Enteroviral infections are an extensive group of diseases caused by a special genus of viruses. The specificity and name of enteroviruses – “intestinal viruses” in translation – are due to the fact that the process of their reproduction proceeds most actively (or exclusively) in the gastrointestinal tract. Clinical manifestations, however, are far from being limited to the symptoms of enteritis; often there are no such symptoms at all.
Enteroviral infections today attract more and more attention of both researchers and the general non-medical community, due to a significant trend towards an increase in the incidence. It has not yet been possible to weaken or reverse this trend, and over the past decades, many epidemic outbreaks have been registered around the world, including in Russia, with the most severe forms in some cases ending in death. Asymptomatic carriage of enteroviruses in different regions of the globe varies from 20% to 40% of the healthy population. It is generally accepted that children predominate among those who fall ill with clinical forms of enterovirus infections, however, people of any age and gender, race and nationality, as well as places of residence are at risk of getting sick.
The reasons
The Enterovirus genus belongs to the Picornaviridae family. The last compound term is formed from the roots “pico-” (small, meaning – in comparison with other viruses) and “RNA” (i.e. RNA, a ribonucleic acid that transmits genetic information, one chain of which forms the basis of such a virus).
Enteroviruses, according to the latest classification, include 13 species, and many of their subtypes are pathogenic to humans. The Coxsackie and ECHO viruses have gained the greatest distribution and popularity in a variety of aggressive subtypes; the poliovirus that causes poliomyelitis in humans and higher primates also belongs to the same genus.
Enteroviruses are characterized by resistance to environmental conditions and the effects of a number of traditional antiseptics (alcohol, lysol, etc.), but they die at high temperatures, under the action of ultrasound and ultraviolet radiation, oxidizing agents, formalin, chlorine compounds.
Enteroviral infections are transmitted by airborne, contact-household, fecal-oral, food tracts, with appropriate risk factors. The likelihood of developing clinical symptoms (which occurs in about half of the cases) also increases with a weakened, for one reason or another, immunity. The virus carrier remains contagious for a long time, for several weeks or, in some cases, months. The incubation period between infection and the appearance of clinical symptoms (if any) is usually 3-7 days.
A person who has been ill develops immunity to this particular strain.
Symptoms
The clinical picture of enterovirus infections is extremely diverse – polymorphism ranges from latent and oligosymptomatic forms to severe, deadly meningitis, encephalitis, myo- and pericarditis, and hepatitis.
Typical, however, is the course of the ARVI type (enteroviruses are the second most common cause of acute respiratory viral infections), when general malaise with signs of intoxication, high fever, muscle and joint pain, “three-day fever”, etc. prevail. There are also purely intestinal forms (gastroenteritis), inflammatory processes in the organs of vision (conjunctivitis, uveitis), skin lesions (enteroviral exanthema), herpetic sore throat.
And yet, the greatest danger of enteroviruses is their pantropism, i.e. the ability to affect several body systems simultaneously. When involved in the acute inflammatory process of the central nervous system, myocardium, liver, pancreas, kidneys, the patient’s condition can be very severe, life-threatening (especially in immunodeficient individuals, newborns and representatives of other risk groups).
Diagnostics
A preliminary, and often a final clinical diagnosis is established based on the results of studying the anamnesis and epidemiological situation, characteristic symptoms and their dynamics, examination and observation of the patient. General clinical and biochemical laboratory tests are prescribed, if necessary, a puncture is performed with the selection of cerebrospinal fluid, instrumental diagnostic methods are used (ECG, EEG, tomography, ultrasound, etc.).
The identification of a specific subtype of enterovirus in the vast majority of cases is not necessary and is not carried out, since it requires a long and rather complex laboratory study.
Treatment
Preparations of etiopathogenetic therapy (targeting enteroviruses) are mainly under development or clinical trials. Interferons are used as prophylaxis, and immunoglobulins are used to stimulate the immune response. The rest of the treatment is palliative, symptomatic (detoxification, normalization of water and electrolyte balance, antipyretics, in more severe cases – hormonal anti-inflammatory drugs) and is determined by the characteristics of a particular case, up to intensive therapy and resuscitation.