Viral diseases - a list of common ailments and the most dangerous viruses. Viral Infection: Symptoms, Signs and Treatment in Adults

There is an opinion that earlier people got sick much less often, but the truth is that without the necessary level of technical progress, it was impossible to identify some viruses and provide treatment for them. Why, even today, having the opportunity to grow artificial organs and having mastered neurosurgery, humanity fails to significantly reduce the list of incurable diseases, moreover, it increases due to the effects of radiation, environmental pollution, poor-quality food, as well as the adaptation of viruses and bacteria to antibiotics.

We have collected the most deadly and persistent of the pathogens and placed them in the ranking the most dangerous viruses in the world for humans, describing the main symptoms, origin and distribution area of ​​each of them. Some have almost been eradicated by vaccination, and some were the main topic of the evening news just a week ago.

10. Influenza A virus subtype H5N1 (avian flu)

It got its name due to the killing of huge flocks of poultry in Southeast Asia, from where it spread throughout the planet. The greatest damage was done to countries with poorly developed medicine or suffering from an influx of migrants. Initially, it affected all types of animals, in addition to humans, but soon got to us. It started like a regular flu, with cough and fever, and was able to take the lives of about half of those infected only because, due to typical cold symptoms, they avoided going to the hospital and sought to solve the problem on their own. The spread was stopped by vaccination, because if the immune system copes with the first hit of the strain, then in the future you lose the chance of becoming infected, with the exception of rare mutations.

9 Luho Fever

On the ninth line of the ranking of the most dangerous viruses for humans in the world is fever, which is not inferior even to Ebola in terms of aggressiveness. The only thing that has prevented an epidemic is a complex method of transmission - exclusively tactile contact. The first victim was a travel agent, followed by her four attending physicians. The main symptoms are heavy bleeding, coma and failure of internal organs, but so far it has not been possible to establish neither the causes of the appearance, nor the ways to deal with the disease, because he is relatively young - less than six months have passed since the discovery.

8. Cercopithecine (monkey) herpes virus B

About 70 percent of macaques are considered carriers of this disease. It is extremely easy to get infected, it is enough to get a scratch, or the saliva of a primate gets on the skin, after which you will show symptoms of herpes simplex. After a few days, the rashes will pass, but there is no way back - herpes B has already settled in the nerve cells, first there will be a cough and runny nose, which will be replaced by tremors and loss of consciousness. In total, 17 cases of human infection were recorded, 15 of which were fatal. The only thing that saves is that it is transmitted by airborne droplets only in monkeys, people need closer contact, which is quite simple to avoid.

7 Dengue Fever

Approximately 50 million people are infected each year Central Africa, which makes it possible to place Dengue fever in the ranking of the most dangerous viruses in the world for humans. There are two types: classic and hemorrhagic, and if the first one can be treated extremely effectively, then the second will leave you with a 50% chance of survival. The vectors are mosquitoes and the bats as well as primates. I am glad that only areas near the equator are favorable conditions for the spread, that is, it is extremely difficult to get sick, being a European.

6. Rabies virus

In the Middle Ages, when diagnostics in medicine was only in its infancy, it was assumed that a person was possessed by demons, hence the name came from, although in practice this is an extremely aggressive form of inflammation of the brain, which first disrupts the functioning of the nervous system, clouding the mind, and then finishes it off by refusing internal organs. Everyone, without exception, is vaccinated against rabies at an early age, which significantly increases the effectiveness of treatment after bites from infected animals, but it is still worth contacting the nearest hospital immediately. In general, the prognosis is positive, but if you delay it, then after 8 days you can already be on your deathbed.

5. H1N1 virus (Spanish)

The number of victims of this disease, which originated in Spain and immediately covered about half of its population, without even passing the royal family, was twice as large as the bloodiest war in human history. The worst thing is that there was no cure for the disease as such, recovery depended on the strength of the immunity of each individual person, his diet and hygiene standards. The name arose during the First World War, where the leading bloody battles of the country decided to avoid news of the epidemic, and neutral Spain decided on this desperate step, thereby allowing its citizens to take necessary measures precautions, but still lost one and a half percent of the total population. In some cities, gravediggers died so often that people organized mass graves on their own.

4 Ebola

West Africa in 2014 riveted the attention of the world community, because an extremely rare, but almost always lethal virus raged there. After an outbreak that claimed the lives of about 15 thousand people, the World Health Organization recognized it as a global threat and began searching for a vaccine, which to this day has not been successful, which is extremely regrettable, because in the case of a response to treatment with antiviral drugs within 7 days after infection , the chances of survival are only 4%. In Europe, Ebola has not become widespread due to the high level of medical care, water filtration and a significant distance from natural foci of distribution. This virus was first detected in the Ebola River region (Democratic Republic of the Congo), 12 years ago, where the first victims of the disease were recorded.

3. Smallpox virus

Fortunately, the third most dangerous virus for humans in the world was completely eradicated three decades ago, although its manifestations have been recorded in the literature since the time of Alexander the Great. But in 1964, a worldwide smallpox vaccination campaign was launched, and by the end of the eighties, the disease was completely defeated. The last victim was one of the laboratory assistants in the United States in May 1978. The fact is that someone did not pay due attention to ventilation, and the room in which she worked was not properly ventilated. Recall that there is no cure for this virus today, and death from smallpox occurs just a few days after infection. Smallpox spread around the world during the era of the slave trade, when it was brought from Africa.

2. Marburg hemorrhagic fever

Very similar to Ebola, but much more treatable. Gates to the body are the mucous membranes of the nose and eyes, as well as small wounds. It all starts with a sharp rise in temperature, then comes cirrhosis of the liver and disruption of the nervous system. It is with the appearance of neuralgic symptoms that the greatest mortality is observed, people lose consciousness and no longer come to their senses. Mortality ranges from 50 to 90 percent. The body of Marburg, who died of fever, poses a biological hazard even three months after burial. The problem is also the possibility of an asymptomatic course of fever for the first few days, which significantly reduces the chances of a positive outcome of treatment.

1. HIV virus (AIDS)

The most dangerous to humans in the world continues to take millions of lives every year. The first victims among the population of civilized countries were homosexuals and drug addicts, which for a long time diverted attention from his research, spreading the erroneous assumption that it was lifestyle that led to such a significant deterioration in the functioning of the immune system. In 2008, French scientists received a Nobel Prize for the discovery of the human immunodeficiency virus, and in 2015, for the first time, a child born to an HIV-positive mother was completely cured of AIDS. Unfortunately, for our country, the epidemic of this virus is gaining momentum in the Yekaterinburg region, and total infected in the country is about 1 million 100 thousand people. Therefore, try to avoid questionable sexual relations, drug use and trust only those beauty salons that comply with the standards of sterilization of instruments.

non-cellular infectious agent. It has a genome (DNA or RNA), but is deprived of its own synthesizing apparatus. Able to reproduce, only getting into the cells of more highly organized creatures. Reproducing, damages the cells in which this process occurs.

Each of us is faced with viruses many times in life. After all, they are the cause of most cases of seasonal colds. With the usual ARVI, the body successfully copes on its own - our immunity steadfastly withstands the blows of infections. But not all viral diseases are so harmless. On the contrary, some of them can lead to serious damage to tissues and systems, cause severe chronic diseases, cause disability and even death. How to understand the diversity of viruses? How to protect yourself from the most dangerous? And what if the disease is already detected? What are antibodies to the virus and which ones appear during the illness?

Human viruses

To date, more than 5,000 different viruses have been described, but it is estimated that there are millions of their species. They are found in all ecosystems and are considered the most numerous biological form. At the same time, these infectious agents are capable of infecting animals and plants, bacteria, and even archaea. Human viruses occupy a special place, because they cause the greatest number of diseases. Moreover, diseases are very diverse in their severity, prognosis and course.

At the same time, it is with viruses that an important condition of evolution is associated - horizontal gene transfer, in which the genetic material is transferred not to descendants, but to other types of organisms. In fact, the virus has provided a great deal of genetic diversity. For example, studies have shown that 6-7% of the human genome consists of various virus-like elements and their particles.

virus in men

Human viruses are capable of equally infecting the organisms of children and adults, as well as representatives of both sexes. However, there are species that pose a particular danger to a certain category of the population. An example of a dangerous virus in men is paramyxovirus, which causes mumps. Most often, the mumps passes without any complications, with a noticeable lesion of the salivary and parotid glands. However, the virus in men poses a great danger, because more often than in women, it also affects the sex glands, and in 68% of cases it can cause orchitis - inflammation of the testicles. And this, in turn, can lead to infertility. This complication is typical for adults and adolescents; in boys under 6 years of age, orchitis occurs only in 2% of cases. Also, the virus in men can provoke the development of prostatitis.

Paramyxovirus is highly contagious, transmitted by airborne droplets, including during the incubation period, when there are no symptoms of the disease yet. There is no specific treatment for mumps, so the best protection against the disease is vaccination. The mumps vaccine is included in the mandatory routine vaccination calendar in many countries.

virus in women

Now special attention is focused on the human papillomavirus in women, because some of its species have been proven to be associated with the development of cervical cancer. In total, there are at least 13 such types, according to the World Health Organization, however greatest danger represent types 16 and 18, which are characterized by the highest oncological risk. It is with these two viruses in the body that 70% of all cases of cervical cancer and precancerous conditions are associated.

At the same time, with timely diagnosis and removal of papillomas, this outcome can be avoided. Cancer, as a complication of HPV, develops within 15-20 years with normal immunity, so systematic examinations by a gynecologist will help to identify a dangerous virus in women of different ages in time. It should be said that such a factor as smoking affects the activity of the papillomavirus - it contributes to the degeneration of genital warts into a malignant neoplasm. Since there is no specific treatment for HPV, World Organization Health recommends vaccination against types 16 and 18.

Viruses are especially dangerous in women during pregnancy, because due to their small size they easily penetrate the placental barrier. At the same time, the severity of the course of the disease in the mother and the likelihood of damage to the fetus are not related. It often happens that latent or easily transferred viral infections cause serious pathologies in the fetus, can cause miscarriage.

It should be said that most viruses are dangerous only if a woman becomes infected with them during pregnancy. In this case, the mother's body does not have time to develop enough antibodies to protect the fetus, and the virus causes serious damage.

The most dangerous early pregnancy, up to 12 weeks, because it is now that embryonic tissues are being formed, which are most easily affected by viruses. In the future, the risk of developing complications decreases.

Viruses transmitted through the blood and its components, as well as other biological fluids, are also dangerous directly during childbirth. Since the child can become infected with them, passing through the birth canal.

The most dangerous viruses in women during pregnancy:

• Rubella virus.

In the first trimester of pregnancy, the probability of fetal damage is 80%. After 16 weeks, the risk of damage is significantly reduced, and most often pathologies are manifested only by deafness. In the early stages, the virus can cause bone damage, deformity, blindness, heart defects, and brain damage in the fetus.

• Herpes virus 1st (HSV-1) and 2nd (HSV-2) types.

The most dangerous is the second, genital type, with which a child can become infected during the passage of the birth canal. In this case, the development of severe neurological damage is possible, among which encephalitis is the most dangerous. In some cases, the herpes virus type 2 can lead to the death of a child. HSV-1 is asymptomatic, most often easily tolerated by the fetus and does not cause significant harm to health.

Mother's infection early term can lead to the development of fetal pathologies that are incompatible with life, resulting in a miscarriage. In addition, the disease is dangerous not only by the influence of the virus itself, but also by general intoxication of the body. It, in turn, can cause fetal hypoxia, developmental delay and other things. That is why WHO recommends that pregnant women get vaccinated against influenza, especially during epidemics. dangerous period.

Botkin's disease (hepatitis A) is very often transferred in childhood, so it is quite rare during pregnancy. However, if infection does occur, the disease will proceed in a severe form. Hepatitis B and C can pose a threat to the unborn child, especially if a woman has contracted them during pregnancy. Chronic hepatitis B and C are dangerous infection during childbirth. Most often, it is the hepatitis B virus that is transmitted in this way. Moreover, in the congenital form, it is treated much more difficult and in 90% of cases it passes into a chronic incurable form. Therefore, women planning a pregnancy may be recommended to be vaccinated against hepatitis B. If there is a chronic infection, then it is worth doing cesarean section. The hepatitis E virus is rarely a serious danger, but it is during pregnancy that it can lead to serious consequences for the fetus and the woman herself. Including cause death from kidney failure.

Most often, infection occurs in childhood, after which the person is a carrier of the virus, while no symptoms appear. Therefore, as a rule, by the time of pregnancy, this virus in women does not pose a particular danger. In the event that infection with cytomegalovirus occurred during the bearing of a child, the fetus in 7% of cases can receive complications in the form of cerebral palsy, hearing loss, etc.

The human body develops specific immunity to various viruses that it encounters throughout life. This explains the fact that a child suffers from SARS (acute respiratory viral infections) more often than an adult. The frequency of virus infection in different ages the same, but in an adult, the immune system suppresses the infectious agent even before the onset of symptoms. In domestic pediatrics, there is the concept of "frequently ill child", that is, one that suffers more than 5 SARS per year. However, foreign doctors believe that for children under 3 years old, the norm is 6 infections per year. And a child visiting Kindergarten, can carry up to 10 colds annually. If SARS pass without complications, they should not cause concern, - the well-known pediatrician Yevgeny Komarovsky also believes so.

Also, childhood is characterized by a number of certain viral infections that are extremely rare in adults. Among them:

• Chickenpox.
• Measles.
• Rubella.
• Mumps.

At the same time, it should be noted that children of the first year of life are practically not susceptible to these diseases, since even in the womb they receive antibodies to viruses from the mother's blood through the placenta.

Despite the fact that these infections are most often easily tolerated by children, there is still a risk of complications. For example, measles often leads to pneumonia and is one of the main causes of child mortality, and mumps causes inflammation in the genitals. Therefore, there are effective vaccinations against all of the above viral infections - timely immunization makes it possible to receive immunity without a previous illness.

Virus as a form of life

Also, these non-cellular infectious agents, which is how viruses are now characterized, lack basic and energy metabolism. They cannot synthesize protein, as other living organisms do, and outside the cell they behave like a particle of a biopolymer, and not a microorganism. A virus outside of a cell is called a virion. This is a structurally complete viral particle that is capable of infecting the host cell. When infected, the virion is activated, forms a “virus-cell” complex, and it is in this state that it is able to multiply, while transferring its genetic code to new virions.

Viruses, like other living organisms, are able to evolve through natural selection. It is due to this that some of them, such as the influenza virus, are able to constantly cause epidemics, since the developed immunity against new forms does not work.

The size of the virion is 20-300 nm. Thus, viruses are the smallest infectious agents. For comparison, bacteria are on average 0.5-5 microns in size.

As already mentioned, the virus differs in that it can multiply and is active only inside a living cell. Most types of viruses completely penetrate the cell, but there are also those that introduce only their genome into it.

The life cycle of this extracellular agent can be divided into several stages:

• Attachment.

Moreover, it is at this stage that the range of hosts of the virus is determined, because often these are highly specialized microorganisms that are able to interact only with certain types cells. Thus, viruses that cause respiratory diseases prefer cells of the mucous membranes of the respiratory tract, and HIV is able to interact only with a specific type of human leukocytes.

• Penetration.

At this stage, the virus delivers its genetic material inside the cell, which will later be used to create new virions. Viruses can replicate in different parts cells, some use the cytoplasm for these purposes, others use the nucleus.

• Replication is the reproduction of copies of the genetic material of a virus.

This process is possible only inside the cell.

• The release of virions from the host cell.

In this case, the membrane and cell wall are damaged, and the cell itself dies. However, in some cases, viruses remain in the cell without damaging it and multiply with it. Infected cells can exist for a long time, and the disease itself does not make itself felt, turning into a chronic form. This behavior is typical, for example, for the herpes virus, papillomavirus and others.

Virus genome: DNA-containing and RNA-containing

Depending on the form in which the genetic material of viruses is contained, they are usually divided into DNA-containing and RNA-containing (Baltimore classification).

• DNA containing viruses.

Their replication (reproduction) occurs in the cell nucleus, and the process of formation of new virions in most cases is fully provided by the synthetic apparatus of the cell.

• RNA viruses.

A large group that mainly multiplies in the cytoplasm of the cell. Among RNA-containing agents, one should separately mention retroviruses, which differ from others in that they are able to integrate into the DNA of the host cell. These viruses are often separated into a separate group for their unique property reverse transcription. During normal genome replication, information passes from DNA to RNA, and retroviruses are able to make double-stranded DNA based on single-stranded RNA.

Depending on how active the virus is and how destructive the genetic material is for the cell, its effect on it also depends. For example, one of the most dangerous infections, HIV, is classified as a retrovirus. On the other hand, it was precisely this integration into the genome of a living cell that allowed some types of this type of virus to gain a foothold in DNA - scientists associate the species diversity of living organisms, as well as evolutionary processes, with them.

Types of viruses

Viruses, despite their small size and dependence on the cell, are still able to protect the genetic material they carry. It is for this, first of all, that the shells of the virus are responsible. Therefore, sometimes viruses are classified precisely according to their types.

Compared to other infectious agents, the structure of viruses is quite simple:

• Nucleic acid (RNA or DNA).
• Protein coat (capsid).
• Shell (supercapsid). It does not occur in all types of viruses.

Virus capsid

The outer shell consists of proteins and performs a protective function of the genetic material. It is the capsid that determines which types of cells the virion can attach to, the shell is also responsible for initial stages cell infection - membrane rupture and penetration.

The structural unit of the capsid is the capsomere. While in the cell, the virus by self-assembly reproduces not only the genetic material, but also a suitable protein shell.

In total, 4 types of capsids are distinguished, which are easy to distinguish by shape:

• Spiral - capsomeres of the same type surround single-stranded DNA or RNA of the virus along their entire length.
• Icosahedral - capsids with icosahedral symmetry, which sometimes resemble balls. This is the most common type of virus that can infect animal cells, and therefore infect humans.
• Oblong - one of the subspecies of the icosahedral capsid, but in this version it is slightly elongated along the line of symmetry.
• Complex - includes spiral and icosahedral type. Occurs rarely.

Virus shell

Some types of viruses, for additional protection, surround themselves with another shell formed from the cell membrane. And if the capsid is formed inside the cell, then the supercapsid "captures" the virus, leaving the cell.

The presence of an envelope, essentially consisting of material related to the body, makes the virus less visible to the human immune system. This means that such vibrios are highly contagious, able to stay in the body longer than others like them. Examples of enveloped virions are HIV and the influenza virus.

Virus infection

Signs of the presence of a virus in the body are highly dependent on its type. Some infections cause an acute course of the disease, pronounced characteristic symptoms. These include the influenza virus, measles, rubella. Others, on the contrary, may not appear long years while harming the body. This is how the hepatitis C virus, HIV and other dangerous infections behave. Sometimes their presence can only be detected by specific blood tests.

Expert opinion

“Our body can fully live and develop only if there is a constant exchange of substances between it and the environment. One of the most important forms of communication between the body and environment is the connection through respiratory system. The upper respiratory tract (URT) is the first protective barrier against infectious pathogens, including viruses. It is the mucous membrane of the upper respiratory tract with its ciliated epithelium that is the morphofunctional substrate on which the inflammatory process of ARVI is played out.

It has been proven that in most cases, viruses enter the body through the nasopharyngeal mucosa, since it can be injured due to the formation of microcracks (dry air, the use of vasoconstrictors, etc.).

Of particular relevance is the reparative action of Derinat, aimed at restoring the integrity of the epithelium of the respiratory tract. Regeneration is the replacement of damaged cells with cells of the same type.

The reparative effect is necessary:

1. The reparative effect is necessary to strengthen the protective properties of the mucosa and prevent infection.
2. The reparative effect is necessary to prevent secondary bacterial complications.
3. The reparative effect is necessary to speed up recovery and prevent re-infection.

The more pronounced the reparative effect, the faster the full-fledged epithelium is restored, the faster and easier the recovery and return to healthy life!

* "Immune and reparative therapy of acute respiratory infections in children" H.S. Khaertynov, S.M. Kushnir

Methods of infection with viruses

Since viruses are widespread and able to infect different cells human body, all the main ways of transmission of infection are available to them:

• Airborne (airborne) - viruses are carried through the air, when coughing, sneezing, or even just talking.

This route of transmission is typical for all SARS, including influenza, as well as measles, rubella and other infections.

• Alimentary (fecal-oral) - the route of transmission, characteristic of the types of viruses that can accumulate in the intestines, excreted with feces, urine, and vomiting.

Infection occurs through dirty water, poorly washed food, or dirty hands. Examples are hepatitis A and E, poliomyelitis. Often, such infections are characterized by a seasonal nature - infection with the virus occurs in warm weather, in summer.

• Hematogenous (through blood and components) - the infection enters through wounds, microcracks in the skin.

Viruses transmitted in this way are dangerous in blood transfusions, surgical intervention and other medical manipulations, injection drug addiction, tattooing and even cosmetic procedures. Often, the infection is able to penetrate through other biological fluids - saliva, mucus, and so on. Hepatitis B, C and D viruses, HIV, rabies and others are transmitted through the blood.

• Transmissible - transmitted through the bites of insects and ticks.

Among the most common diseases caused by such viruses are encephalitis and mosquito fever.

• Vertical - the virus is transmitted from mother to child during pregnancy or childbirth.

Most diseases with hematogenous transmission can be transmitted in this way. In the first trimester of pregnancy, rubella, influenza and other diseases are dangerous.

• Sexual - infection occurs through unprotected sexual contact.

The route of transmission is also characteristic of viruses transmitted through blood and components. According to WHO, four viral infections are most often transmitted in this way - HIV, herpes, papillomavirus, hepatitis B.

Not all viruses that enter the human body are capable of causing disease. Any foreign organism that comes to us immediately meets with the cells of the immune system. And if a person has developed acquired immunity, then the antigens will be destroyed even before the symptoms of the disease have developed. Our immune system gives stable protection, often for life, to many viruses - acquired immunity is developed after contact with the virus (illness, vaccination).

Some infections, such as measles, rubella, poliomyelitis, can cause epidemics among children and practically do not affect the adult population. This is precisely due to the presence of acquired immunity. Moreover, if “herd immunity” is provided with the help of vaccination, such viruses will not be able to cause epidemics in children's groups.

Some species, such as the influenza virus, can mutate. That is, every season a new strain of the virus appears, for which the population has not developed immunity. Therefore, it is this infection that can cause annual epidemics and even pandemics - infection of the population of several countries or regions.

Among the most famous pandemics that humanity has experienced, different strains of influenza are quite common. This is, first of all, the "Spanish flu" of 1918-1919, which claimed 40-50 million lives, and the Asian flu of 1957-1958, during which approximately 70 thousand people died.

Smallpox viruses have also caused pandemics, causing between 300 and 500 million deaths in the 20th century alone. Thanks to mass vaccination and revaccination, this virus was defeated - the last case of infection was recorded in 1977.

Human immunodeficiency virus (HIV), which is also equivalent to a pandemic disease in terms of prevalence, causes serious concern.

Symptoms of the entry of the virus into the body

Different viruses in the body behave differently, manifest their symptoms, and sometimes the disease is asymptomatic, without making itself felt for a long time. For example, hepatitis C most often does not manifest itself by external signs, and the disease is detected only in an advanced stage or by chance - according to blood tests. Influenza, on the contrary, always proceeds acutely, with fever, general intoxication of the body. For measles and rubella, a specific rash on the skin is characteristic.

There are viruses that are successfully suppressed by the immune system, but remain in the body. A classic example is herpes simplex, infection with which is lifelong and incurable. However, the disease rarely causes serious inconvenience, manifesting itself only occasionally as ulcers on the lips, genitals and mucous membranes.

Many types of human papillomavirus occur with subtle symptoms, the infection does not require treatment and goes away on its own. However, there are HPVs that form that can degenerate into malignant neoplasms. Therefore, the appearance of any type of papilloma or warts is an occasion to take a virus test, which will help determine the type of infection.

Signs of a viral infection

Most often, we are faced with viruses that cause acute respiratory infections. And here it is important to be able to distinguish them from diseases caused by bacteria, since the treatment in this case will be very different. SARS provoke more than 200 types of viruses, including rhinovirus, adenovirus, parainfluenza and others. However, despite this, infection with the virus is still manifested by similar symptoms. SARS is characterized by:

• Low subfebrile temperature (up to 37.5 ° C).
• Rhinitis and cough with clear mucus.
• Headaches, general weakness, poor appetite are possible.

Influenza is distinguished by special symptoms, which always begins acutely, within a few hours, is characterized by high fever, as well as general intoxication of the body - severe malaise, pain, often in muscles and joints. Human viruses that cause respiratory diseases are usually active in the body for no more than a week. And this means that approximately on the 3rd-5th day after the first symptoms, the patient feels a significant improvement in his condition.

A bacterial infection causes high fever, sore throat, and chest, the discharge becomes greenish, yellow, thicker, blood impurities may be observed. The immune system does not always successfully cope with bacteria, so there may not be improvement in the first week of illness. Bacterial diseases of the respiratory tract can cause complications in the heart, lungs and other organs, so their treatment should be started as soon as possible.

It is extremely difficult to identify the virus only by symptoms. This is especially true for types of viruses that are similar in effect on the body. For example, about 80 human papillomaviruses have been studied to date. Some of them are quite safe, others lead to the development of cancer. Hepatitis viruses, despite the fact that they affect the same organ, the liver, represent different threat. Hepatitis A often passes without complications, and virus C, on the contrary, in 55-85%, according to WHO, leads to the development of a chronic disease ending in cancer or cirrhosis of the liver. Therefore, if symptoms are detected or if infection is suspected, tests should be taken to help accurately determine the type of virus.

Virus analysis

Among the tests that are used to detect viruses, the most popular are:

• ELISA blood test.

It is used to detect antigens and antibodies to them. At the same time, there is both a qualitative (determining the presence of a virus) and a quantitative (determining the number of virions) analysis. Also, this method will help determine the level of hormones, identify sexually transmitted infections, allergens, etc.

• Serological blood test.

It is used not only to determine an infectious disease, but also to establish its stage.

• Polymerase chain reaction (PCR method).

To date, the most accurate method that helps to identify even small fragments of foreign genetic material in the blood. Moreover, since this analysis for viruses determines the presence of the pathogen, and not the reaction to it (detection of antibodies), it can be carried out even in the incubation period of the disease, when there is still no noticeable immune response.

To diagnose viral infections, it is important to determine not only the infection itself, but also its amount in the blood. This is the so-called viral load - the amount of a particular type of virus in a certain volume of blood. It is thanks to this indicator that doctors determine the infectiousness of a person, the stage of the disease, they can control the treatment process and check its effectiveness.

After the virus enters the human body, the immune system begins to produce specific immunoglobulins (Ig) - antibodies to a specific type of virus. It is by them that one can often reliably determine a specific disease, the stage of the disease, and even the presence of a previous infection.

In humans, there are five classes of antibodies - IgG, IgA, IgM, IgD, IgE. However, in the analysis for the virus, two indicators are most often used:

• IgM are immunoglobulins that are produced first when an infection occurs. That is why their presence in the blood indicates an acute stage of a viral infection. IgM is produced throughout the course of the disease, during initial infection or exacerbation. These are rather large immunoglobulins, which, for example, cannot pass through the placental barrier. This explains the serious damage to the fetus by some viruses during the primary infection of a woman during pregnancy.
• IgG - antibodies to the virus, which are produced much later, in some diseases already at the stage of recovery. These immunoglobulins are able to remain in the blood for life and thus provide immunity against a particular virus.

Analyzes for antibodies should be deciphered as follows:

• IgM and IgG are absent. There is no immunity, the person has not encountered an infection, which means that primary infection is possible. When planning a pregnancy, such indicators for certain viruses in women mean a risk group for the development of a primary infection. In this case, vaccination is recommended.
• IgM absent, IgG present. The body has developed immunity to a specific virus.
• IgM is present, IgG is absent. There is an acute stage of infection, the virus is in the body for the first time.
• IgM and IgG are present. The end of the disease, or exacerbation of a chronic process. The correct interpretation of such a virus test result depends on the amount of antibodies and can only be done by a doctor.

Types of viral infections

Viruses, like other antigens, cause an immune response - this is how the body copes with various foreign objects and microorganisms. However, some types of viruses are able to remain invisible to the immune system for a long time. It depends on this how long the disease will last, whether it will become chronic, and what harm it can cause to the body.

Any viral disease begins with an acute stage. However, in some cases, recovery occurs after it, and in others, the disease becomes chronic. Moreover, many diseases prone to chronicity are extremely weakly manifested in the acute period. Their symptoms are nonspecific, and sometimes completely absent. On the contrary, those diseases that the immune system successfully suppresses are characterized by severe symptoms.

Acute viral infections that do not become chronic include:

• SARS, including influenza
• Rubella
• Mumps
• Hepatitis A (Botkin's disease) and E
• Rotavirus infection (intestinal flu)
• chicken pox

To the listed viruses in the human body, a strong immunity is developed. Therefore, diseases are transferred only once in a lifetime. The only exceptions are some forms of SARS, in particular, influenza, the virus of which actively mutates.

Chronic viral infections

A considerable number of viruses are characterized by a chronic course. Moreover, in some cases, if a virus is detected, then after the acute stage, the person remains its lifelong carrier. That is, the infection does not pose a danger to human health and life. These viruses include:

• Epstein-Barr virus (in rare cases, can cause infectious mononucleosis).
• Some types of human papillomavirus.
• Herpes simplex virus types 1 and 2.

All these viruses are potentially capable of causing quite serious damage to tissues and systems, but only in the case when immunity is significantly reduced. For example, with AIDS, certain autoimmune diseases, as well as when taking certain medications, in particular, in the treatment of oncological lesions.

Another group of viruses that can remain in the human body for life is dangerous even for people with a normally functioning immune system. Among the main infections of this kind:

• AIDS virus.

The period of infection and the first stage of the spread of the virus throughout the body are asymptomatic. However, 2-15 years after infection, a person develops acquired immunodeficiency syndrome (AIDS). It is the syndrome that is the cause of death among HIV-infected people.

• Hepatitis C and B.

Hepatitis C in the acute stage is asymptomatic, and often (up to 85%) becomes chronic, which threatens with serious complications in the form of cancer or cirrhosis of the liver. However, today there are drugs that effectively cure patients. Hepatitis B becomes chronic much less frequently, in no more than 10% of cases in adults. At the same time, there are no drugs for this virus - chronic hepatitis B is not treated.

• Human papillomavirus with a high oncological risk (types 16, 18 and others).

Some types of HPV are capable of provoking the development of malignant tumors, in particular, it is the human papillomavirus in women that causes 70% of all cases of cervical cancer. The virus in men can also be manifested by the formation of warts of various types, but does not cause oncological diseases.

To date, medicine has made significant progress in the treatment of viral infections, but this group of diseases is difficult to treat. In most cases, there are simply no effective drugs, and the treatment of viruses is reduced to symptomatic and supportive therapy.

What to do if a virus is found

The treatment strategy is determined by which virus is detected. For example, if we are talking about SARS, childhood viral diseases (measles, rubella, mumps, roseola children), effective therapy will be the removal of symptoms. And only if they cause significant discomfort. So, for example, you can use:

• Vasoconstrictor drops to relieve swelling in the nasal cavity.
• Antipyretic at high temperature (from 37.5-38 ° C).
• Non-steroidal anti-inflammatory drugs that have a dual effect - lower the temperature and relieve pain (ibuprofen, paracetamol, aspirin).

The treatment of the influenza virus does not differ from the described scheme, however, since it is this infection that often causes severe complications, the patient must be under the supervision of a doctor. One of the most dangerous consequences is viral pneumonia, which develops on the 2-3rd day after the onset of the disease and can cause pulmonary edema and death. Such inflammation of the lungs is treated exclusively in a hospital with the use of specific drugs (Oseltamivir and Zanamivir).

If human papillomavirus is detected, treatment is limited to supportive care and surgical removal of genital warts and warts.

With hepatitis C in the chronic stage in modern medicine direct-acting antiviral drugs (DAAs) are used. It is these drugs that WHO recommends today as an alternative to interferons and Ribavirin, with which the disease was treated until recently.

People with HIV are treated with antiretroviral drugs. If a virus is found in the body, it cannot be completely eliminated, but with treatment it is possible to control it and also prevent the spread of the disease.

With an exacerbation of a herpes infection, special drugs can be taken, but they are effective only in the first 48 hours after the onset of symptoms. Their use later is impractical.

The basis of the fight against viruses in the body is the human immune system. It is he who provides a successful cure for most known viruses, while others are able to neutralize and make safe.

The immune system is quite complex and multi-stage. It is divided into innate and acquired immunity. The first provides non-specific protection, that is, it acts on all foreign objects in the same way. The acquired one appears after the immune system encounters a virus. As a result, specific protection is developed that is effective in the case of a specific infection.

At the same time, some viruses in one way or another are able to resist the defense system and not cause an immune response. A prime example is HIV that infects the cells of the immune system itself, these viruses are successfully isolated from them and block the production of antibodies.

Another example is neurotropic viruses that infect the cells of the nervous system, and the immune system simply cannot get to them. These infections include rabies and polio.

innate immunity

Innate immunity is the reaction of the body to any foreign biomaterial that occurs upon first contact with an infection. The reaction develops very quickly, however, unlike acquired immunity, this system recognizes the type of antigen worse.

Innate immunity can be divided into components:

• Cellular immunity.

For the most part, it is provided by phagocyte cells capable of absorbing the virus, infected dying or dead cells. Phagocytosis is an important component of post-infection immunity. In fact, it is phagocytes that are responsible for the effective cleansing of the body from foreign objects.

• Humonal immunity.

An important protective reaction to viral diseases is the body's ability to produce a specific protein - interferon. The affected cell begins to produce it as soon as the virus begins to multiply in it. Interferon is released from the infected cell and comes into contact with neighboring, healthy cells. The protein itself has no effect on the virus, so infectious agents cannot develop protection against it. However, it is interferon that can change unaffected cells in such a way that they suppress the synthesis of viral proteins, their assembly, and even the release of virions. As a result, the cells become immune to the virus, preventing it from multiplying and spreading throughout the body.

acquired immunity

Acquired immunity is the ability to neutralize antigens that have already entered the body before. There are active and passive types of innate immunity. The first is formed after the body encounters a virus or bacterium. The second is transmitted to the fetus or infant from the mother. Through the placenta during pregnancy and with breast milk during feeding, antibodies from the mother's blood get to the child. Passive immunity provides protection for several months, active - often for life.

Acquired immunity, like innate immunity, can be divided into:

• Cellular immunity.

It is provided by T-lymphocytes (a subspecies of leukocytes) - cells that can recognize viral fragments, attack them and destroy them.

• Humonal immunity.

The ability of B-lymphocytes to produce antibodies to the virus (immunoglobulins), which neutralize specific antigens, allows you to create specific body defenses. An important function of humoral immunity is the ability to remember contact with an antigen. For this, specific IgG antibodies are produced, which in the future are able to prevent the development of the disease if a virus infection occurs.

To date, medicine is used relatively a large number of antiviral drugs with proven efficacy. The entire spectrum of drugs can be divided into two groups:

1. Stimulating the human immune system.
2. Acting directly on the detected virus, the so-called direct-acting drugs.

The former can be called broad-spectrum drugs, but their treatment often has a number of serious complications. One of these drugs are interferons. The most popular of them is interferon alfa-2b, which is used in the treatment of chronic forms of hepatitis B and was previously used for the hepatitis C virus. Interferons are quite difficult to tolerate by patients, often causing various side effects from the side of the cardiovascular and central nervous system. They also impose pyrogenic properties - cause fever.

The second group of antiviral drugs is more effective and easier to tolerate by patients. Among them, the most popular medicines that treat:

• Herpes (drug Acyclovir).

Suppress the symptoms of a viral disease, but cannot completely eliminate the virus.

• Flu.

According to WHO recommendations, influenza neuraminidase inhibitors (oseltamivir and zanamivir) are now being used, since most modern strains of the influenza virus have resistance to their predecessors, adamantium. The commercial names of the drugs are Tamiflu and Relenza.

• Hepatitis.

Until recently, Ribavirin in combination with interferons was actively used to treat hepatitis C and B. Hepatitis C (genotype 1B) is currently being treated with a new generation of drugs. In particular, since 2013, the direct-acting drug Simeprevir has been approved, which showed high efficiency - 80-91% of a persistent virological response in different groups, including 60-80% in people with liver cirrhosis.

Unfortunately, drugs cannot completely eliminate the virus, but antiretroviral drugs give a fairly stable effect - a remission stage sets in, and the person becomes non-infectious to others. For HIV-positive people, antiretroviral therapy should be lifelong.

Prevention of viral diseases

Since there is no specific treatment for many viral diseases, but at the same time they pose a very real danger to human health and life, prevention comes to the fore.

Precautionary measures

Many viral infections spread quickly and are highly contagious. When it comes to airborne viruses, an effective measure is the introduction of quarantine in preschool and school institutions. Since an infected child can spread the virus even before symptoms appear, this is how the entire community can be prevented from infecting the virus.

In an epidemically dangerous period, it is advisable to avoid large crowds of people, especially in enclosed spaces. This will reduce the risk of infection with various acute respiratory viral infections, including influenza.

Prevention of viruses transmitted by the faecal-oral route (for example, Botkin's disease and polio) - washing hands, boiling water and using only proven sources of water, thoroughly washing fruits and vegetables.

The most dangerous are viruses transmitted through blood and other body fluids. Risk factors for infection for them are:

• injection drug addiction.
• Cosmetic procedures and tattooing using non-disinfected instruments.
• Use of personal hygiene items of an infected person - nail scissors, Toothbrush, razor and more.
• Unprotected sex.
• Surgery, blood transfusion.

A person at risk for infection with such diseases must be tested for antibodies to viruses, primarily HIV, hepatitis C and B. Blood must be donated 4-5 weeks after the alleged infection.

Any precautionary measures do not give a 100% guarantee of protection against viruses. To date, the most reasonable way to prevent viral infections is vaccination.

Pharmacists have developed vaccines that are effective against more than 30 different viruses. Among them:

• Measles.
• Rubella.
• Mumps.
• Chickenpox.
• Flu.
• Polio.
• Hepatitis B.
• Hepatitis A.
• Human papillomavirus 16 and 18 types.

It was with the help of mass vaccination that it was possible to defeat two smallpox viruses that caused epidemics and led to death and disability.

Beginning in 1988, WHO, in partnership with a number of public and private health sectors, launched the Global Polio Eradication Initiative. To date, it is through mass immunization that the number of cases of virus infection has been reduced by 99%. As of 2016, polio is endemic (that is, one that does not spread outside the country) in only two countries - Afghanistan and Pakistan.

Vaccines use:

• Live but weakened microorganisms.
• Inactivated - killed viruses.
• Acellular - purified material, such as proteins or other parts of an antigen.
• synthetic components.

In order to reduce the risk of complications, vaccination for some viruses takes place in several stages - first with inactivated material, and then with live material.

Some vaccines give immunity for life - resistant antibodies to the virus are produced. Others require revaccination - re-vaccination after a certain time.

Viruses and diseases

Human viruses cause diseases of varying severity and course. Some of them are faced by most of the inhabitants of the earth, others are rare. In this section, we have collected the most famous viruses.

Adenovirus

Adenovirus was discovered in 1953, then it was discovered after surgery on the tonsils and adenoids. Today, about 50-80 subspecies of this virus are known to science, and all of them cause similar diseases. It is adenovirus that is a common cause of the development of acute respiratory viral infections, and in some cases can lead to intestinal diseases in children. Infection with the virus leads to damage to the cells of the mucous membranes of the upper respiratory tract, tonsils, eyes, bronchi.

• transmission path.

Airborne (more than 90% of cases), fecal-oral.

• Virus symptoms.

The disease begins with a high temperature, which can rise to 38 ° C. General intoxication appears - chills, pain in muscles, joints, temples, weakness. There is redness of the throat and inflammation of the mucous membrane of the larynx, as well as rhinitis. With eye damage - redness of the mucous membranes, itching, pain.

• Possible complications.

They rarely appear, a bacterial infection can join, which will cause pneumonia, otitis, sinusitis.

• Treatment.

Symptomatic, the use of vitamins, antihistamines is acceptable.

• Forecast.

Favorable, in the absence of concomitant diseases and immunodeficiency, the disease goes away on its own.

The influenza virus is perhaps the most well-known of all infections that cause damage to the respiratory tract. It really differs from other acute respiratory viral infections both in terms of symptoms and possible complications.

It is the flu that often causes epidemics and pandemics, as the virus constantly mutates. At the same time, some strains can lead to quite serious illnesses, often fatal. Every year, even in the absence of serious pandemics, according to WHO, from 250 thousand to 500 thousand people die in the world.

• transmission path.

Airborne, the virus can also persist on the surfaces and hands of an infected person.

• Virus symptoms.

It always starts acutely - the temperature rises (sometimes up to 39 ° C), cough and rhinitis begin, and the general condition worsens. The influenza virus causes severe intoxication of the body, which manifests itself in pain, general weakness, drowsiness, loss of appetite.

• Possible complications.

Influenza more often than other SARS leads to complications, most of which are associated with the addition of a bacterial infection - pneumonia, bronchitis, otitis media, sinusitis and other diseases. Intoxication leads to exacerbation of chronic diseases, including cardiovascular, diabetes, asthma. Influenza can also cause viral complications, which will appear on the 2-3rd day after the first symptoms. These are the most dangerous consequences diseases, as they can lead to pulmonary edema, the development of encephalitis and meningitis. Temporary loss of hearing or smell is possible.

• Treatment.

At normal flow disease, the detected virus does not need specific treatment. With the development of viral complications, especially pneumonia, the drugs Oseltamivir and Zanamivir are used, the introduction of interferons is possible.

• Forecast.

Influenza poses the greatest danger to people over 65 years of age, as well as those who have concomitant diseases - diabetes, heart and lung diseases. It is among these categories that the virus most often leads to death. Also, infection with the influenza virus can be dangerous for pregnant women and children. Therefore, for people at risk, WHO recommends annual vaccination.

Varicella (chickenpox) is caused by the human herpesvirus type 3 from the large family of herpesviruses. This disease is typical for young children, the person who has undergone it receives immunity to the virus for life. In this case, the susceptibility of the organism is 100%. Therefore, if a person without acquired immunity comes into contact with a sick person, he will definitely become infected. In adulthood, chickenpox can be more difficult to tolerate, and if the primary infection occurs in a pregnant woman, it can cause serious damage to the fetus (however, in a maximum of 2% of cases).

• transmission path.

Airborne, while the virus is able to move with air current at distances up to 20 m.

• Virus symptoms.

Home hallmark chickenpox is a specific vesicular rash that spreads throughout the body, occurs on the mucous membranes. After the first symptoms, new blisters form for another 2-5 days, in rare cases up to 9 days. They itch and itch. The onset of the disease is accompanied by high fever, especially difficult in adults.

• Possible complications.

AT childhood chickenpox is tolerated quite easily, the infection goes away on its own without specific treatment. Special attention rash should be given, because if you comb it on the skin, a scar can form. Also, bursting blisters and ulcers that have arisen in their place can be an entrance for a bacterial infection of the skin.

• Treatment.

There is no specific treatment, with chickenpox treatment is symptomatic, in particular, prevention of skin infection is carried out. An effective vaccine has now been developed against the virus, which provides lifelong immunity.

• Forecast.

Favorable.

herpes simplex virus

The herpes simplex virus is of two types. The first type most often causes ulcers on the lips and mucous membranes of the mouth. The second is damage to the genital organs. A person infected with the herpes virus remains its carrier for life. This infection cannot be cured, but with normal immunity, it can be asymptomatic. HSV refers to neurotropic viruses, that is, after infection, it moves to the nerve cells and there remains inaccessible to the immune system.

The greatest danger is HSV-2, since, according to WHO, it increases the risk of infection with the human immunodeficiency virus by 3 times.

• transmission path.

HSV-1 is transmitted through oral contact, with saliva, during an exacerbation of the infection. HSV-2 is transmitted sexually and vertically.

• Virus symptoms.

HSV-1 is manifested from time to time by the formation of ulcers on the lips and mucous membranes. The frequency of such rashes depends on the person's immunity; in some cases, the carrier may not show the virus at all. HSV-2 is also often asymptomatic, sometimes manifested by rashes in the form of vesicles on the genitals and in the anal area.

• Possible complications.

The type 2 virus is most dangerous in women during pregnancy, as it can cause infection of the fetus and subsequent pathologies from the central nervous system and other organs.

• Treatment.

During exacerbations, an infected person may be recommended the use of antiherpetic drugs, such as acyclovir.

• Forecast.

In the absence of immunodeficiency, this infection does not lead to serious health problems.

The group of papillomaviruses combines more than 100 types of various extracellular agents. Although they cause illnesses that are similar in symptoms - skin growths appear - the severity of the course of the disease depends on the type of infection, as well as the immune system of the infected person.

human papillomavirus

Human papillomaviruses (HPV) are one of the most common infections in the world that can cause various lesions. Most species are harmless, show mild symptoms after infection and subsequently resolve without treatment. According to WHO, 90% are completely cured within 2 years after infection.

However, the human papillomavirus is still under special control and is being studied in detail. This is due to the fact that today it has been proven that at least 13 types of human papillomavirus can cause cancer. First of all, types 16 and 18 are dangerous.

• transmission path.

Contact (through the skin with neoplasm), sexual (for genital forms of the virus).

• Virus symptoms.

After infection, papillomas, warts and various warts form on the skin or mucous membranes. Depending on the type of HPV, they look different and occur in different parts of the body. So, for example, some types (1, 2, 4) are characterized by damage to the feet, the oral mucosa is attacked by viruses of types 13 and 32. Condylomas on the genitals occur under the influence of 6, 11, 16, 18 and other types.

• Possible complications.

The most dangerous complication is the degeneration of papilloma into a malignant tumor.

• Treatment.

There is no specific therapy. Viruses either go away on their own or remain for life. People with severe symptoms are recommended surgical removal of warts, genital warts and papillomas.

• Forecast.

Generally favorable. Even high-risk HPV types can be controlled. The key to successful suppression of the human papillomavirus in women and men is timely diagnosis, which involves blood tests for antibodies.

Human papillomavirus in women

Some types of human papillomavirus in women have been shown to be associated with the development of cervical cancer. According to WHO, types 16 and 18 cause 70% of all cases of this cancer.

At the same time, it takes an average of 15-20 years for the degeneration of a neoplasm, if a woman has no problems with immunity. For HIV-infected people, this interval can be up to 5 years. Local treatment can help prevent the development of infection, and timely diagnosis is necessary for this. That is why women are recommended to undergo annual examinations by a gynecologist and be tested for papillomaviruses.

On the genitals, two types of genital warts develop - genital and flat. The former most often provoke types of the virus 6 and 11. They are clearly visible, form on the external genital organs, and rarely lead to cancer. Flat ones are provoked by viruses of types 16 and 18. They are located on the internal genital organs, are less visible and have a high oncological risk.

Today, vaccines have been developed from HPV 16 and 18, which WHO recommends using at the age of 9-13 years. In the US and some European countries, these vaccinations are included in the vaccination schedule.

Among all inflammations of the liver, diseases of a viral nature are most common. There are such types of hepatitis viruses - A, B, C, D and E. They differ in the mode of transmission, the course of the disease and the prognosis.

Hepatitis A and E

Viruses of this group differ from the rest in that they are not capable of causing a chronic disease. Once transferred disease in the vast majority of cases gives lifelong immunity. Therefore, Botkin's disease is characteristic of childhood.

• transmission path.

Alimentary (fecal-oral), most often through contaminated water.

• Virus symptoms.

Hepatitis A and E is manifested by nausea, vomiting, pain in the liver, fever, loss of appetite. Darkening of the urine and whitish feces are also characteristic. The disease includes an icteric period, in which, due to an increase in the level of bilirubin in the blood, the skin, mucous membranes, nail plates and sclera of the eyes acquire a yellow tint.

• Possible complications.

These inflammations of the liver are dangerous for people with immunodeficiency, as well as during pregnancy. When infected with the virus during pregnancy, hepatitis A is much more difficult to carry, and hepatitis E can cause serious fetal pathologies and, in some cases, death of the mother.

• Treatment.

There is no specific treatment for hepatitis A and E viruses. The main therapy is supportive agents, as well as compliance therapeutic diet. A vaccine has been developed for hepatitis A.

• Forecast.

Favorable. Hepatitis A and E viruses do not cause chronic disease. The infection goes away without treatment after a few weeks or months. In the future, the liver is able to fully recover.

Hepatitis B, C, D

Hepatitis B, C and D are a major health hazard. They are prone to chronicity, especially type C, which leads to chronic disease in 55-85% of cases. The hepatitis D virus is of particular concern. This is a satellite virus, that is, one that is active only in the presence of virus B. It is he who significantly aggravates the course of the disease. And in some cases, coinfection leads to acute liver failure and lethal outcome already in the acute phase of the disease.

• transmission path.

Hematogenous (through the blood), sexual, vertical. Hepatitis B, sometimes referred to as serum hepatitis, is especially contagious.

• Symptoms.

Hepatitis B is acute with severe symptoms of liver damage - intoxication, nausea, loss of appetite, white feces, dark urine, jaundice. Hepatitis C in the acute stage in the vast majority of cases is asymptomatic. Moreover, it can remain invisible in a chronic form. A person guesses about the disease only at the critical stages of cirrhosis or liver cancer.

• Possible complications.

Both diseases can turn into chronic infections. Most often this happens in the case of the hepatitis C virus. The chronicity of hepatitis B depends on the age of the patient. So, for example, in infants, the probability of such a course is 80-90%, and for adults - less than 5%. Chronic hepatitis is dangerous with irreversible liver damage - cirrhosis, cancer, acute liver failure.

• Treatment.

Hepatitis B is treated in the acute period; in the chronic form, there is no specific therapy - lifelong maintenance medications are prescribed. However, there is an effective vaccine against the B virus that has been used since 1982. Modern pharmacological developments have made it possible to increase the percentage of the effectiveness of the treatment of chronic hepatitis C up to 90%. Currently, direct-acting antiviral drugs are used for this disease, which are taken for 12 weeks.

• Forecast.

Chronic hepatitis C can cause severe liver damage up to 20 years after infection, in some cases up to 5-7 years. The risk of developing cirrhosis is 15-30%. Hepatitis B is dangerous already in the acute period if the D virus is also present in the blood. Chronic form hepatitis B can also cause serious liver damage.

Human Immunodeficiency Virus (HIV)

HIV is now considered one of the most dangerous infections in the world. It is ubiquitous, with approximately 37 million infected people worldwide as of 2014. HIV is a pandemic disease that differs from others in that it affects the immune system itself. The virus is most dangerous in the final stage of the development of the disease - with acquired immunodeficiency syndrome (AIDS). It is with such a diagnosis that other infections can become more active in a person, a tendency to form malignant tumors appears, any minor illness gives serious complications. It is a strong decrease in immunity that is the cause of death from HIV.

• transmission path.

Hematogenous, sexual.

• Symptoms.

Before the development of AIDS, it is asymptomatic. After that, manifestations of reduced immunity appear, in particular, viruses are activated, which practically do not manifest themselves in a healthy person. For example, the Epstein-Barr virus, cytomegalovirus. Other viruses (measles, rubella, influenza,) lead to serious lesions and the development of pathologies.

• Possible complications.

Associated with infections that a person has. With immunodeficiency, the risk of developing complications in any disease sometimes reaches 100%. Even some mild infections can be fatal.

• Treatment.

HIV cannot be completely cured. If a person becomes infected, the infection will remain with him for life. However, effective antiretroviral therapy has been developed and should be lifelong. Thanks to these drugs, HIV can be kept under control, preventing the development of AIDS. The viral load is reduced enough that a person receiving treatment is no longer contagious.

• Forecast.

With timely treatment, HIV-positive people are able to live a full life. Without treatment, AIDS develops within 2-15 years and leads to the death of the patient.

Cytomegalovirus infection is often remembered in the context of diseases dangerous during pregnancy. It is for the fetus that this virus from the herpesvirus family can pose a serious threat. However, this happens only if a woman becomes infected during the period of bearing a child. This happens quite rarely, because most of the population is faced with the virus in childhood.

• transmission path.

Through biological fluids - saliva, urine, semen, secretions, as well as through breast milk.

• Virus symptoms.

In people without immunodeficiency, even in the acute period, it is asymptomatic. The fetus may develop various pathologies, in particular deafness. Primary infection with cytomegalovirus during pregnancy can lead to miscarriage.

• Possible complications.

Extremely rare and only for risk groups.

• Treatment.

A vaccine has been developed against cytomegalovirus, which may be necessary for people with immunodeficiency, pregnant women without acquired immunity to the virus.

• Forecast.

Favorable.

Rabies virus

The rabies virus is a neurotropic virus, that is, one that can infect nerve cells. Being in the nervous system, it becomes inaccessible to the cells of the immune system, since the immune response acts only within the bloodstream. That is why infection with rabies without treatment is fatal.

• transmission path.

Through the bites and saliva of infected animals. Most often transmitted from dogs.

• Virus symptoms.

After an incubation period, which lasts an average of 1-3 months, there is a slight increase in temperature, pain at the bite site, and insomnia. Later, convulsions, light and hydrophobia, hallucinations, a sense of fear, aggression appear. The disease ends with muscle paralysis and respiratory disorders.

• Possible complications.

If symptoms appear, then rabies leads to death.

• Treatment.

Immediately after a bite or possible contact with a rabid animal, vaccination should begin. Treatment of the rabies virus consists of a course of post-exposure prophylaxis (PEP).

• Forecast.

Favorable with timely vaccination.

Poliomyelitis mainly affects children under 5 years of age. In most cases, it does not cause serious health effects, but 1 in 200 infected with the virus leads to severe paralysis. In 5-10% of patients with complications, paralysis of the respiratory muscles also occurs, which leads to death.

Poliomyelitis is now virtually eradicated by vaccination. The disease has remained endemic in two countries, Pakistan and Afghanistan.

• transmission path.

Fecal-oral.

• Virus symptoms.

In the paralytic form of the course of the disease, the body temperature rises, a runny nose, nausea, and headache appear. Paralysis can develop within a few hours, most often affecting the limbs.

• Possible complications.

Muscle atrophy, torso deformity, persistent paralysis of the limbs that remain for life.

• Treatment.

There is no specific treatment. At the same time, vaccination against polio completely eliminates the risk of infection.

• Forecast.

Due to the immunization of the population, the number of pathologies caused by poliomyelitis has decreased by 99% since 1988.

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 man and animals. Below is a list of the ten most dangerous viruses to humans.

10. Hantaviruses

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.

9. Influenza virus

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).

8. Marburg virus

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 commonly the liver. Marburg fever is one of the ten deadliest diseases transmitted from animals.

7. Rotavirus

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.

6. Ebola virus

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.

5. Dengue virus

Dengue virus is one of the most dangerous viruses for humans, causing dengue fever in severe cases, which has 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.

4. Smallpox virus

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 famous case infection was registered on October 26, 1977 in the Somali city of Marka.

3. Rabies virus

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, bad dream, patients become aggressive, violent, hallucinations, delirium, a feeling of fear appear, paralysis of the eye muscles, lower extremities, paralytic respiratory disorders and death soon set in. The first signs of the disease occur late, when destructive processes have already occurred in the brain (edema, hemorrhage, degradation 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.

2. Lassa virus

The 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.

1. AIDS virus

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 mucous membranes or blood with 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 their reproduction speed, capable of initiating and killing certain types of cells. Without medical intervention average duration the life of a person infected with the immunodeficiency virus is 9-11 years. According to 2011 data, 60 million people worldwide have become ill with HIV infection, of which: 25 million have died, and 35 million continue to live with the virus.

Name

Pathogen

Affected areas of the body

Distribution method

Type of vaccination

Microvirus of one of three types - A, B and C - with varying degrees of virulence

Respiratory tract: epithelium lining the trachea and bronchi.

drip infection

Killed virus: The strain of the killed virus must match the strain of the virus disease-causing

Cold

Variety viruses, most commonly rhinoviruses (RNA-containing viruses)

Respiratory tract: usually upper only

drip infection

Live or inactivated virus is administered by intramuscular injection; vaccination is not very effective as there are many different strains of rhinoviruses

Variola virus (DNA-containing virus), one of the smallpox viruses

Respiratory tract, then skin

Droplet infection (possible contagious transmission through wounds on the skin).

Live attenuated (attenuated) virus is introduced into a scratch on the skin; currently not applicable.

Mumps (mumps)

Respiratory tract, then generalized infection throughout the body through the blood; especially affected salivary glands, and in adult males also the testes

Droplet infection (or contagious transmission through the mouth with infectious saliva)

Live attenuated virus

Xovirus (RNA-containing virus)

Respiratory tract (from oral cavity to the bronchi), then passes to the skin and intestines

drip infection

Live attenuated virus

Measles rubella (rubella)

rubella virus

Respiratory tract, cervical lymph nodes, eyes and skin

drip infection

Live attenuated virus

Polio (infantile paralysis)

Poliomyelitis virus (picornavirus; RNA-containing virus, three strains are known)

Throat and intestines, then blood; sometimes motor neurons of the spinal cord, then paralysis can occur

Droplet infection or through human feces

Live attenuated virus is administered orally, usually on a sugar cube

Yellow fever

Arbovirus, i.e. arthropod-borne virus (RNA containing virus)

The lining of blood vessels and the liver

Carriers - arthropods, such as ticks, mosquitoes

Live attenuated virus (it is also very important to control the number of possible carriers)

Influenza is not such a serious disease, but many millions of people get sick every year, and periodically there are pandemics (general epidemics) that take many lives.

In 1886 and 1887 influenza was registered in Russia; in the summer of 1889 in Bukhara, the activity of the pathogen increased, and later that year the infection spread to other regions of Russia and Western Europe. Thus began the flu pandemic of 1889-1890. During the second and third epidemics, the number deaths increased progressively. The most ominous feature of this epidemic was that it apparently gave impetus to some process, and now the flu is not parting with us, or, as the epidemiologist Greenwood wrote, "we can never regain lost ground."

In 1918, after the end of the First World War, an unprecedented flu pandemic broke out, called the "Spanish flu".

In a year and a half, the pandemic has swept all countries, hitting more than a billion people. The disease proceeded exceptionally hard: about 25 million people died - more than from injuries on all fronts of the First World War in four years.

Never before has influenza caused such a high mortality rate: mortality has been low during all subsequent epidemics and pandemics, although the percentage of deaths from influenza is low, the mass nature of the disease leads to the fact that during each large epidemic of influenza, thousands of patients die from it, especially the elderly and children. It has been noted that during epidemics, mortality from diseases of the lungs, heart and blood vessels rises sharply.

Influenza remains the "king" of epidemics. No disease can affect hundreds of millions of people in a short time, and more than a billion people fall ill with the flu during a pandemic! This was the case not only in the memorable pandemic of 1918, but relatively recently - in 1957, when the "Asian" flu pandemic broke out, and in 1968, when the "Hong Kong" flu appeared. Several varieties of the influenza virus are known - A, B, C, and others; under the influence of environmental factors, their number may increase. Due to the fact that immunity in influenza is short-term and specific, it is possible to get sick multiple times in one season. According to statistics, an average of 20-35% of the population gets the flu every year.

The source of infection is a sick person; patients with a mild form, as spreaders of the virus, are the most dangerous, since they do not isolate themselves in a timely manner - they go to work, use public transport, and visit spectacular places.

The infection is transmitted from a sick person to a healthy person by airborne droplets when talking, sneezing, coughing, or through household items.

Smallpox is one of the oldest diseases. A description of smallpox was found in the Egyptian papyrus of Amenophis Y, compiled 4000 BC. Smallpox lesions were preserved on the skin of a mummy buried in Egypt 3000 BC. The mention of smallpox, which the Chinese called "poison from the mother's breast", is contained in the oldest Chinese source - the treatise "Cheu-Cheufa" (1120 BC). The first classical description of smallpox was given by the Arab physician Rhazes.

Smallpox was the most common and most dangerous disease in the past. Its devastating power was not inferior to the power of the plague.

The first mention of smallpox in Russia dates back to the 4th century. In 1610, the infection was brought to Siberia, where a third of the local population died out. People fled to the forests of the tundra and the mountains set up idols, burned scars on their faces like pockmarks in order to deceive this evil spirit- everything was in vain, nothing could stop the ruthless killer.

However, attempts to protect against smallpox are as old as smallpox itself. They were based on the observation that people who once had smallpox never got sick again.

The first vaccination against smallpox in Russia was carried out in a solemn atmosphere by a professor at Moscow University, Efrem Mukhin, in 1801. A child from an orphanage in Moscow was vaccinated with smallpox using the Jenner method, and in honor of this, the surname Vaccinov was given.

April 10, 1919 V.I. Lenin signed a decree on mandatory smallpox vaccination, which marked the beginning of mass vaccinations.

Poliomyelitis is a viral disease that affects the gray matter of the central nervous system. The causative agent of poliomyelitis is a small virus that does not have an outer shell and contains RNA. The polio virus infects the limbs, that is, it changes the shape of the bones. Characteristic bone changes were found during excavations in Greenland on skeletons dating back to 500-600 BC. The incidence of poliomyelitis is characterized by a number of characteristic features. Poliomyelitis spreads like an intestinal disease. With a high level of sanitation, children do not become infected at an early age, but become infected later. Poliomyelitis, as it were, matures, and in adults the disease is much more severe. An effective method of combating this disease is a live polio vaccine. The use of a polyvaccine made it possible to effectively extinguish outbreaks of the infection epidemic, and the incidence of the disease has sharply decreased. However, vaccination with a live vaccine is not the elimination of the killer virus, but only its replacement with an artificial laboratory strain that is safe for humans.

Rabies is an infectious disease that is transmitted to humans from an infected animal by the bite or contact with the saliva of an infected animal, most commonly a dog. One of the main signs of developing rabies is rabies, when the patient has difficulty swallowing liquids, convulsions develop when trying to drink water. The rabies virus contains RNA, packed in a nucleocapsid of helical symmetry, covered with a shell and, when multiplying in brain cells, forms specific inclusions, according to some researchers, “graveyards of viruses” called Babes-Negri bodies. The disease is incurable.

Tumor viruses - In the years since the occurrence of viral sarcomas in chickens was first established, numerous researchers have different types In vertebrates, oncogenic viruses belonging to two groups have been found: DNA-containing and retroviruses. Among the oncogenic DNA viruses are pacoviruses, adecoviruses, and herpesviruses. Of the RNA viruses, only retroviruses cause tumors.

The range of tumors caused by oncogenic viruses is unusually wide. Although the polyoma virus mainly causes tumors of the salivary glands, its very name indicates that it can cause many other tumors. Retroviruses cause mainly leukemias and sarcomas, which are often the cause of tumors of the breast and a number of other organs. Although cancer is a disease of the whole organism, an essentially analogous phenomenon called transformation is also observed in cell cultures. Such systems are used as models for the study of oncogenic viruses. The ability to transform cells in vitro underlies the methods for the quantitative determination of many oncogenic viruses. The same systems are also used for comparative study of the physiology of normal and tumor cells.

Viruses and Human Cancers - One of the arguments against the role of viruses in most human cancers is the fact that in the vast majority of cases, malignant tumors are not contagious, while with a viral etiology, person-to-person transmission can be expected. If, however, we assume that the activation of inherited viruses plays a role in the occurrence of tumors exogenous factors, it should be expected that the facts of hereditary predisposition to malignant tumors will be revealed. Such a predisposition to the development of some tumors has indeed been found, but various explanations can be found for this. Despite 10 years of intensive work directed by special government programs, the relationship between human cancers and viruses is still problematic. Represented in the highest degree it is strange that oncogenic viruses, which play such an obvious role in the occurrence of tumors in a wide variety of animals, should somehow “bypass” humans.

AIDS - Acquired Immune Deficiency Syndrome - is a new infectious disease that experts recognize as the first truly global epidemic in the known history of mankind. Neither plague, nor smallpox, nor cholera are precedents, since AIDS is decidedly unlike any of these and other known human diseases. The plague claimed tens of thousands of lives in the regions where the epidemic broke out, but never covered the entire planet at once. In addition, some people, having been ill, survived, acquiring immunity and took on the work of caring for the sick and restoring the affected economy. AIDS is not a rare disease that only a few people can accidentally suffer from. Leading experts now define AIDS as a “global health crisis”, as the first truly all-terrestrial and unprecedented epidemic of an infectious disease that is still not controlled by medicine after the first decade of the epidemic, and every infected person dies from it.

AIDS by 1991 was registered in all countries of the world, except Albania. In the most developed country in the world, the United States, already at that time one of every 100-200 people was infected, another resident of the United States was infected every 13 seconds, and by the end of 1991, AIDS in this country came in third in terms of mortality, overtaking cancer. So far, AIDS is forced to recognize itself as a fatal disease in 100% of cases.

The first people with AIDS were identified in 1981. During the past decade, the virus-causative agent spread mainly among certain groups of the population, which were called risk groups. These are drug addicts, prostitutes, homosexuals, patients with congenital hemophilia (since the life of the latter depends on the systematic administration of drugs and donated blood).

However, by the end of the first decade of the epidemic, WHO had accumulated material indicating that the AIDS virus had gone beyond the named risk groups. He entered the general population.

Since 1992, the second decade of the pandemic began. It is expected that it will be significantly heavier than the first. In Africa, for example, in the next 7-10 years, 25% of agricultural farms will be left without a labor force due to extinction from AIDS alone.

AIDS is one of the most important and tragic problems facing humanity at the end of the 20th century. The causative agent of AIDS, the human immunodeficiency virus (HIV), is a retrovirus. Retroviruses owe their name to an unusual enzyme - reverse transcriptase (retrovertase), which is encoded in their genome and allows you to synthesize DNA on an RNA template. Thus, HIV is able to produce in host cells, such as "helper" T-4 - human lymphocytes, DNA copies of its genome. Viral DNA is included in the genome of lymphocytes, where its location creates the conditions for the development of chronic infection. Until now, even theoretical approaches to solving such a problem as cleaning the genetic apparatus of human cells from alien (in particular, viral) information are unknown. Without a solution to this problem, there will be no complete victory over AIDS.

Although it is already clear that the human immunodeficiency virus (HIV) is the cause of acquired immunodeficiency syndrome (AIDS) and related diseases, the origin of this virus remains a mystery. There is strong serological evidence that infection appeared on the west and east coasts of the United States in the mid-1970s. However, cases of AIDS-associated diseases known in central Africa indicate that the infection may have appeared there even earlier (50-70 years). Be that as it may, it has not yet been possible to satisfactorily explain where this infection came from. Several human and simian retroviruses have been discovered using modern cell culture techniques. Like other RNA viruses, they are potentially variable; therefore, they are quite likely to have such changes in the spectrum of hosts and virulence that could explain the emergence of a new pathogen (there are several hypotheses: 1) the impact on a pre-existing virus of unfavorable factors of environmental factors; 2) bacteriological weapons; 3) mutation of the virus as a result of the radiation exposure of uranium deposits in the supposed homeland of the infectious pathogen - Zambia and Zaire).