Who belongs to viruses. What viruses are: types, classification, characteristics, viral diseases, treatment and consequences. Viral content in examples

Viruses (biology deciphers the meaning of this term as follows) are extracellular agents that can only be reproduced with the help of living cells. Moreover, they are capable of infecting not only people, plants and animals, but also bacteria. Bacterial viruses are usually called bacteriophages. Not so long ago, species were discovered that infect each other. They are called "satellite viruses".

General characteristics

Viruses are a very numerous biological form, as they exist in every ecosystem on planet Earth. They are studied by such a science as virology - a section of microbiology.

Each viral particle has several components:

Genetic data (RNA or DNA);

Capsid (protein shell) - has a protective function;

Viruses have a fairly diverse form, ranging from the simplest spiral to icosahedral. Standard sizes are about one-hundredth the size of a small bacterium. However, most of the specimens are so small that they cannot even be seen under a light microscope.

They spread in several ways: viruses that live in plants are moved by insects that feed on herbal juices; animal viruses are carried by blood-sucking insects. U are transmitted in a large number of ways: by airborne droplets or sexually, as well as through blood transfusion.

Origin

In our time, there are three hypotheses for the origin of viruses.

Briefly about viruses (on the biology of these organisms, our knowledge base, unfortunately, is far from perfect) you can read in this article. Each of the theories listed above has its drawbacks and unproven hypotheses.

Viruses as a form of life

There are two definitions of the life form of viruses. According to the first, extracellular agents are a complex of organic molecules. The second definition tells us that viruses are a special form of life.

Viruses (biology implies the emergence of many new types of viruses) are characterized as organisms on the border of the living. They are similar to living cells in that they have their own unique set of genes and evolve based on the method of natural selection. They can also multiply, creating their own copies. Since viruses are not scientists, they do not consider them as living matter.

In order to synthesize their own molecules, extracellular agents need a host cell. The lack of their own metabolism does not allow them to reproduce without assistance.

Virus classification by Baltimore

What viruses are, biology describes in sufficient detail. David Baltimore (Nobel laureate) developed his own classification of viruses, which is still successful today. This classification is based on the way mRNA is formed.

Viruses must form mRNA from their own genomes. This process is necessary for the replication of its own nucleic acid and the formation of proteins.

The classification of viruses (biology takes into account their origin), according to Baltimore, is as follows:

Double-stranded DNA viruses without RNA stage. These include mimiviruses and herpeviruses.

Single-stranded DNA with positive polarity (parvoviruses).

Double-headed RNA (rotaviruses).

Single-stranded RNA of positive polarity. Representatives: flaviviruses, picornaviruses.

Single-stranded RNA molecule of double or negative polarity. Examples: filoviruses, orthomyxoviruses.

Single-stranded positive RNA, as well as the presence of DNA synthesis on the RNA template (HIV).

Double-stranded DNA, and the presence of DNA synthesis on an RNA template (hepatitis B).

Life Span

Examples of viruses in biology are found almost at every step. But for all, the life cycle proceeds almost the same. Without a cellular structure, they cannot reproduce by the method of division. Therefore, they use materials that are inside the cell of their host. Thus, they reproduce a large number of copies of themselves.

The cycle of a virus consists of several stages, which are overlapping.

At the first stage, the virus attaches itself, that is, forms a specific bond between its proteins and the receptors of the host cell. Next, you need to penetrate the cell itself and transfer your genetic material to it. Some species also carry proteins. The capsid is then lost and the genomic nucleic acid is released.

Human diseases

Each virus has a specific mechanism of action on its host. This process involves the lysis of cells, which leads to their death. When a large number of cells die off, the entire body begins to function poorly. In many cases, viruses may not harm human health. In medicine, this is called latency. An example of such a virus is herpes. Some latent species can be beneficial. Sometimes their presence triggers an immune response against bacterial pathogens.

Some infections can be chronic or lifelong. That is, the virus develops despite the protective functions of the body.

Epidemics

Horizontal transmission is the most common type of virus spreading among humanity.

The rate of transmission of the virus depends on several factors: population density, the number of people with poor immunity, as well as the quality of medicine and weather conditions.

Body protection

The types of viruses in biology that can affect human health are innumerable. The very first defense reaction is innate immunity. It is made up of special mechanisms that provide non-specific protection. This type of immunity is not able to provide reliable and long-term protection.

When vertebrates develop acquired immunity, special antibodies are produced that attach to the virus and make it safe.

However, acquired immunity is far from being formed against all existing viruses. For example, HIV constantly changes its amino acid sequence, so it leaves the immune system.

Treatment and prevention

Viruses in biology are a very common phenomenon, so scientists have developed special vaccines containing "killer substances" for the viruses themselves. The most common and effective method of struggle is vaccination, which creates immunity to infections, as well as antiviral drugs that are able to selectively inhibit the replication of viruses.

Biology describes viruses and bacteria mainly as harmful inhabitants of the human body. Currently, with the help of vaccination, it is possible to overcome more than thirty viruses that have settled in the human body, and even more in the body of animals.

Preventive measures against viral diseases should be carried out on time and with high quality. For this, humanity must lead a healthy lifestyle and try in every possible way to increase immunity. The state, on the other hand, must arrange quarantines on time and provide good medical care.

Plant viruses

Artificial viruses

The ability to create viruses in an artificial environment can have many consequences. The virus cannot die out completely as long as there are bodies that are sensitive to it.

Viruses are weapons

Viruses and the biosphere

At the moment, extracellular agents can boast the largest number of individuals and species living on planet Earth. They perform an important function by regulating the size of populations of living organisms. Very often they form symbiosis with animals. For example, the venom of some wasps contains components of viral origin. However, their main role in the existence of the biosphere is life in the sea and ocean.

One teaspoon of sea salt contains approximately a million viruses. Their main purpose is to regulate life in aquatic ecosystems. Most of them are absolutely harmless to flora and fauna.

But these are not all positive qualities. Viruses regulate the process of photosynthesis, therefore they increase the percentage of oxygen in the atmosphere.

There is an opinion that animals, plants and humans prevail in numbers on the planet Earth. But this is actually not 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 for humans.

Hantaviruses are a genus of viruses transmitted to humans through contact with rodents or their waste products. Hantaviruses cause various diseases belonging to such groups of diseases as “hemorrhagic fever with renal syndrome” (mortality rate on average 12%) and “hantavirus cardiopulmonary syndrome” (mortality rate up to 36%). The first major outbreak of the disease 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 impact of a then unknown virus that caused internal bleeding and impaired kidney function. Interestingly, this particular virus is considered the likely cause of the epidemic in the 16th century, which exterminated the Aztec people.

Influenza virus is a virus that causes acute respiratory infections in humans. Currently, there are more than 2 thousand of its variants, classified according to three serotypes A, B, C. A 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 in the world from 250 to 500 thousand people die from seasonal flu epidemics (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. Early symptoms include fever, headache, and muscle pain. In the later, jaundice, pancreatitis, weight loss, delirium and neuropsychiatric symptoms, bleeding, hypovolemic shock, and multiple organ failure, most commonly the liver. Marburg fever is one of the ten deadly 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. It is transmitted by the fecal-oral route. The disease is usually easy to treat, but more than 450,000 children under the age of five die each year worldwide, most of whom live in underdeveloped countries.

The Ebola virus is a genus of viruses that causes Ebola haemorrhagic 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 by direct contact with 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 renal and liver function, and in some cases, internal and external bleeding. According to the US Centers for Disease Control, as of 2015, 30,939 people were infected with Ebola, of whom 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 is found 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 the 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, vomiting. On the second day, a rash appears, which eventually turns into purulent blisters. In the 20th century, this virus has claimed the lives of 300-500 million people. Around US $ 298 million was spent on the Smallpox Campaign from 1967 to 1979 (the equivalent of 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 damage to the central nervous system occurs. This disease is transmitted through saliva when bitten by an infected animal. It is accompanied by an increase in temperature to 37.2–37.3, poor sleep, patients become aggressive, violent, hallucinations, delirium, a feeling of 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 have been recorded without the use of vaccination, 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 system, 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 5,000 lead to the death of the patient. The natural reservoir of Lassa fever is the multi-nipple rat.

Human Immunodeficiency Virus (HIV) is the most dangerous human virus, the causative agent of HIV / AIDS, which is transmitted through direct contact of mucous membranes or blood with bodily fluid of the patient. In the course of HIV infection, all new strains (varieties) of the virus are formed in the same person, 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 the data for 2011, 60 million people in the world fell ill with HIV infection, of which 25 million died, and 35 million continue to live with the virus.

Methods of dealing with viral diseases.

Diagnostics of viral diseases.

Methods of transmission of viral diseases.

1. When plant propagation inoculation, on the stock. It is important that the queen cells are free of viruses.

2. Contact contamination... As a result of leaf contacts, for example, through breakage of hairs (trichomes) during friction of leaves, through processing tools, garden tools, workers' clothes, especially when pinching, cutting flowers. (tulip variegation virus).

3. Vector transmission... The most common way. Viruses can be transmitted by insects, nematodes, fungi. Most of all carriers of gray aphids, leafhoppers, thrips, whiteflies. (potato virus, mosaic virus of cucumber, pea, beet)

Symptoms of viral diseases can vary greatly depending on a wide variety of conditions, so diagnosing viral diseases can be difficult.

1. Visual inspection. Fastest but least accurate method.

2. Serological method. If a virus is introduced into the blood of an animal, then specific proteins are formed in the blood serum - antibodies to this virus, which translate it into a harmless state. To diagnose the disease, a drop of the juice of the affected plant is mixed with a drop of diagnostic serum from the blood of an animal previously treated with a known virus. If there is this virus in the juice, then as a result of the reaction of the virus and antibodies in the mixture, a flocculent precipitate is formed, by the intensity of the precipitation of which one can judge the relative amount of the virus in the plant juice.

3. Indication method. Based on the infection of the indicator plant with the juice of the test plant. Indicators respond with definite clear symptoms to infection with a given virus. This is more sensitive, but also more time consuming.

4. Inclusion analysis method... With a razor blade, a section of the epidermis with leafy hairs is cut off and under a microscope they look for viral inclusions in the hair cells.

1. Destruction of diseased plants.

2. Use only healthy planting material.

3. Fight against insects - carriers of viruses.

4. Improvement of plants by the meristem culture method.

5. Disinfection of planting material by thermotherapy.

On garden carnation about 9 viral diseases were noted:

Bushiness virus. A sharp shortening of internodes is noted, dormant buds start to grow, forming many lateral shoots, the plants do not bloom.

Soft mosaic virus. There are slight mottling on the leaves, light streaks on the flowers.

Ring spot virus. Chlorotic concentric rings on the leaves

Clove banded virus. Whitish, yellow, brown stripes or streaks on the leaves.

Many species of aphids and nematodes carry these viruses.

Yellow dwarf virus Luke. Allium virus 1. There are short yellow stripes at the base of the leaves and on the flower arrows. The leaves turn yellow, the arrows are curved. The flower heads become smaller, the bulbs are small, the plants have a dwarf appearance.

On apple trees several types of viruses have been noted:

Apple Mosaic Virus. On the leaves there is a light mosaic in the form of small irregular cream or yellow spots. In summer, in place of spots - necrosis. Deformation of the leaf blade is sometimes observed.

Rosette virus. Rosettes of very small, ugly leaves are formed on the shoots.

Drooping Virus. The plant has a "weeping" appearance. The shoots droop, the wood in them is soft due to the absence of lignification processes. The turgor in the cells is reduced, there is a lag in growth.

Paniculate or bushiness virus. The overdevelopment of numerous shoots occurs on individual branches.

Fruit cracking virus. The flowering is belated, there are few flowers, the fruits are single, the affected shoots die off. On the fruit - stellate cracks around the calyx.

Asters ringed spot virus. It causes the formation of chlorotic rings and zigzag lines on the leaves of asters - Chinese callistephus, zinnia, perennial aster.

Viral diseases affect cells in which there are already violations, which is used by the pathogen. Modern research has proven that this happens only with a strong weakening of the immune system, which is no longer able to fight the threat at the proper level.

Features of viral infections

Types of viral diseases

It is customary to distinguish these pathogens according to their genetic characteristics:

• DNA - human colds viral diseases, hepatitis B, herpes, papillomatosis, chickenpox, lichen;
• RNA - influenza, hepatitis C, HIV, poliomyelitis, AIDS.

Viral diseases can also be classified according to the mechanism of their influence on the cell:

• cytopathic - the accumulated particles break and kill it;
• immune-mediated - the virus embedded in the genome is asleep, and its antigens come to the surface, putting the cell under attack by the immune system, which considers it an aggressor;
• peaceful - the antigen is not produced, the latent state persists for a long time, replication starts when favorable conditions are created;
• degeneration - the cell mutates into a tumor.

How is the virus spread?

A viral infection spreads:

1. Airborne droplets. Respiratory viral infections are spread by drawing in mucus particles that are sprayed on when sneezing.
2. Parenteral In this case, the disease gets from mother to child, during medical manipulations, sex.
3. Through food. Viral diseases are transmitted through water or food. Sometimes they are dormant for a long time, manifesting themselves only under external influence.

Why do viral diseases have the character of epidemics?

Many viruses spread quickly and massively, which provokes the outbreak of epidemics. The reasons for this are as follows:

1. Ease of distribution. Many serious viruses and viral diseases are easily transmitted by inhaled droplets of saliva. In this form, the pathogen can maintain activity for a long time, therefore it is able to find several new carriers.
2. Reproduction rate. After entering the body, the cells are affected one after another, providing the necessary nutrient medium.
3. Difficulty of elimination. It is not always known how to treat a viral infection, this is due to the lack of knowledge, the possibility of mutations and the difficulties of diagnosis - at the initial stage it is easy to confuse it with other problems.

Symptoms of a viral infection

The course of viral diseases may differ depending on their type, but there are common points.

1. Fever. It is accompanied by a rise in temperature up to 38 degrees, without it only mild forms of ARVI pass. If the temperature is higher, then this indicates a severe course. It lasts no longer than 2 weeks.
2. Rash. Viral skin diseases are accompanied by these manifestations. They can look like spots, roseola, and vesicles. Typical for childhood, in adults, rashes are less common.
3. Meningitis. It occurs with enterovirus and, more often, children encounter.
4. Intoxication- loss of appetite, nausea, headache, weakness and lethargy. These signs of a viral disease are caused by toxins released by the pathogen during activity. The strength of the impact depends on the severity of the disease, it is more difficult for children, adults may not even notice it.
5. Diarrhea. Typical for rotaviruses, the stool is watery, does not contain blood.

Human viral diseases - list

It is impossible to name the exact number of viruses - they are constantly changing, adding to the extensive list. Viral diseases, the list of which is presented below, are the most famous.

1. Flu and colds. Their signs are: weakness, fever, sore throat. Antiviral drugs are used, when bacteria attach, antibiotics are additionally prescribed.
2. Rubella. The eyes, respiratory tract, cervical lymph nodes and skin are affected. It spreads by airborne droplets, accompanied by high fever and skin rashes.
3. Piggy. The respiratory tract is affected; in rare cases, the testes are affected in men.
4. Yellow fever. Harmful to the liver and blood vessels.
5. Measles. Dangerous for children, affects the intestines, respiratory tract and skin.
6. . Often arises against the background of other problems.
7. Polio. Penetrates into the bloodstream through the intestines and respiration, with damage to the brain, paralysis occurs.
8. Angina. There are several types, characterized by headache, high fever, severe sore throat and chills.
9. Hepatitis. Any variety causes yellow skin, darkening of urine and colorless feces, which indicates a violation of several body functions.
10. Typhus. Rare in the modern world, affects the circulatory system, can lead to thrombosis.
11. Syphilis. After the defeat of the genitals, the pathogen enters the joints and eyes, spreads further. Has no symptoms for a long time, therefore periodic examinations are important.
12. Encephalitis. The brain is affected, a cure cannot be guaranteed, the risk of death is high.

The most dangerous viruses in the world for humans

The list of viruses that pose the greatest danger to our body:

1. Hantavirus. The pathogen is transmitted from rodents, causes various fevers, the mortality rate in which ranges from 12 to 36%.
2. Flu. These include the most dangerous viruses known from the news, different strains can cause a pandemic, a severe course more affects the elderly and young children.
3. Marburg. Discovered in the second half of the 20th century, it is the cause of hemorrhagic fever. Transmitted from animals and infected people.
4. . It causes diarrhea, the treatment is simple, but in underdeveloped countries 450 thousand children die from it every year.
5. Ebola. As of 2015, the mortality rate is 42%, it is transmitted by contact with the fluids of an infected person. Signs are: a sharp rise in temperature, weakness, sore muscles and throat, rash, diarrhea, vomiting, possible bleeding.
6. . Mortality is estimated at 50%, characterized by intoxication, rash, fever, lymph node involvement. Distributed in Asia, Oceania and Africa.
7. Smallpox. It has been known for a long time, it is dangerous only to people. Rash, high fever, vomiting, and headache are common. The last case of infection occurred in 1977.
8. Rabies. It is transmitted from warm-blooded animals, affects the nervous system. Once signs appear, treatment success is nearly impossible.
9. Lassa. The pathogen is carried by rats, first discovered in 1969 in Nigeria. Kidneys, nervous system are affected, myocarditis and hemorrhagic syndrome begin. Treatment is difficult, fever claims up to 5 thousand lives annually.
10. HIV. It is spread through contact with the fluids of an infected person. Without treatment, there is a chance to live 9-11 years, its difficulty lies in the constant mutation of strains that kill cells.

Fight against viral diseases

The complexity of the fight lies in the constant change of known pathogens that make the usual treatment of viral diseases ineffective. This makes it necessary to search for new drugs, but at the present stage of the development of medicine, most measures are developed quickly, before the epidemic threshold is crossed. The following approaches have been taken:

• etiotropic - preventing the reproduction of the pathogen;
• surgical;
• immunomodulatory.

Antibiotics for viral infection

In the course of the disease, immunity is always suppressed, sometimes it is required to strengthen it to destroy the pathogen. In some cases, with a viral disease, antibiotics are additionally prescribed. This is necessary when a bacterial infection is added, which is killed only in this way. With a pure viral disease, taking these funds will not only worsen the condition.

Prevention of viral diseases

1. Vaccination- effective against a specific pathogen.
2. Strengthening immunity- prevention of viral infections in this way implies hardening, proper nutrition, support with plant extracts.
3. Precautionary measures- exclusion of contacts with sick people, exclusion of unprotected casual sex.

Content

A person is most susceptible to various colds in the autumn and spring. Viral infectious diseases - a type of disease that is caused by an infection that has penetrated into a weakened body. They can wilt in an acute form or sluggish, but treatment must be carried out in both cases, so as not to aggravate the situation, to avoid dangerous complications. A person, on average, suffers from 2 to 3 times a year with colds, but the development of the disease always gets due to viral DNA.

What are viral diseases

Types of viruses

Different types of bacteria, which differ in the place of localization, the rate of development, and signs, can cause the symptoms of pathology. Human viruses have a special classification, conventionally they are divided into fast and slow. The second option is very dangerous in that the symptoms are very weak and it is not possible to immediately detect the problem. This gives her time to multiply, to strengthen. Among the main types of viruses, the following groups are distinguished:

1. Orthomyxoviruses- all influenza viruses.
2. Adenoviruses and Rhinoviruses. They provoke ARVI - an acute respiratory viral infection that affects the respiratory system. Symptoms are very similar to those of the flu and can cause complications (bronchitis, pneumonia)
3. Herpesviruses- Herpes viruses, which can live asymptomatically in the body for a long time, are activated immediately after weakening of the immune system.
4. Meningitis. It is provoked by a meningococcal infection, the mucous membrane of the brain is damaged, the virus feeds on cerebrospinal fluid (cerebrospinal fluid).
5. Encephalitis- affects the lining of the brain, provokes irreversible disturbances in the work of the central nervous system.
6. Parvovirus, which is the causative agent of polio. A very dangerous disease that can cause seizures, spinal cord inflammation, paralysis.
7. Picornaviruses- causative agents of viral hepatitis.
8. Orthomyxoviruses- cause mumps, measles, parainfluenza.
9. Rotavirus- cause enteritis, intestinal flu, gastroenteritis.
10. Rhabdoviruses- pathogens of rabies.
11. Papoviruses- the cause of human papillomatosis.
12. Retroviruses- AIDS pathogens, first HIV develops, and then AIDS.

List of human viral diseases

Medicine knows a huge number of infectious viruses and infections that can provoke various diseases in the human body. Below are only the main groups of diseases that are likely to be encountered:

1. One of the most voluminous groups of viral diseases - flu (A, B, C), different types of colds that cause inflammation in the body, high fever, general weakness and sore throat. Therapy is carried out with the help of fortifying agents, antiviral drugs, if necessary, antibacterial medications are prescribed.
2. Rubella. A common childhood pathology, less common in adults. Symptoms include damage to the membranes of the respiratory tract, skin. eyes, lymph nodes. The virus is transmitted by droplets, always accompanied by high fever, skin rashes.
3. Piggy. A dangerous viral disease affecting the respiratory tract, the salivary glands are severely affected. Rarely seen in adult males, testes are affected by this virus.
4. Measles- often found in children, the disease affects the skin, respiratory tract, intestines. It is transmitted by airborne droplets, the causative agent is paramyxovirus.
5. Poliomyelitis (infantile paralysis). Pathology affects the respiratory tract, intestines, then enters the bloodstream. Further, motor neurons are damaged, which leads to paralysis. The virus is transmitted by droplets, sometimes a child can become infected through stool. In some cases, insects are the vectors.
6. Syphilis. This disease is sexually transmitted, it affects the genitals. Then it affects the eyes, internal organs and joints, heart, liver. Antibacterial agents are used for treatment, but it is very important to determine the presence of pathology immediately, because it may not cause symptoms for a long time.
7. Typhus. It is rare, characterized by a rash on the skin, damage to the blood vessels, which leads to the formation of blood clots.
8. Pharyngitis. The disease is provoked by a virus that enters the human body along with dust. Cold air, streptococci, staphylococci can also provoke the development of pathology. A viral ailment is accompanied by fever, cough, sore throat.
9. Angina- a common viral pathology, which has several subspecies: catarrhal, follicular, lacunar, phlegmonous.
10. Whooping cough... This viral disease is characterized by damage to the upper respiratory tract, laryngeal edema is formed, and severe coughing fits are observed.

The rarest human viral diseases

Most viral pathologies are infectious diseases that are sexually transmitted, airborne. There are a number of diseases that are extremely rare:

1. Tularemia. Pathology in its symptoms strongly resembles the plague. Infection occurs after penetration into the body of Francisella tularensis - this is an infectious bacillus. As a rule, it gets in with the air or when bitten by a mosquito. The disease is transmitted from a sick person.
2. Cholera. This disease is very rare in modern medical practice. Vibrio cholerae virus, which enters the body through dirty water, contaminated food, causes symptoms of pathology. The last outbreak of pathology was recorded in 2010 in Haiti, the disease claimed the lives of more than 4500 people.
3. Creutzfeldt-Jakob disease. A very dangerous pathology that is transmitted through the meat of infected animals. The causative agent is prion - a special protein that begins to actively destroy the cells of the body after penetration. The insidiousness of pathology lies in the absence of symptoms, a person begins to have a personality disorder, severe irritation and dementia appear. It is impossible to cure the disease and the person dies within a year.

Symptoms of the virus

Symptoms do not always appear immediately, some types of viral diseases can proceed for a long time without obvious signs, which becomes a problem with further treatment. Each infectious disease goes through the following stages:

• incubation period;
• premonitory;
• the height of pathology;
• recovery.

The duration of the first stage always depends on the specific type of virus and can last from 2-3 hours to six months. Symptoms will differ depending on the developing disease, but, as a rule, the following manifestations are attributed to the general symptoms of viral pathologies:

• soreness, muscle weakness;
• slight chills;
• persistent body temperature;
• sensitivity of the skin to touch;
• cough, sore throat, watery eyes;
• dysfunction of some organs;
• swollen lymph nodes.

Temperature with a viral infection

This is one of the main reactions of the body to the penetration of any pathogen. Temperature is a defense mechanism that activates all other immune functions to fight off viruses. Most of the diseases occur with a high body temperature. The viral pathologies that provoke this symptom include:

• flu;
• ARVI;
• tick-borne encephalitis;
• childhood diseases: chickenpox, mumps, rubella, measles;
• polio;
• Infectious mononucleosis.

Often there are cases of development of diseases for which the temperature does not rise. The main symptoms are watery compartments with a runny nose, sore throat. The lack of temperature is explained by the insufficient activity of the virus or the immune system is strong, therefore, it does not fully use all possible methods of fighting the infection. If the growth has begun, then high rates are maintained, as a rule, for about 5 days.

Signs

Most viruses provoke the development of acute respiratory pathologies. There is some difficulty in identifying diseases that were caused by bacteria, because the treatment regimen in this case will be very different. There are more than 20 types of viruses that cause SARS, but their main symptoms are similar. The primary signs include the following manifestations:

• rhinitis (runny nose), cough with clear mucus;
• low temperature (up to 37.5 degrees) or fever;
• general weakness, headaches, poor appetite.

How to tell a cold from a virus

There is a difference between the two. A cold occurs during prolonged exposure to the cold, severe hypothermia of the body, which leads to a weakening of immunity and the appearance of an inflammatory process. This is not the name of the disease, but only the reason for the development of other pathologies. Viral pathology often becomes a consequence of a cold, because the body does not have enough defenses to resist the pathogen.

Virus diagnostics

When contacting a doctor, he should conduct a visual examination and take an anamnesis. Usually. viral diseases are accompanied by fever, cough, runny nose, but after 3-4 days a person feels an improvement. Specialists can determine the type of disease based on general symptoms or based on seasonal outbreaks of diseases, for example, flu epidemics often begin in winter, and ARVI in autumn. Determining the exact type of virus will be required for specific treatment (HIV, syphilis, etc.). For this, virological research is used.

This method in medicine is the "gold standard", which is carried out in a special laboratory. As a rule, such methods are used during epidemic outbreaks of viral infectious diseases. Methods of immunodiagnostics (immunoindication, serodiagnostics) have found widespread use for diagnosing pathogens. They are realized through a variety of immune responses:

• enzyme immunoassay (ELISA);
• radioisotope immune analysis (RIA);
• hemagglutination inhibition reaction;
• complement fixation reaction;
• immunofluorescence reaction.

Treatment of viral diseases

The course of therapy is, depending on the type of pathogens. For example, if it is necessary to treat ARVI, childhood viral pathologies (mumps, rubella, measles, etc.), then all medications are used to eliminate symptoms. Subject to bed rest, the diet, the body itself copes with the disease. Treatment of viruses is carried out in cases where they cause significant discomfort to a person. Apply for example:

• antipyretics, if the temperature is above 37.5 degrees;
• vasoconstrictor drops are used to relieve nasal edema;
• in rare cases, antibiotics (if a bacterial infection has joined);
• NSAIDs that relieve pain and fever, such as aspirin, paracetamol, ibuprofen.

During treatment, doctors recommend drinking more fluids in order to fight intoxication of the body, moderate nutrition, bed rest and humidity in the room of at least 50% where the patient is. Therapy for influenza is no different, but the doctor must be sure to monitor the patient, because this disease can cause serious consequences. One of them is pneumonia, which can lead to pulmonary edema and death.

If such complications have begun, then treatment must necessarily be carried out in a hospital with the use of special medications (Zanamivir, Oseltamivir). When the human papillomavirus is digested, the therapy consists in maintaining immunity in good shape, surgical removal of warts, genital warts. In cases of severe viral pathologies. For example, HIV, a course of antiretroviral drugs is needed. It cannot be completely eliminated, but you can keep it under control and prevent the spread of the disease.

In case of infection with herpes of the genitals, it is necessary to take special drugs, their maximum effectiveness is confirmed in the first 48 hours. If you use the funds later, their medicinal effect is significantly reduced and the course of treatment can last from several weeks to several months. Herpes on the lips should be treated with local remedies (ointments, gels), but even without them, the wound heals within a week.

Antiviral drugs

In medicine, there is a certain number of medicines of this group, which have proven their effectiveness and are used constantly. The entire list of drugs is conventionally divided into two types:

1. Medicines that stimulate human immunity.
2. The drugs that attack the detected virus are direct-acting drugs.

The first group refers to a broad spectrum of drugs, but their use leads to serious complications. One example of such drugs is interferons, and the most popular of them is interferon alpha-2b. It is prescribed for the treatment of chronic forms of Hepatitis B, previously it was prescribed for hepatitis C. Patients could hardly tolerate such therapy, which led to side effects from the central nervous system, cardiovascular system. In some cases, pyrogenic properties are manifested - they cause fever.

The second type of drugs PPD is more effective, easier to tolerate by patients. Among the drugs in demand, the following treatment options are distinguished:

1. Herpes- acyclovir. It helps to overcome the symptoms of the disease, but does not completely kill it.
2. Flu- influenza neuraminidase inhibitors (Zanamivir, Oseltamivir). Modern strains of influenza have developed resistance to previous drugs (adamantanes), and they are not effective. Name of drugs: Relenza, Ingavirin, Tamiflu.
3. Hepatitis... For the treatment of group B viruses, interferons are used together with Ribavirin. For hepatitis C, a new generation of drugs is used - Simeprevir. Its effectiveness reaches 80-91% of a persistent virological response.
4. Hiv... It cannot be completely cured, antiretroviral drugs provide a lasting effect, cause remission, and a person cannot infect others. The therapy is lifelong.

Prophylaxis

Preventive measures may differ slightly depending on the type of virus. For example, to prevent infection with hepatitis or HIV, it is necessary to protect themselves during sexual intercourse. There are two main areas of prevention of viral diseases:

1. Specific... It is carried out to develop specific immunity in humans through vaccination. A person is injected with a weakened strain of the virus so that the body develops antibodies to it. This will help protect you from people with measles, flu, polio, hepatitis (liver disease). Most life-threatening diseases can be prevented with vaccines.
2. Nonspecific... Strengthening human immune defenses, healthy lifestyle, physical activity and normal nutrition. A person must follow the rules of hygiene, which will protect him from intestinal infections, protect himself during sexual intercourse in order to prevent HIV infection.