What is Enterovirus Infection?
Enterovirus infection is a group of acute infectious diseases caused by intestinal viruses (enteroviruses), characterized by fever and polymorphism of clinical symptoms caused by damage to the central nervous system, cardiovascular system, gastrointestinal tract, muscle system, lungs, liver, kidneys and other organs.
In recent years, there has been a clear trend in the intensification of enterovirus infection in the world, as evidenced by the constantly registered epidemiological ups and downbreaks in various countries. The geography of enterovirus infections is extremely wide and covers all countries of the world, including the post-Soviet space. So, in the scientific literature outbreaks of enteroviral (aseptic) meningitis in France (2002, 559 cases, ECHO viruses 13, 20, 6) are described, in Japan (2000, several hundred people fell ill, there were deaths, enterovirus 71- type), USA (2001, more than 100 cases, ECHO 13 virus), Spain (2000, 135 cases, ECHO 13 virus), Germany (2001, 70 people, Koksaki B5 virus), Turkey. The largest outbreaks described were in Taiwan (1998, 2000, about 3 thousand people fell ill, ECHO 13, 30, enterovirus type 71 prevailed) and in Singapore (2000, 1 thousand cases, 4 deaths, the outbreak was caused by enterovirus type 71), Tunisia (2003, 86 people, represented by ECHO viruses 6, 13). In the post-Soviet space, the largest outbreaks in recent years have been observed in Russia, in the Primorsky Territory (Khabarovsk, 1997, the viruses Koksaki B3, 4, 5, ECHO 6, 17, type 70 enterovirus prevailed) and in Kalmykia (2002 , 507 cases, ECHO virus 30), as well as in Ukraine (1998, 294 people fell ill, Koksaki B4 virus).
One of the main features of these infections is a healthy carriage of viruses, which constantly causes the occurrence of sporadic forms and mass diseases, which, like morbidity, is observed not only among young and older children, but also among adults. It was found that the length of stay of enteroviruses in the intestine does not exceed 5 months.
However, the main importance in maintaining the circulation of enteroviruses among the population, apparently, are two factors – the presence of susceptible contingents and the significant duration of the virus carrier. The latter feature allows the virus after infection of non-immune individuals, creating a highly immune layer, to wait for new susceptible contingents.
Causes of Enterovirus Infection
The modern classification of enteroviruses was developed in 2000 on the basis of data on the genetic structure and phylogenetic relationships of various representatives of the Enterovirus genus accumulated by this time. This genus includes the Picornoviridae family, which, in turn, includes 5 types of non-polio enteroviruses, namely Enterovirus A, B, C, D, E. Polioviruses in this classification constitute a separate species in the genus Enterovirus. Type A includes Coxsackie viruses A2–8, 10, 12, 14, 16 and enterovirus 71.
Species of Enterovirus B is the most numerous and includes all Coxsackie B and ECHO viruses, except ECHO 1, as well as Coxsackie A9 virus and enteroviruses of types 69, 73, 77, 78. The Enterovirus C species unites the remaining representatives of the Coxsackie A viruses, including types 1, 11, 13, 15, 17–22, and 24th. Species of Enterovirus D and E are relatively small and include 2 (Enterovirus68 and 70) and 1 (A2 plaque virus) representatives, respectively. In addition, the genus includes a significant number of unclassified enteroviruses. Thus, the genus Enterovirus includes more than 100 viruses dangerous to humans. They are ubiquitous and highly resistant to physical and chemical factors.