Eng / Enterovirus
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Enteroviral
infections
Associate Professor of the Department of Infectious Diseases
and Phthisiopulmonology
Blazhnaya L.P.
Enteroviral infections
A large group of anthroponotic infectious diseases with a fecal-oral mechanism of infection caused by enteroviruses of the Coxsackie group and ECHO, characterized by a polymorphism of the clinical picture
(damage to the central nervous system, muscles, mucous membranes and skin).
Etiology
Viruses of this group (intestinal viruses) belong to enteroviruses, families Picornoviridae are tropic
to the muscle
epithelial,
nervous tissue, which in some cases causes complications associated with damage to the membranes of the brain, heart muscle, liver.
Сlassification of enteroviruses
1.Polioviruses - serotypes 1-3
2.non-polio human enteroviruses:
Coxsackievirus group A Group B coxsackieviruses Echoviruses (ECHO)
According to the latest classification of viruses (2003), based on genomic characteristics, non-polio human enteroviruses are represented by 4 species (A, B, C, D)
Enteroviruses - RNA-
containing viruses
They are stable in the external
environment, but are inactivated
at temperatures above 50°C
(at 60°C in 6-8 minutes, at 100°C –
instantly).
At a temperature of 37°C, they can be stored for 50-65 days.
Viruses survive for a long time in water (in tap water - 18 days, in river water - 33 days, in waste water - 65 days).
They die under the influence of ultraviolet radiation and when dried.
Solutions of iodine, 0.3% formaldehyde, 0.1 N HCl or chlorine at a concentration of 0.3-0.5 mg / l quickly destroy viruses
Epidemiology
Enteroviruses in nature exist due to two reservoirs:
natural (soil, water, food)
and the human body, in which they can accumulate and through which, respectively, spread.
The main epidemiological feature of the infection is the ability of a person to form the so-called. "Healthy virus carrier" with a longterm, up to several weeks, release of the pathogen into the external environment.
Infection with enteroviruses occurs throughout the year, but a significant increase in the incidence occurs in the summer and autumn months.
in the tropics, the infection is recorded all year round.
Approximately 75% of EVI reported annually by WHO are in children under 15 years of age. Children under 1 year old are sick several times more often than older children and adults [
For unknown reasons, males are at greater risk of EVD.
The main mechanism of transmission of infection
— fecal-oral, realized by food, water and contact household routes.
Less commonly, the infection is transmitted by airborne droplets and transplacental (from mother to fetus).
droplet introduction of the virus into the respiratory tract is accompanied by the subsequent evacuation of the pathogen into the oropharynx, where, after ingestion, it enters its ecological niche - the intestines, followed by the development of the infectious process.
Epidemiology
Direct contact with infected faeces occurs when babies are swaddled. Therefore, infants are the most "effective" transmitters of infection. In 1 g of feces up to 107-108 viruses
An important route of spread is contact with infected objects and the hands of another person, followed by inoculation of the virus through the mouth, nose, or eyes.
Cases of infection are described when swimming in sea water polluted by sewage.
Infected individuals are most contagious in the first week of illness.
Every 3-4 years there are epidemic outbreaks of the disease caused by various virus serotypes.
PATHOGENESIS
Getting on the mucous membranes of the nasopharynx, the Coxsackie virus penetrates the intestines and lymph nodes, where it multiplies intensively.
On the third day of illness, a critical amount of viruses is in the blood.
This greatly facilitates their access to the nervous and muscle tissue, which determines the general serious condition of the patient.
In the study of individual muscle fibers affected by the Coxsackie virus, dystrophic changes and necrosis were revealed. Studies of the affected meninges (with concomitant serous meningitis) revealed pronounced edema and hemorrhages.
Clinical classification
Clinical forms Typical Clinical forms Atypical