dogs and cats, chickens, rodents and pigs. The highest level of carriage of the virus genome was found in cattle, followed by cats, goats and rodents.
“However, there is no evidence that the virus can cause disease in animals,” the scientists write.
Also, there is no scientific evidence that mosquitoes and mosquitoes can transmit the pathogen, Mikhail Shchelkanov confirmed to Izvestia.
Symptom – thrombocytopenia
Symptoms of illness caused by the SFTS virus include fever, vomiting, diarrhea, thrombocytopenia (low platelet count), and leukopenia (low white blood cell count).
– When infected with the SFTS virus, a systemic inflammatory process develops, accompanied by damage to blood vessels and bone marrow, which leads to a drop in platelet levels and the development of hemorrhages., – explained to “Izvestia” associate professor of the Department of Infectious Diseases in Children of the PF RNIMU named after Pirogov Ivan Konovalov.
Thrombocytopenia is not dangerous in itself, it is simply the most characteristic symptom of this virus, added Alexander Lukashev, director of the Institute of Medical Parasitology, Tropical and Vector-borne Diseases of Sechenov University (the university is a participant in the 5-100 education competitiveness project).
“The virus itself threatens with systemic effects on various organs and the entire body,” the expert explained.
In particular, thrombocytopenia (a condition in which blood does not clot well) creates additional opportunities for the transmission of the virus. This explains the transition of the virus from person to person.
“Any doctor who comes into contact with the biological fluids of an infected patient, puts a tube down his throat by a surgeon or conducts an autopsy by a pathologist, naturally risks,” Mikhail Shchelkanov explained. – But this is called contact transmission. This virus is not respiratory; the spread of infection has a completely different epidemiological dynamics compared to acute respiratory diseases.
That is why Professor Shchelkanov believes that it is absolutely inappropriate to compare the SFTS virus with the causative agent of the current pandemic – SARS-CoV-2.
However, according to Alexander Lukashev, it is impossible to completely exclude the possibility of an outbreak of SFTS in Russia.
– As far as I know, this virus has not been found on the territory of the Russian Federation. But since cases of infection have been recorded in North China, Korea and Japan, and the pathogen is transmitted by tick bites, it is impossible to completely exclude the presence of both a carrier and a virus in the Far East.– said the scientist.
At the same time, the threat of the spread of SFTS in our country, according to Alexander Lukashev, can be assessed as low, since it is transmitted from person to person only with very close contact, for example, when caring for a sick person.