What viruses are chronic. Symptoms and treatments for viral infections in children and adults

The human species constantly interacts with wildlife. Today, the opinions of world scientists are unanimous - viruses appeared long before the formation of the DNA molecule. There is a hypothesis that a bacterium is the evolutionary result of degenerative unicellular organisms, a kind of descendant of an ancient pre-cellular life form. The annual struggle of mankind with unknown types of viruses leads to reasonable conclusions - they mutate, develop and adapt to the conditions we create, while actively participating in the evolutionary formation of the genetic material of all living organisms. Every year, massive pandemics claim hundreds of lives.
We present you the top 10 most dangerous viruses known to man not only from ancient times.

Human Immunodeficiency Virus (AIDS)

The deadly virus rightfully takes first place in the world ranking. To date, there is no cure for AIDS. It is possible to protect yourself from infection only with the help of effective prevention.
The first cases of AIDS were recorded in the 1930s in a West African country. Then it was believed that the carrier of the virus were monkeys. The official isolation and laboratory study of the pathogen was carried out in 1980 with the identification of 440 US carriers.
The causative agent, the human immunodeficiency virus, destroys the defense system by damaging CD4-lymphocytes (cells responsible for the destruction of pathogenic infection), a decrease in the number of which leads to a decrease in the body's resistance to the surrounding pathogenic microflora.
The source of infection is a latent carrier or a sick person. Infection occurs through blood and biological secretions - sexual contact of all kinds, blood transfusion, childbirth, breastfeeding, injections, organ transplants, household microtraumas.
The incubation period is long, from the moment the pathogen enters the body to the onset of symptoms, a lot of time passes - from a year or more.

The average life expectancy of an HIV-infected person is no more than 11-15 years.

Known stages of HIV

Feverish - appears in 50% of those infected, is characterized by minor intestinal or cold symptoms (body aches, diarrhea, nausea, rarely a rash and sore throat);
asymptomatic - duration up to 10 years. The virus destroys the immune defense. Very rarely, small swellings appear in the area of ​​the lymph nodes;
development of AIDS. Activation of latent pathogenic organisms living in the human body. The appearance of a white coating on the tongue, hemorrhagic eruptions of the extremities, sweating, decreased vision, a sharp weight loss of up to 10% of the total mass. Then the condition is aggravated by hyperthermia, diarrhea, lymphoma, tuberculosis and Kaposi's sarcoma.
The life expectancy of an HIV patient with progressive symptoms is no more than two years.
Treatment of HIV is carried out with immunostimulating, antiviral and antibacterial drugs in stationary conditions. The main goal of drug therapy is to prolong the life of an infected person.

Fundamental Methods for Effective HIV Prevention

1. Use of a condom, one sexual partner.
2. Do not use other people's hygiene items.
3. For medical manipulations, the use of a disposable instrument.

Rabies virus

A very dangerous virus in the world for humans. The disease has been known since ancient times. An effective method of combating the disease is timely and urgent revaccination immediately after infection. The countries of Asia, Africa, Canada, the USA are most vulnerable to infection (the first cases of human infection since 1880).
The causative agent, the Rabies virus, is transmitted through a bite, ingestion of the saliva of a domestic or wild animal into the bloodstream. Having entered the body, the virus destroys the central nervous system, causing meningoencephalitis, asphyxia and cardiac arrest due to paralysis of the respiratory tract.

The source is an infected animal - a dog, a cat, a fox, a raccoon, rodents. Infection by a pet of a person is possible even during the incubation period.
The process of disease development lasts from 10 days to a year in humans (usually 1-4 months), animals - up to 2-3 weeks. If not vaccinated within the first 10 days after being bitten, there is a 99% chance of death in humans (only 3 cases of recovery after the active phase are known worldwide).

Symptoms of rabies

Symptoms of the progress of the disease are characterized by periods:

1. Early - subfebrile body temperature, anxiety (1-3 days).
2. Razgar - aggression, hallucinations, delirium, fear of water (up to 4 days).
3. Paralytic - the state of a living corpse, indifference, lack of reactions, paralysis of the limbs, suffocation (up to 8 days).
Treatment of the patient during the period of active symptoms is not effective - medical supervision is limited to symptomatic measures to alleviate the condition of the infected person.

Rabies preventive measures taken

Timely vaccination of pets;
seek immediate medical attention if bitten by stray dogs, cats or wild animals;
passing a full course of conservative therapy immediately after the bite.

Ebola virus (hemorrhagic fever)

This is the name of a dangerous, highly contagious virus for humans, the causative agent of which is the filovirus Zaire ebolavirus. First identified in 1976, during an epidemic in Zaire that covered most of the Ebola basin (nearly 90% death).
It has been established that the carriers of the virus are rodents, bats and monkeys.
Subsequent epidemics are caused by mutational virion species:
Nzara town and Uganda (Sudan). In 1976, the death rate from this virus was 54%, in 1979 - 53%, in 2000 - 53% of cases. The source of infection has not been identified;
Philippines, then USA. 1989 - outbreak of hemorrhagic fever among monkeys;
Tai forest (Africa). 1994 - human infection through laboratory studies of the corpses of monkeys;
Bundibugyo (Uganda). 2007 - the epidemic claimed 40 human lives out of 140 registered cases of the disease;
Congo. 2012 - 37% mortality.
Currently, the Ebola vaccine is being tested in monkeys, so there is no information about the next arrival of the antiserum on the consumer market. The Ministry of Health officially confirmed the admission of experimental serum to prevent the popularization of epidemics.
The disease is characterized by seasonal outbreaks and is recognized as a global threat to humanity.
Localization of the pathogen mainly in the blood, saliva, other secretions and fluids of the infected (sperm, urine, mucus). Transmitted by contact, injection, sexual contact. Infection is not excluded by shaking hands and using common household items.
The period of development of the disease covers 2-3 weeks. Once in the body, the virus blocks the complementary blood group (inactive proenzymes that bind to antigenic bodies to destroy and agglutinate the latter).
The main signs of Ebola fever are hemorrhagic rashes, fatigue, apathy, pain in the spine and extremities, pharyngitis, and a sharp increase in temperature. Then comes diarrhea, abdominal pain, disorientation. A week later, the active phase is replaced by increased pain, nosebleeds, bloody diarrhea, dry cough and acute pancreatitis. On the 14th day of illness - infectious intoxication, hemorrhagic shock, massive blood loss.
Plasma of convalescents (carriers who acquire immunity after illness) has a positive trend in the treatment of a patient with Ebola. However, the method does not guarantee a complete recovery. The total death rate from the Ebola virus is about 50%.

Marburg virus (hemorrhagic fever)

A close relative of Ebola hemorrhagic fever. 1967 is the date of the first human infection with this virus, recorded in Marburg (Germany). The source of infection was monkeys from Uganda, brought for experiments.
The causative agent of the disease is the Filoviridae virus of zoonotic origin (transmitted to humans from animals). It is assumed that infection occurs through contact with biological fluid (saliva, vomit, blood, secretions).
Risk group for potential Marburg virus infection
veterinarians in contact with monkeys from Africa;
scientists studying the virus;
healthcare workers in contact with a sick Marburg virus;
laboratory staff involved in the study of biomaterial.
The period of development of fever (incubation) lasts no more than 10 days. Then the patient feels fever, muscle pain. Gradually, the symptoms worsen - rashes appear on the body, diarrhea, abdominal pain, jaundice, pancreatitis, organic dysfunction, weight loss. Further development of liver failure, internal blood loss, delirium and hallucinations is not excluded. The mortality rate ranges from 25 to 85%.

There is no vaccine against Marburg virus.

The study of contagiousness and the development of serum began in 2014. Today, the world knows nanoparticles that have the ability of viral dereplication, tested on monkeys.
According to scientists, the only way to protect against the virus is to use maximum precautions when in contact with African animals.

Smallpox virus (natural)

The variola virus, which is dangerous to humans, is divided into two types: Variola Minor (chickenpox) and Magor (black pox). Epidemics of smallpox claim from 40% to 90% of human lives, the survivors become visually impaired.
The first mention of a deadly disease in the 4th century is an epidemic of smallpox in China (95% mortality). VI century - the disease affects densely populated areas of Korea (88% of deaths). 737 - Japan's population decline by 35% (pandemic of smallpox). Smallpox has claimed millions of European lives since the 1500s. Between 1700 and 1800, the first smallpox serum was made and tested. Variolation (grafting) had the effect of reducing mortality by up to 10%.
Infection occurs by airborne droplets, upon contact with a carrier or a patient. The incubation period does not exceed two weeks. Entering the lymph, the virus spreads through the epithelium, forming purulent pustules. Severe forms of the disease develop hemorrhagic syndrome, encephalitis, toxic shock and death. A cured person gets ugly scars from pustules all over the body. As a consequence of extensive hemorrhoidal hemorrhages, the survivors become blind.
A person is contagious to others from the last five days of incubation until the crusts of pustules fall off.

The body of a person who died of smallpox is contagious for up to four months.

Spanish influenza (Spanish flu) or influenza virus

The most dangerous virus in the world. During the First World War, more than 35% of the world's population was infected with the Spanish flu, of which the mortality rate was about 5% of the total number (150 million people).
The causative agent is the H1N1 virus, isolated during the study of a mummy in Alaska (XVIII-XIX centuries). It is transmitted by airborne droplets. After a certain incubation time (up to 4 days), the patient develops cyanosis of the skin, a sharp increase in body temperature up to 40 degrees, coughing up blood. Then lightning-fast development of pulmonary hemorrhage. Death comes from choking on one's own blood.
The development of severe complications with a fatal outcome in the first days of the disease was observed mainly in patients with reduced immunity, during pregnancy, in children under 14 years of age, and in the elderly.

Signs of infection

Characteristic signs of infection for patients at risk
1. The rapid development of hemorrhagic pneumonia (in a few hours).
2. The disease affects only adults (from 25 to 45 years old).
3. The probability of death is 95% on the first day of the disease.

The massive Spanish flu pandemic during the First World War is recognized as a global catastrophe of a large-scale nature.

In subsequent years, active vaccination of the population was carried out, infected patients were treated with antiviral drugs.
To date, the H1N1 virus has been modified and has a milder course. When outbreaks of Spanish flu are detected, the lethal outcome is no more than 2% (mainly among patients who applied for medical help late).

Dengue virus (bone-breaking fever or date disease)

A dangerous virus that is transmitted transmissibly (through the bites of blood-sucking insects). Places of localization - in the countries of South and East Asia, Africa, the Caribbean. The annual incidence is about 50 million people, with a hemorrhagic form, the death rate is up to 50%.
In the middle of the 20th century, the Flavivirus virion was isolated as the causative agent of the Dengue virus (the Flaviviridae family of abroviruses - antigenic group B).
The source of infection are monkeys, a sick patient, rarely bats. The disease is believed to be carried by mosquitoes. The insect is contagious for the first three months after the bite of an infected individual and can be a carrier of several virus serotypes at once. The period of development of the virus in the human body is up to seven days.
The main symptoms of the mild stage (primary infection - classic)
muscle and bone pain;
temperature increase up to 40 degrees;
heartbeat;
hyperemia of the eyeballs, throat;
rashes on the body, itching;
anxiety.
A more severe form of the disease develops in the local population, and occurs when a single infection with several varieties of abrovirus.
Symptoms of the hemorrhagic form of the disease
increased lymph, nausea, vomiting;
cough, weakness, abdominal pain;
development of pancreatitis, gastric bleeding;
cyanosis;
heart palpitations, vomiting blood.
Dengue fever is treated with painkillers and vitamins. In severe forms, plasma therapy, coagulants, glucocorticoids are used.

Secondary infection with the Dengue virus is more dangerous for a person than the primary one, since the body's production of antibodies and the acquisition of immunity only exacerbate the course of a recurrent disease.

Zika virus (Zika fever)

One of the varieties of dangerous viruses transmitted transmissibly. Laboratory isolated from the monkeys of the Zeke forest (Uganda) in 1947. The first human infection was recorded in 1968 (Nigeria). From 1951 to 1982, serological cultures of the virus were found in India and Egypt. Since 2007, there has been an eastern popularization of the virus - New Caledonia, Easter and Cook Islands, South and Central America, Africa. In 2007, the disease was given pandemic status.
The causative agent is the Flavivirus virus, which causes the same type of disease. Monkeys are the source of infection. The infection is transmitted with the help of blood-sucking insects; transmission through blood, natural secretions, and sexual contact is also not excluded.
The incubation period lasts no more than two weeks. The first signs of the disease are rashes on the body, fever, aches, pain in the joints, swelling of the limbs. There are no signs of severe intoxication.
In the modern world, there are no specific drugs for the treatment of a viral infection yet. The disease is not fatal, but it has a pronounced degree of neurotropism (affects nerve and neural stem cells). As a complication, it causes microcephaly.

Lassa virus (Lassa fever)

The infection is characterized by a severe course, damage to the respiratory organs, hemorrhagic consequences, and a high percentage of death.
The causative agent is the Lassa mammarenavirus virus, officially recognized as one of the most dangerous to humans. The source of infection are rats. The main localization is Western and Central Africa. The mechanism of transmission of the virus to humans is mainly fecal-oral (through food, water), aerosol and direct contact.
A patient with Lassa fever is very contagious to others. Infection from a person occurs through blood, natural secretions, in a contact manner. Cases of viral infection of medical staff through the instruments used are known.
The period of development of the disease lasts from six days to two to three weeks. The patient feels general malaise, fever, muscle pain. Gradually appear lesions of the mucous eyes (conjunctivitis), an increase in lymph. In 80% of patients, manifestations of ulcerative necrotic pharyngitis of the throat are noted; fever is accompanied by diarrhea, vomiting. The second week of the disease is characterized by a rash, hemorrhagic bleeding (nasal, uterine, subcutaneous, pulmonary). A severe course is marked by swelling of the face and the rapid development of blood loss, general intoxication. Death is highly likely within 10-12 days of illness.
Treatment of patients with Lassa fever is carried out using antiviral drugs, antibiotics, and plasma administration is practiced in the early stages. In severe stages of the disease, mortality reaches 55%.
Protective preventive measures against infection with the Lassa virus include disinfection of premises, quarantine measures for those arriving from localization countries.

Rotavirus (intestinal flu)

Due to the presence of a 40% death rate, the disease caused is considered life-threatening. Children under the age of five are at particular risk of infection.
The causative agent of the disease is the Reoviridae virus isolated in 1943. Once in the body, it causes severe dehydration, followed by intoxication. The occurrence and development of the disease is seasonal - the virus is activated in the winter.
Focal cases of the disease are most often recorded in nursing homes and preschool institutions. The most famous outbreak of rotavirus infection was recorded in 2005 (Nicaragua - 30% mortality). According to studies, it is assumed that the focus of development of rotavirus arose due to a mutation of the virus. Previously, another outbreak of focal infection in Brazil (1977) is known.
The origin of the virus is not known. A person can become infected by drinking dirty water, through household appliances, or through close contact with an infected carrier. The period of development of symptoms of malaise is up to five days.

Symptoms of rotavirus infection

1. Primary - against the background of weakness and loss of strength, an increase in temperature to 40 degrees, vomiting, the appearance of a light yellow clay-like stool.
2. Secondary - signs of dehydration (fluid loss) are aggravated, against the background of vomiting and frequent liquid defecation, there is no appetite, a runny nose and sore throat, dark urine.
The treatment is carried out in a complex way - simultaneous relief of dehydration symptoms, reduction of intoxication of the body, intravenous fluid administration.
As a prophylactic against rotavirus infection, it is used in countries with an insufficient level of medical care and severe signs of unsanitary conditions.

The ranking of the top 10 dangerous viruses on the planet is not final. Which of them is the most dangerous is also impossible to predict. Every day, scientists discover new types of viruses, investigate their origin and nature, and try to understand how safe they are for human existence.
However, despite the high scientific achievements, the problem of human resistance to viruses remains relevant to this day. To save our population, it is necessary to constantly actively resist destructive viral diseases. Therefore, it is very important to know the etiology of the most aggressive, but already familiar to mankind, biological microorganisms.

Viruses live while they fight and die from inactivity. They are very fastidious about food, they live "on loan" at the expense of animal cells, plants and even bacteria. Viruses bring mostly harm and very rarely benefit, so to speak, benefit through harm. The kingdom of viruses was discovered relatively recently: 100 years ago. In 1892, the Russian scientist D.I. Ivanovsky described the unusual properties of the causative agents of tobacco disease - (tobacco mosaic), which passed through bacterial filters.

For details about viruses, what they are, how they develop, how they harm a person and what consequences they can lead to, see the video recording from Pavlusenko I.I.:

A few years later, F. Leffler and P. Frosch found that the causative agent of foot-and-mouth disease (a disease of livestock) also passes through bacterial filters. And in 1917, F. d'Errell opened bacteriophage - virus that kills bacteria. So the viruses of plants, animals and microorganisms were discovered.

These three events marked the beginning of a new science - virology, which studies non-cellular life forms.

Viruses very small, they cannot be seen, however, today they are one of the most studied objects, as they cause some of the most frequent and dangerous human diseases and not only.

It is now recognized that viruses are the causative agents of cancer, leukemia and other malignant tumors. Therefore, the solution of the problems of oncology now depends on the knowledge of the nature of cancer pathogens and the mechanisms of carcinogenic (tumor-causing) transformations of normal cells.

Viruses are everywhere where there is life. From the moment of our birth, they accompany us every second of life.

Most of the known diseases in medicine are caused by viruses. But they also infect animals, plants, and even bacteria. This fact makes it clear that the protection against viruses and their destruction is the main task of medicine and humanity.

Viruses are transmitted:

• through insects and mites
• through the plants in which they are implanted
• through people: coughing or sneezing;
• by contact with contaminated food
• fecal-oral route
• sexually
• transfusion of contaminated blood

Infection occurs by introducing the virus into the cell. Most often, such a cell dies under the influence of the proteins of the virus, but sometimes it mutates and begins to behave randomly. Different viruses behave differently and cause a variety of diseases.

The most common human viral diseases:

• colds, flu, acute respiratory syndrome;
• , trophic fever;
• , Epstein-Barr virus, infectious mononucleosis;
• , shingles;
• AIDS;
• oncoviruses can lead to cancer of the skin, liver, cervix, penis, and leukemia. Some viruses can lead to different types of lymphoma and carcinoma. Read the article on.

It is impossible to name any specific symptoms of viral diseases person, because if you look at the list of diseases, it is easy to understand that they will have completely different symptoms. Although a common symptom can still be - lethargy, irritability, fatigue. This is enough to immediately begin prevention, even if it's just a cold.

Prevention and treatment of viral diseases

Against some viruses, we are given vaccines in infancy, which create immunity to infections. Having been ill with some diseases in childhood, we also become immune to other diseases.

There are people who live their whole lives and practically do not get sick. And there are those who get sick at the slightest contact with these little creatures. It says only one thing, that your .

Be healthy!

There is an opinion that animals, plants and humans predominate on planet Earth. But this is not really the case. There are countless microorganisms (germs) in the world. And viruses are among the most dangerous. They can cause various diseases in humans and animals. Below is a list of the ten most dangerous biological viruses to humans.

Hantaviruses are a genus of viruses transmitted to humans through contact with rodents or their waste products. Hantaviruses cause various diseases related to such groups of diseases as "hemorrhagic fever with renal syndrome" (average mortality 12%) and "hantavirus cardiopulmonary syndrome" (mortality up to 36%). The first major outbreak caused by hantaviruses, known as "Korean hemorrhagic fever", occurred during the Korean War (1950–1953). Then more than 3,000 American and Korean soldiers felt the effects of a virus unknown at the time, which caused internal bleeding and impaired kidney function. Interestingly, it is this virus that is considered the likely cause of the epidemic in the 16th century, which exterminated the Aztec people.

The influenza virus is a virus that causes an acute respiratory infection in humans. Currently, there are more than 2 thousand of its variants, classified according to three serotypes A, B, C. The group of the virus from serotype A divided into strains (H1N1, H2N2, H3N2, etc.) is the most dangerous for humans and can lead to epidemics and pandemics. Every year, from 250 to 500 thousand people die from seasonal influenza epidemics in the world (most of them are children under 2 years old and elderly people over 65 years old).

The Marburg virus is a dangerous human virus first described in 1967 during small outbreaks in the German cities of Marburg and Frankfurt. In humans, it causes Marburg hemorrhagic fever (mortality 23-50%), which is transmitted through blood, feces, saliva and vomit. The natural reservoir for this virus is sick people, probably rodents and some species of monkeys. Symptoms in the early stages include fever, headache, and muscle pain. In the later stages, jaundice, pancreatitis, weight loss, delirium and neuropsychiatric symptoms, bleeding, hypovolemic shock, and multiple organ failure, most often the liver. Marburg fever is one of the ten deadliest animal-borne diseases.

The sixth most dangerous human virus is Rotavirus, a group of viruses that are the most common cause of acute diarrhea in infants and young children. Transmitted by the fecal-oral route. The disease is usually easily treated, but more than 450,000 children under the age of five die each year worldwide, most of them in underdeveloped countries.

The Ebola virus is a genus of viruses that causes Ebola hemorrhagic fever. It was first discovered in 1976 during an outbreak in the Ebola River basin (hence the name of the virus) in Zaire, DR Congo. It is transmitted through direct contact with the blood, secretions, other fluids, and organs of an infected person. Ebola is characterized by a sudden increase in body temperature, severe general weakness, muscle and headaches, and sore throat. It is often accompanied by vomiting, diarrhea, rash, impaired kidney and liver function, and in some cases internal and external bleeding. According to the US Centers for Disease Control, in 2015, 30,939 people were infected with Ebola, of which 12,910 (42%) died.

Dengue virus is one of the most dangerous biological viruses for humans, causing dengue fever, in severe cases, with a mortality rate of about 50%. The disease is characterized by fever, intoxication, myalgia, arthralgia, rash, and swollen lymph nodes. It occurs mainly in the countries of South and Southeast Asia, Africa, Oceania and the Caribbean, where about 50 million people are infected annually. The carriers of the virus are sick people, monkeys, mosquitoes and bats.

The smallpox virus is a complex virus, the causative agent of a highly contagious disease of the same name that affects only humans. This is one of the oldest diseases, the symptoms of which are chills, pain in the sacrum and lower back, a rapid increase in body temperature, dizziness, headache, and vomiting. On the second day, a rash appears, which eventually turns into purulent vesicles. In the 20th century, this virus claimed the lives of 300–500 million people. The smallpox campaign spent about US$298 million between 1967 and 1979 (equivalent to US$1.2 billion in 2010). Fortunately, the last known case of infection was reported on October 26, 1977 in the Somali city of Marka.

The rabies virus is a dangerous virus that causes rabies in humans and warm-blooded animals, in which a specific lesion of the central nervous system occurs. This disease is transmitted through saliva when bitten by an infected animal. Accompanied by an increase in temperature to 37.2-37.3, poor sleep, patients become aggressive, violent, hallucinations, delirium, fear appear, paralysis of the eye muscles, lower extremities, paralytic respiratory disorders and death soon occur. The first signs of the disease appear late, when destructive processes have already occurred in the brain (edema, hemorrhage, degradation of nerve cells), which makes treatment almost impossible. To date, only three cases of human recovery without vaccination have been recorded, all the rest ended in death.

Lassa virus is a deadly virus that causes Lassa fever in humans and primates. The disease was first discovered in 1969 in the Nigerian city of Lassa. It is characterized by a severe course, damage to the respiratory organs, kidneys, central nervous system, myocarditis and hemorrhagic syndrome. It occurs mainly in West African countries, especially in Sierra Leone, the Republic of Guinea, Nigeria and Liberia, where the annual incidence ranges from 300,000 to 500,000 cases, of which 5 thousand leads to the death of the patient. The natural reservoir of Lassa fever is the multi-nipple rat.

The human immunodeficiency virus (HIV) is the most dangerous human virus, the causative agent of HIV infection / AIDS, which is transmitted through direct contact of the mucous membranes or blood with a bodily fluid of the patient. In the course of HIV infection in the same person, all new strains (varieties) of the virus are formed, which are mutants, completely different in reproduction speed, capable of initiating and killing certain types of cells. Without medical intervention, the average life expectancy of a person infected with the immunodeficiency virus is 9–11 years. According to 2011 data, 60 million people have become ill with HIV infection in the world, of which: 25 million have died, and 35 million continue to live with the virus.

Viral infections are diseases caused by pathogenic tiny particles called viruses. Their important feature is the presence of severe complications, especially in children and the elderly. Despite the variety of clinical forms, approaches to the diagnosis and treatment of most viral diseases are of the same type. Immunoprophylaxis and timely vaccination play an important role for the health of the population.

Causes of viral infectious diseases

The causes of infectious diseases can be divided into two large groups. On the one hand, these are the internal factors of the human body that create good conditions for the introduction and reproduction of the virus. This includes a decrease in local immunity, hypovitaminosis, chronic somatic diseases (primarily diabetes and liver disease).

In children, the anatomical features of the respiratory system play an important role: narrow nasal passages, immaturity of the pharyngeal lymphoid ring, small size of the larynx, abundant blood supply to the respiratory tract. In addition, babies between the ages of 2 and 5 have intense contact with other children and adults, which leads to an increased risk of infection.

On the part of pathogens, it is important to note their ability to mutate. Viruses intensively change the genetic material, acquiring new properties and mastering new ways of transmission. This allows them to successfully circulate in the environment and retain the ability to survive in the human body.

Classification

All causative agents of viral infectious diseases are the smallest particles-virions. For practical purposes, it is most important to know the path and mechanism of their distribution. On this basis, viral infections are divided into:

• Airborne infections of the respiratory tract (influenza, parainfluenza, adenovirus infection, measles, rubella, chicken pox).
• Intestinal (rotavirus infection, disease caused by Coxsackie and ECHO viruses, hepatitis A and E, etc.).
• Blood (hepatitis B, C, D, HIV, etc.).
• Contact (herpes of the first and second types, HPV, etc.).

Flu

Causative agent: influenza virus. It has strains A, B and C. Strain A is the most common in nature. It has a tendency to mutate , and this explains the high incidence of influenza among the population. The virus is unstable in the external environment, does not tolerate drying, sharp fluctuations in ambient temperature. Dies when exposed to conventional detergents, ultraviolet radiation.

The source of infection is a sick person from the end of the incubation period. The sick person is most contagious during catarrhal phenomena (runny nose, cough). The path of spread of the pathogen: airborne. Incubation period: from 15 hours to 3 days, on average 24 hours.

Clinical picture: a distinctive feature is that the phenomena of general intoxication always come to the fore. The disease begins with a sudden rise in temperature to 38.5-39 ° C. There is a headache, a feeling of "ache" in the joints and muscles. Only by the end of the first day catarrhal symptoms join: dry cough with scanty sputum, runny nose. On the 3rd-4th day of illness, the cough becomes wet, sputum comes out intensively. The disease lasts an average of 5-7 days.

Features in children: in older children, symptoms of CNS damage can often appear - photophobia, tension of the occipital muscles, grimace of pain on the face.

In newborns and infants with influenza, fever and severe intoxication are rarely detected, catarrhal phenomena (rough cough, nasal congestion) are mild. The severity is determined by the frequent development of bacterial complications in the child, such as pneumonia, pulmonary edema, meningitis, etc.

Treatment and prevention: Oseltamivir, Remantadine, Amantadine, interferon preparations (Grippferon, Anaferon). Symptomatic treatment: NSAIDs (ibuprofen, etc.), nasal vasoconstrictors, antitussives (Codelac, Tusuprex, Terpinkod) and expectorants (Mukaltin, ACC, Ambrobene). For bacterial infections, antibiotics are used in accordance with the sensitivity of the pathogen. Prevention: immunization of the population before the expected epidemic season.

parainfluenza

Causative agent: parainfluenza virus. In humans, the disease is caused by four types of virus (1, 2, 3, 4). The virus is unstable in the environment. At room temperature, it dies after 4 hours. It is sensitive to disinfectants. The source of the pathogen is patients with typical and erased forms of the disease, contagious for a week. Way of distribution: airborne. Susceptibility is high. Incubation period: from 1 to 7 days, on average 5 days.

Clinical picture: the disease develops gradually, within 2-3 days. Intoxication is poorly expressed, catarrhal phenomena come to the fore. The temperature rarely rises above 38 °C. In the pharynx, a slight reddening of the mucous membrane is determined, the back wall of the pharynx is “granular”. A hallmark of parainfluenza is the defeat of the larynx (laryngitis). It is manifested by a strong, dry, "barking" cough.

Features in children: in children under 6 months. parainfluenza is rare. Catarrhal phenomena predominate, croup syndrome occurs rarely. Complications: in children 1-5 years old, stenosing laryngitis ("false croup") most often develops. This emergency requires immediate hospitalization of the child. In adults, the syndrome practically does not occur.

Treatment is symptomatic: antitussives (Codelac, Tusuprex, Terpinkod) and expectorants (Mukaltin, ACC, Ambrobene). For bacterial infections, antibiotics are used in accordance with the sensitivity of the pathogen. Prevention: not developed.

adenovirus infection

Adenovirus conjunctivitis

Causative agent: adenovirus. 49 strains are dangerous for humans, of which strains 1, 3, 4, 5, 7, 8, 12, 14 and 21 are of key importance. The source of the pathogen is sick people and virus carriers. They secrete the virus with discharge of the upper respiratory tract and conjunctiva of the eyes up to 5-7, sometimes 25 days of illness, with feces - up to 3 weeks. Key route of spread: airborne; food and water transmission routes are possible. The highest incidence is noted in the autumn-winter months. Incubation period: 5 to 14 days, 7 days on average.

Clinical picture: the peak period begins acutely, but the symptoms of the disease develop sequentially. This infection is characterized by a prolonged temperature (up to 2 weeks), pronounced local catarrhal phenomena. The appearance of the patient is typical: his face is puffy, there is abundant mucous discharge from the nose, conjunctivitis. In addition, the phenomena of acute tonsillitis are expressed with a simultaneous increase in the size of the cervical and submandibular lymph nodes. The defeat of the intestinal lymph nodes (mesadenitis) may be accompanied by pain in the abdomen, resembling the clinic of acute appendicitis. Rarely, a maculopapular rash occurs.

Features in children: higher than in adults, temperature (up to 39 ° C), pronounced symptoms of intoxication and dehydration with diarrhea.

Complications: pneumonia, sinusitis, bacterial infections.

Treatment: only symptomatic. The treatment regimen is similar for all SARS.

Prevention: immunization with an oral live vaccine (USA) according to epidemiological indications.

Chicken pox

Rash with chickenpox

Causative agent: herpes virus type 3 varicelta-zoster (VZV). In the environment, it is unstable, sensitive to disinfecting solutions, UV radiation. The source of the pathogen is sick people. Key route of transmission: airborne. Patients with chickenpox are contagious to others a day before the rash appears and up to 5 days after the last elements of the rash appear. The virus has a high volatility, infection occurs at a distance of up to 20 m. A vertical mechanism of transmission from mother to fetus has also been described. Incubation period: 10 to 21 days, 14 days on average.

Clinical picture: in adults, body temperature, symptoms of intoxication are more pronounced than in children. The elements of the rash do not appear all at once. Each napping is accompanied by an episode of fever. At first, they look like small red spots, which form into a tubercle within a few hours, and then into a bubble filled with transparent contents. After 1-2 days, they dry out, become covered with a brown crust, after which the pigmented spots remain on the skin, in some cases - scars. Rash elements are located on all parts of the skin, especially on the scalp (a hallmark of chickenpox).

The disease is characterized by a variety of rashes. On one area of ​​the skin, you can find elements that are at different stages of development (from a spot to a crust), as well as of different sizes (from 1 - 2 to 5 - 8 mm). The rash is often associated with intense itching. In adults, it is more abundant, the period of rashes is longer, pustules appear more often. Often accompanied by multiple enlargement of lymph nodes.

Features in children: the disease usually begins with a rash. At the same time, body temperature rises from 37.5 to 38.5 - 39 ° C. The severity of fever and intoxication depends on the number of rashes. Its duration, as a rule, does not exceed 3-5 days. Complications: pneumonia, meningitis, keratitis, bacterial infections.

Treatment: in an uncomplicated form, treatment is symptomatic. The elements of the rash are treated with antiseptics (brilliant green, chlorophyllipt, etc.). At high temperatures, anti-inflammatory drugs are prescribed. In children, the use of acetylsalicylic acid is contraindicated! In severe forms, treatment is carried out in a hospital with the use of antiviral drugs (acyclovir) and immunoglobulins. In cases of bacterial infections, broad-spectrum antibiotics are used.

Prevention: isolation of the patient for 9 days from the moment of illness. Specific prophylaxis includes the administration of a vaccine.

Measles

Rash with measles

Filatov spots

Causative agent: measles virus. The causative agent is unstable in the environment, at a temperature of 60 ° C it is destroyed within a few seconds, and instantly dies under the influence of sunlight and UV radiation. It remains at room temperature for 3-4 hours. The source of the pathogen is a sick person who becomes contagious to others in the last 2 days of the incubation period, during the entire catarrhal period and the appearance of rashes. From the 5th day of the appearance of the rash, the patient becomes non-infectious. The key route of spread of the pathogen: airborne. Incubation period: 8 - 10 days, but can be extended up to 17 days.

Clinical picture: there are three main periods: catarrhal (or initial, prodromal), rashes and pigmentation. Initial lasts from 3 - 4 to 5 - 7 days. Clinical symptoms are fever up to 38.5 - 39.0 °C, conjunctivitis, rhinitis, tonsillitis, pharyngitis. Catarrhal phenomena are steadily progressing. Patients have abundant discharge from the nose, initially mucous, then with elements of pus, as well as a hoarse or hoarse voice, dry obsessive cough. Observed swelling of the eyelids, photophobia, redness of the conjunctiva, followed by the development of purulent conjunctivitis. The general condition of patients is significantly disturbed: there is a decrease in appetite, sleep disturbance. Symptoms of general intoxication are pronounced, convulsions, impaired consciousness may occur.

The catarrhal period of measles is characterized by the appearance of pinkish-red small spots on the soft and hard palate. They are usually found 1 - 2 days before the rash on the skin. In a number of patients during this period, a mild, mild, punctate rash appears on the skin. A distinctive symptom of measles in the initial period are Filatov's spots, which appear 1 to 2 days before skin rashes. They are found on the mucous membrane of the cheeks (near the molars), lips and gums. These are grayish-white papules the size of poppy seeds, resembling large salt crystals or semolina, surrounded by a whisk.

The period of rash begins on the 4th - 5th day of illness and is characterized by the appearance of a pink spotted rash against the background of normal skin color. Its main feature is its staging. Usually on the 1st day, the elements of the rash appear on the face, on the 2nd - on the trunk and the parts of the arms closest to it, on the 3rd - the rash spreads to the limbs completely. The first elements appear behind the auricles, on the back of the nose in the form of small spots or papules of a rich pink color. Within a few hours, they increase in size. The elements merge, and the rash becomes typical for measles - maculopapular. As a rule, it is very plentiful. But it can also be scarce in the form of individual elements. They quickly darken and then disappear (pigmentation period).

Features in children: on the 1st day of the rash in children, the temperature is higher compared to the catarrhal period. Sometimes 1 - 2 days before the start of this period, the body temperature drops, but when the rash appears, it rises again. Subsequently, the fever persists throughout the entire period of the rash. Complications: pneumonia, otitis media, meningitis, encephalitis, bacterial infections.

Treatment: the room in which the patient is located should be shaded. Plentiful drinking is shown. Assign inhalations, antitussives. There is evidence of the effectiveness of interferon preparations: interferon alfa is used. Antibiotics are prescribed in case of bacterial mixed infections. For debilitated patients, children under 1 year of age, according to individual indications, it is advisable to use preventive use of broad-spectrum antibiotics.

Prevention: isolation of the patient until the 4th day from the onset of rashes. For contacts - quarantine for 17 days. The unvaccinated are immunized. Scheduled immunization with live measles vaccine from 12 months, revaccination at 6 years.

Rubella

Rubella rash

Causative agent: rubella virus. The pathogen is unstable in the environment. Instantly dies when boiled, at room temperature it lives for several hours. The source of the pathogen is a sick person. The only transmission mechanism is aerosol, the way is airborne. The causative agent is excreted from the patient's body with discharge of the mucous membrane of the upper respiratory tract, most intensively one day before the onset of the disease. Most often, children aged 3 to 6 years are sick. Incubation period: 10 to 24 days, 14 days on average.

Clinical picture: the disease begins with mild catarrhal phenomena resembling SARS: dry cough, sore throat, nasal congestion. On the soft palate, rashes in the form of red spots may appear. Mild conjunctivitis is noted. A typical manifestation of the disease is a multiple enlargement of the lymph nodes, which may precede catarrhal phenomena. This is especially true for the occipital and posterior cervical lymph nodes. Sometimes there is an increase in the size of the spleen. Body temperature rises in the range from 37.5 to 39 °C. The fever lasts from 2 to 4 days and is accompanied by mild intoxication.

The rash appears on the 1st - 3rd day of illness. Its first elements are watching the ears, on the face. Within 12-36 hours, the rash spreads to the trunk and extremities, where it is more abundant than on the face. The brightest on the back, buttocks, extensor surfaces of the limbs. The elements of the rash are rounded pink spots, 2–5 mm in diameter, not rising above the skin surface. Sometimes they merge with each other. The rash may be accompanied by mild itching. It disappears in 2 - 4 days, leaving no pigmentation.

Features in children: in children, the disease occurs with a shorter period of fever, the frequency of complications is much lower.

Complications: the most common is polyarthritis, especially in adults. It develops 4 to 7 days after the rash appears. The metacarpophalangeal and interphalangeal joints suffer predominantly, less often the knee and elbow joints. Another formidable complication is encephalitis.

Treatment: bed rest is prescribed for the period of fever. The diet is gentle, the drink is warm, plentiful. The vast majority of patients do not need other treatment. For fever and arthritis, symptomatic agents (Ibuprofen) are sometimes prescribed.

Prevention: isolation of the patient until the 4th day from the onset of rashes. Scheduled (calendar) immunization with live measles vaccine from 12 months, revaccination at 6 years. Immunization is recommended for unvaccinated pubertal girls.

Rotavirus infection

Pathogen: representatives of the rotavirus family. They are stable in the environment, on various objects they remain from 10 to 30 days, in feces up to 7 months. The source of the pathogen is sick people. On the first day of the disease, the patient's stool contains many virions. After the 5th day of illness, the amount of virus in the blood and feces falls rapidly. In most cases, the duration of its allocation does not exceed 1 month. Virus carrying without clinical manifestations lasts for several months. The route of spread of the virus is fecal-oral. The key transmission factor is water. Incubation period: from 15 hours to 5 days.

Clinical picture: the onset of the disease is acute. The development of the clinical picture almost always begins with vomiting, which occurs after eating or drinking. The vomit is copious, watery. After a few hours, diarrhea joins with a frequency of up to 10 times a day. Then, signs of intoxication are added to the symptoms of damage to the organs of the gastrointestinal tract: headache, weakness, a feeling of "ache" in the muscles and joints. The fever is unexpressed and is of short duration. Some patients develop catarrhal syndrome: runny nose, cough.

Features in children: the disease occurs with lactase deficiency syndrome. This is expressed in the form of bloating, frequent frothy stools with an admixture of whitish "flakes". Rotavirus infection in children often leads to dehydration, which is why the disease is dangerous.

Treatment is carried out in a hospital. Specific therapy is carried out with anti-rotavirus immunoglobulin. Interferon preparations (interferon-alpha) are actively used. To replenish fluid losses, infusion therapy is carried out. At I-II degree of dehydration, solutions for oral use are given (Oralit, Citroglucosolan, etc.), at III-IV degree, intravenous infusions of solutions are carried out. For children, the appointment of sorbents (activated carbon, Smecta) is mandatory. The diet is lactose-free, children on breast and artificial feeding are transferred to special lactose-free mixtures. Prevention has not been developed. Isolation of the patient and hygiene measures have little effect.

Coxsackievirus and ECHO virus infection

Pathogen: Coxsackieviruses (A and B) and ECHO (enteroviruses). The only source of the infectious agent is a person (sick or virus carrier), who actively releases them into the external environment with feces. In addition, the virus is intensively excreted from the mucus of the upper respiratory tract. This occurs most actively on the first day of illness, but can last for several months. The main mechanism of transmission of the pathogen is fecal-oral, the main ways are water, food (most often through vegetables). Incubation period: 2 to 10 days.

Clinical picture: the symptoms are varied. There is no single classification of the forms of the disease. In most cases, the same symptoms are noted. The disease, as a rule, begins acutely with an increase in body temperature up to 38 - 39 ° C, headache, a feeling of "ache" in the muscles. On general examination, reddening of the face and neck, mucous membranes, tonsils, soft palate, palatine arches and posterior pharyngeal wall is noted, often inflammation of the cervical lymph nodes.

The most characteristic manifestation of enterovirus infection is serous meningitis. The disease begins acutely with fever, intoxication, sometimes catarrhal phenomena and digestive disorders develop.

Features in children: babies can develop a severe (systemic) form of enterovirus infection - encephalomyocarditis, often fatal. Complications: encephalitis, myocarditis, pneumonia, bacterial infections.

Treatment: carried out in a hospital. Apply anti-inflammatory drugs (ibuprofen, etc.), with meningitis with cerebral edema - diuretics (mannitol, furosemide, diacarb, etc.). In severe cases, systemic administration of glucocorticoids (dexamethasone) is used.

Prevention: isolation of patients for 2 weeks. Specific prophylaxis has not been developed.

Viral diseases of the respiratory system and organs of the gastrointestinal tract occupy the first places in terms of prevalence in adults and children. Knowledge of the clinical symptoms of major diseases, methods of treatment and prevention is necessary for everyone. This will allow timely assistance to the sick and prevent infection of others. In any case, a doctor's consultation is necessary!

Viruses are non-cellular infectious agents that have a genome (DNA and RNA), but are not gifted with a synthesizing apparatus. To reproduce, these microorganisms need cells of more highly organized organisms. Once in the cells, they begin to multiply, causing the development of various diseases. Each virus has a specific mechanism of action on its host. Sometimes a person does not even suspect that they are a virus carrier, since the virus does not harm health, this condition is known as latency, such as herpes.

To prevent viral diseases, it is important to maintain a healthy lifestyle, strengthening the body's defenses.

Origin and structure

There are several hypotheses for the origin of viruses. Science offers a version of the origin of viruses from fragments of RNA and DNA that were released from a large organism.

Coevolution suggests that viruses appeared simultaneously with living cells as a result of the construction of complex sets of nucleic acids and proteins.

Questions about how it reproduces and is transmitted are studied by a special section of microbiology - virology.

Each viral particle has genetic information (RNA or DNA) and a protein membrane (capsid) that acts as a defense.

Viruses come in a variety of shapes, ranging from simple helical to icosahedral. The standard value is approximately 1/100 of the size of an average bacterium. However, most viruses are very small, making them difficult to examine under a microscope.

Is living matter a virus?

There are two definitions of life forms of viruses. According to the first, extracellular agents are a collection of organic molecules. The second definition states that viruses are a special form of life. It is impossible to answer the question of what viruses exist, specifically and definitively, since biology assumes the constant emergence of new species. They are similar to living cells in that they have a special set of genes and evolve according to the way the natural set. They require a host cell to exist. The lack of their own metabolism makes it impossible to reproduce without outside help.

Modern science has developed a version according to which certain bacteriophages have their own immunity, capable of adapting. This is proof that viruses are a form of life.

Viral diseases - what is it?

Viruses of the plant world

If you ask yourself what viruses are, then, in addition to the human body, you can distinguish a special type of viruses that infect plants. They are not dangerous to humans or animals, since they can only reproduce in plant cells.

Artificial viruses

Artificial viruses are created to produce vaccines against infections. The list of artificially created viruses in the arsenal of medicine is not fully known. However, it is safe to say that the creation of an artificial virus can have a lot of consequences.

Such a virus is obtained by introducing into the cell an artificial gene that carries the information necessary for the formation of new types.

Viruses that infect the human body

What viruses are on the list of extracellular agents dangerous to humans and causing irreversible changes? Here is an aspect of the study of modern science.

The simplest viral disease is the common cold. But against the background of a weakened immune system, viruses can cause quite serious pathologies. Each pathogenic microorganism affects the organism of its host in a certain way. Some viruses can live in the human body for years and do no harm (latentness).

Certain latent species are even beneficial to humans, as their presence generates an immune response against bacterial pathogens. Some infections are chronic or lifelong, which is purely individual and due to the protective ability of the virus carrier.

Spread of viruses

Transmission of viral infections in humans is possible from person to person or from mother to baby. The rate of transmission or epidemiological status depends on the population density of the area, the weather and season, and the quality of medicine. It is possible to prevent the spread of viral pathologies if it is timely clarified which virus is currently detected in most patients, and appropriate preventive measures are taken.

Kinds

Viral diseases manifest themselves in completely different ways, which is associated with the type of extracellular agent that caused the disease, with the place of localization, with the rate of development of the pathology. Human viruses are classified as lethal and indolent. The latter are dangerous because the symptoms are unexpressed or weak, and it is not possible to quickly detect the problem. During this time, the pathogenic organism can multiply and cause serious complications.

Below is a list of the main types of human viruses. It allows you to clarify which viruses are there and which pathogenic microorganisms cause diseases that are dangerous to health:

1. Orthomyxoviruses. This includes all types of influenza viruses. To find out which influenza virus caused the pathological condition, special tests will help.
2. adenoviruses and rhinoviruses. They affect the respiratory system, cause SARS. Symptoms of the disease are similar to flu, can cause such serious complications as pneumonia, bronchitis.
3. Herpesviruses. Activated against the background of reduced immunity.
4. Meningitis. Pathology is caused by meningococci. The mucous membrane of the brain is affected, the nutrient substrate for the pathogenic organism is the cerebrospinal fluid.
5. Encephalitis. It has a negative effect on the membrane of the brain, causing irreversible changes in the central nervous system.
6. Parvovirus. The diseases caused by this virus are very dangerous. The patient has convulsions, inflammation of the spinal cord, paralysis.
7. Picornaviruses. Cause hepatitis.
8. Orthomyxoviruses. Provoke mumps, measles, parainfluenza.
9. Rotavirus. The extracellular agent causes enteritis, intestinal flu, gastroenteritis.
10. rhabdoviruses. They are causative agents of rabies.
11. Papoviruses. Cause papillomatosis in humans.

Retroviruses. They are the causative agents of HIV, and after AIDS.

life-threatening viruses

Some viral diseases are quite rare, but they pose a serious danger to human life:

1. Tularemia. The disease is caused by the Francisellatularensis bacillus. The clinical picture of the pathology resembles the plague. It enters the body by airborne droplets or by a mosquito bite. Transmitted from person to person.
2. Cholera. The disease is fixed very rarely. Vibrio cholerae virus enters the body through the use of contaminated water, contaminated food.
3. Creutzfeldt-Jakob disease. In most cases, the patient has a lethal outcome. It is transmitted through contaminated animal meat. The causative agent is a prion - a special protein that destroys cells. Manifested by a mental disorder, severe irritation, dementia.

It is possible to determine which type of virus caused the disease by conducting laboratory tests. An important argument is the epidemic state of the region. It is also important to find out which virus is currently circulating.

Signs of viral infections and possible complications

The main part of the viruses provokes the occurrence of acute respiratory diseases. The following manifestations of SARS are distinguished:

• development of rhinitis, cough with clear mucus;
• an increase in temperature to 37.5 degrees or fever;
• feeling of weakness, headaches, decreased appetite, muscle pain.

Late treatment can cause serious complications:

• adenovirus can cause inflammation of the pancreas, which leads to the development of diabetes;
• beta-hemolytic streptococcus, which is the causative agent of tonsillitis and other types of inflammatory diseases, with reduced immunity can provoke diseases of the heart, joints, epidermis;
• influenza and SARS are often complicated by pneumonia in children, elderly patients, pregnant women.

Viral pathologies can also cause other serious complications - sinusitis, joint damage, heart pathology, chronic fatigue syndrome.

Diagnostics

Experts determine a viral infection by common symptoms, based on which virus is currently circulating. Virological studies are used to determine the type of virus. Modern medicine widely uses methods of immunodiagnostics, including immunoindication, serodiagnostics. Which ones to pass the specialist decides on the basis of a visual examination and the collected anamnesis.

Appoint:

• enzyme immunoassay;
• radioisotope immunoassay;
• study of hemagglutination inhibition response;
• immunofluorescence reaction.

Treatment of viral diseases

The course of treatment is chosen depending on the pathogen, specifying which types of viruses caused the pathology.

For the treatment of viral diseases are used:

1. Drugs that stimulate the immune system.
2. Medicines that destroy a specific type of virus. The diagnosis of a viral infection is necessary, since it is important to clarify which virus responds best to the selected drug, which makes it possible to make therapeutic therapy more targeted.
3. Medicines that increase the sensitivity of cells to interferon.

For the treatment of common viral diseases, apply:

1. "Acyclovir". Assign for herpes, it eliminates the pathology completely.
2. Relezan, Ingavirin, Tamiflu. Assign for different types of influenza.
3. Interferons together with Ribavirin are used to treat hepatitis B. A new generation drug, Simeprevir, is used to treat hepatitis C.

Prevention

Preventive measures are selected depending on the type of virus.

Preventive measures are divided into two main areas:

1. Specific. They are carried out with the aim of developing specific immunity in humans through vaccination.
2. Nonspecific. Actions should be aimed at strengthening the body's defense system, by providing small physical exertion, a properly composed diet and personal hygiene.

Viruses are living organisms that are almost impossible to avoid. To prevent serious viral pathologies, it is necessary to vaccinate according to the schedule, lead a healthy lifestyle, and organize a balanced diet.