Viruses are an undeclared war on humanity. Viruses and their characteristics Methods of infection by viruses

Recently, we received a letter from Vladivostok, full of despair, in which an entire family, from grandmother to little Nastya and Kostya, has practically not left the hospital for several months due to an intestinal infection caused by viruses. No nifuroxazides, enterosgels, smects, rehydrons and other drugs, including droppers, solve the problem. Severe vomiting, high fever, muscle and headaches, inflammation of the nasopharynx, lacrimation, photophobia, convulsions, heart pain, rapid pulse, weakness, drowsiness, diarrhea - all this literally haunts and has not let go of this family for a long time. We literally became the last hope for these people, especially after their distant relative from Moscow with similar symptoms was cured by us within one month. People were amazed that “living herbs” managed to cope with the virus!

However, in recent years, trends in the emergence of new diseases have been clearly visible, or “old” diseases are changing so much that it is necessary to carefully improve and modernize their formulation and treatment regimens, for example, as is the case with MRSA - resistant Staphylococcus aureus. The article brought to your attention may provide an answer about the reasons for the emergence of new diseases and viruses.

In mid-April 2009, virus samples from two California children suffering from influenza arrived at the Centers for Disease Control and Prevention in Atlanta (USA) for further study. The doctors saw “something” that did not fit with the normal ideas about those specific strains of influenza that they already knew and had. After careful study and observation, a virus was discovered that had a unique genetic code different from any known human influenza virus. This was a completely new discovery for science.

But at the same time, this event marked the beginning of the 2009 swine flu pandemic. The virus, which may have started infecting people first in Mexico, has spread around the world, infecting millions of people and killing thousands. The pandemic ended by the end of August 2010.

The killer virus was a new strain of H1N1, an influenza virus involved in the 1918 Spanish flu pandemic, which killed 30 to 50 million people worldwide, more than died during World War I, or 2.7 to 5. 3% of the world's population.

Emergency hospitals during the 1918 influenza epidemic.

The emergence of the new H1N1 in 2009 was a reminder to people that despite advances in treating infectious diseases in recent decades, the looming shadow of deadly pandemics remains.

Every appearance of another mysterious virus causes concern and concern among scientists: once in 2002

People on the street wear masks due to the swine flu outbreak.

SARS (atypical pneumonia) in the Chinese province of Guangdong, or in 2009 swine flu that infected many people in Mexico and spread throughout the world, or more recently - 2012 MERS-CoV (Middle East respiratory syndrome - a viral respiratory infection that originated around the Arabian peninsula and killed half of the people who became infected with it; because of this, and also against the background of the growing number of deaths, the Minister of Health of Saudi Arabia was fired).

This 3-D model illustrates a common influenza virus (there are different types). A seasonal respiratory infection, influenza is responsible for three to five million cases of severe illness and an estimated 250,000 to 500,000 deaths, according to the World Health Organization.

Every time another mysterious virus appears, researchers are reminded of the same questions: is this the virus that will cause the next pandemic? Will humanity be able to stop him?

But now, new threatening trends are being added to the existing challenges. These are the latest UN demographic forecasts, according to which the world population will reach 9.6 billion people by mid-century, and 11 billion by 2100.

Eleven billion people. This is the number of people, according to preliminary estimates by the United Nations, that could live on Earth by the end of this century. This is 4 billion more people than are alive today. This is a staggering number compared to just 2.5 billion people who lived in 1950. These 11 billion people will leave a huge imprint on the Earth: they all must eat, they must have enough drinking water; all waste generated from their vital activity can potentially contribute to the spread of diseases; they could affect the planet's already changing climate and many of Earth's animal and plant species.

A huge number of people, their interaction with animals and different ecosystems, an increase in international trade and travel, all these factors will change the life of humanity, which is constantly faced with the problems of preventing and combating epidemics. And this is not a book theory. In fact, the unprecedented growth of the human population in the second half of the last century - growing from 2.5 billion to 6 billion - caused changes, including the emergence of new infections. Researchers have established a link between pandemic risk and population density.

Studying outbreaks of epidemics since the mid-20th century, scientists have discovered that the rate of occurrence of diseases caused by pathogenic microorganisms new to humans is in no way related to progress in diagnostic and surveillance methods, which merely record the dynamics of the emergence of more and more new diseases.

At the Centers for Disease Control and Prevention (CDC), a scientist takes measurements of the amount of H7N9 virus that was grown and collected in the CDC laboratory.

So, between 1940 and 2004, more than 300 new infectious diseases were “recorded”.

Some of these diseases were caused by a pathogen that was present in different species and then in humans - for example, West Nile Virus, SARS coronavirus and HIV.

Coronavirus, the family of viruses to which the common cold belongs, are a group of viruses that have a corona-like (corona) appearance when viewed under an electron microscope.

Others were caused by new pathogens that evolved to negate the effects of available drugs, making diseases such as multidrug-resistant tuberculosis and malaria virtually impossible to treat.

Some pathogens, such as the bacteria that cause Lyme disease, are not new to humans, but their frequency has increased dramatically, perhaps due to changes that newly arrived humans brought with them from the environment of the animal hosts of these pathogens.

Scientists are confident that more and more diseases will arise every year. One of them even joked, saying that if for most people this is something incomprehensible and abstract, then for specialists and researchers it is also completely new and unknown.

Diseases of the future are already waiting for us in nature.

When scientists analyzed the characteristics of the emerging diseases, they found some similarities between them. All known emerging diseases have been associated with sudden population growth, new human activity in the environment, and high wildlife diversity in the area where the pathogen originated. The researchers found that about two-thirds of the new diseases were transmitted to humans from animals.

More than 70% of these diseases are known as zoonotic infections (that is, infectious diseases that affect not only people, but also some species of animals from which humans become infected. A person becomes infected from sick animals either through close contact with them or by consuming food their meat, milk, as well as products made from this milk. In some cases, an infection, for example, anthrax, can be transmitted to a healthy person through objects made from the skin, bristles and hair of sick animals). For example, the Nipah virus, which causes inflammation of the brain and first appeared in 1999 in Perak, Malaysia, or the SARS coronavirus, when both hosts of the virus that infected farmers were bats.

If humans do not frequently come into contact with wildlife, then such pathogens should theoretically pose little risk to humans. But pathogens can attack humans by first infecting other animals, as humans are in contact with, for example, domestic pigs. Animals serve as the middle link in this disease chain, however, they must have been in areas that growing populations had begun to take away from wildlife, or where people rarely, if ever, ventured into such areas.

Scientists say that every region of the wild harbors a whole host of microbes, most of which we know nothing about. By building a road through a new area of ​​tropical forest, creating pig farms there, people come into contact with these pathogens.

The number of pathogens found in wildlife and capable of infecting people has increased over time and especially over the last decade of the 20th century. Such pathogens were responsible for more than half of the new infectious diseases that emerged unexpectedly during this time period.

Human contact with different species of wild animals, during which transmission of new viruses occurs, may increase in the future as the population grows and people seek places to live and build settlements in areas where they live, including close to wildlife.

Prediction of the future.

When the first case of HIV/AIDS was discovered in the United States in 1981, it essentially began another pandemic that continues to this day. HIV is believed to have originated in chimpanzees, infected 60 million people and killed an estimated 30 million.

Over the years, if there was complacency and thought that infectious diseases had been conquered, that was history.

The complacency that was present in the years before HIV largely no longer exists. Scientists are constantly on the lookout for the next pathogen that could cause an epidemic. One of the viruses that scientists suspected was H5N1, a strain of influenza virus that was circulating among birds and killing them. Resources dedicated to preparing for and managing an avian influenza pandemic in humans were transferred and applied to the swine influenza pandemic in 2009.

Another worrisome flu virus on the watch list is H7N9, the bird flu first detected in China in 2013. It infected a number of people who came into contact with infected birds.

How do viruses constantly change, how do they mutate, allowing them to easily spread among people?

Under an electron microscope, a flu virus is in the process of copying itself. Viral nucleoproteins (blue) encapsulate the influenza genome (green). The influenza virus polymerase (orange) reads and copies the genome.

In fact, these are the most difficult questions for scientists to find answers to, not only how viruses living in animals become capable of infecting humans, but also what makes them able to move from person to person.

The H5N1 virus, scientists believe, must undergo four mutations before it can be transmitted through the air among mammals.

Despite efforts to thoroughly study the H5N1 and H7N9 viruses, scientists still do not know how people become infected. The mechanism of infection usually begins to be investigated when the virus has already spread among people.

Scientists have found that in some parts of the world, new viruses have a high chance of “proving” themselves. Tropical Africa, Latin America and Asia, with their great biodiversity and the rapid development of human interaction with the environment, contribute to the activation of viruses that immediately penetrate the human body. And only then, they will be able to follow the human chain to reach any point on the globe.

Epidemics can grow faster and be more costly.

Today, travelers are able to travel distances in a few hours from places that in the past would have taken months to reach. But this is a benefit not only for humans, but also for microbes. Sick travelers can be carriers and carry pathogens to their destination before they even realize they are sick. In the future, population growth and the rapid development of tourism, and this is confirmed by elementary mathematical calculations, will invariably be linked: where there are more tourists, there will be the appearance and growth of epidemics.

The emergence of SARS in China in 2002 provided a clear picture of how a virus can travel when its host is a human using modern travel communications: the virus spread rapidly throughout the world within weeks, infecting more than 8,000 people and killing about 800 before what measures were taken were taken under control and restrictions on travel and quarantine of victims were introduced.

The traveler virus can cause economic losses related to disease treatment and epidemic control. The SARS virus cost billions of dollars by reducing international travel by 50 to 70 percent and hurting businesses in several sectors. Chinese GDP growth fell 2% point in one quarter and half a percentage point in annual growth, according to World Bank data and Chinese government estimates.

Is humanity ready to face the future?

The migration of the world's population from sparsely populated rural areas to densely populated cities may also affect the spread of pathogens. By 2050, 85 percent of people in the developed world and 54 percent in so-called developing countries are expected to leave rural areas for cities.

From a global disease control perspective, urbanization may have some positive aspects. However, this will only happen if an effective surveillance and early warning system can be put in place. Concentrating populations in cities requires a stronger public health sector, as people in crowded cities are often more vulnerable to infectious diseases.

Scientists say a robust public health system is needed to respond to population growth, urbanization, an aging population and increased travel and interactions between humans and animals that lead to the emergence of new diseases.

The only source of optimism is the "tremendous progress" that has been made in reducing the amount of time it takes to get a swine flu vaccine. Less than two months after swine flu became a pandemic in 2009, vaccines were developed and mass produced.

Unfortunately, people nowadays have a false sense of security and are quite careless. After all, although it is possible to eliminate some diseases, the truth is that most new diseases are simply waiting for their time, and some letters in which people turn to us with requests for help, because standard treatment regimens no longer work, only confirm this.

There is no need to say that most infectious diseases are extremely severe. Moreover, viral infections are the most difficult to treat. And this despite the fact that the arsenal of antimicrobial agents is being replenished with more and more new agents. But, despite the achievements of modern pharmacology, true antiviral drugs have not yet been obtained. The difficulties lie in the structural features of viral particles.

These representatives of the vast and diverse kingdom of microorganisms are often mistakenly confused with each other. Meanwhile, bacteria and viruses are fundamentally different from each other. And in the same way, bacterial and viral infections differ from each other, as well as the principles of treating these infections. Although in fairness it is worth noting that at the dawn of the development of microbiology, when the “guilt” of microorganisms in the occurrence of many diseases was proven, all these microorganisms were called viruses. Literally translated from Latin, virus means I. Then, as scientific research progressed, bacteria and viruses were isolated as separate independent forms of microorganisms.

The main feature that distinguishes bacteria from viruses is their cellular structure. Bacteria are essentially single-celled organisms, while viruses have a non-cellular structure. Let us recall that a cell has a cell membrane with cytoplasm (the main substance), a nucleus and organelles located inside - specific intracellular structures that perform various functions in the synthesis, storage and release of certain substances. The nucleus contains DNA (deoxyribonucleic acid) in the form of paired spirally twisted strands (chromosomes), in which genetic information is encoded. Based on DNA, RNA (ribonucleic acid) is synthesized, which, in turn, serves as a kind of matrix for the formation of protein. Thus, with the help of nucleic acids, DNA and RNA, hereditary information is transmitted and protein compounds are synthesized. And these compounds are strictly specific to each type of plant or animal.

True, some single-celled organisms, the most ancient in evolutionary terms, may not have a nucleus, the function of which is performed by a nucleus-like structure - the nucleoid. Such non-nucleated unicellular organisms are called prokaryota. It has been established that many types of bacteria are prokaryotes. And some bacteria can exist without a membrane - the so-called. L-shape. In general, bacteria are represented by many types, between which there are transitional forms. Based on their appearance, bacteria are classified as rods (or bacilli), curved (vibrios), and spherical (cocci). Clusters of cocci may look like a chain (streptococcus) or a bunch of grapes (staphylococcus). Bacteria grow well on carbohydrate and protein nutrient media in vitro (in vitro). And with the correct method of seeding and fixation with certain dyes, they are clearly visible under a microscope.

Viruses

They are not cells, and unlike bacteria, their structure is quite primitive. Although, perhaps, this primitiveness determines virulence - the ability of viruses to penetrate tissue cells and cause pathological changes in them. And the size of the virus is negligible - hundreds of times smaller than bacteria. Therefore, it can only be seen using an electron microscope. Structurally, the virus is 1 or 2 molecules of DNA or RNA. On this basis, viruses are divided into DNA-containing and RNA-containing. As can be seen from this, a viral particle (virion) can easily do without DNA. A DNA or RNA molecule is surrounded by a capsid, a protein shell. This is the entire structure of the virion.

When approaching a cell, viruses attach to its shell, destroying it. Then, through the resulting envelope defect, the virion injects a strand of DNA or RNA into the cell cytoplasm. That's all. After this, viral DNA begins to reproduce many times inside the cell. And each new viral DNA is, in fact, a new virus. After all, the protein inside the cell is synthesized not by the cell, but by the virus. When a cell dies, many virions emerge from it. Each of them, in turn, searches for a host cell. And so on, in geometric progression.

Viruses are present everywhere and everywhere, in places with any climate. There is not a single species of plant or animal that is not susceptible to their invasion. It is believed that viruses were the very first life forms. And if life on Earth ends, then the very last elements of life will also be viruses. It should be noted that each type of virus infects only a certain type of cell. This property is called tropism. For example, encephalitis viruses are tropic to brain tissue, HIV is tropic to the cells of the human immune system, and the hepatitis virus is tropic to liver cells.

Basic principles of treatment of bacterial and viral infections

All microorganisms, bacteria, and viruses are prone to mutation - changing their structure and genetic properties under the influence of external factors, which can be heat, cold, humidity, chemicals, ionizing radiation. Mutations are also caused by antimicrobial drugs. In this case, the mutated microbe becomes immune to the action of antimicrobial drugs. It is this factor that underlies resistance - the resistance of bacteria to the action of antibiotics.

The euphoria that took place several decades ago after penicillin was obtained from mold has long since subsided. And penicillin itself has long retired, having passed the baton in the fight against infection to other, younger and stronger antibiotics. The effect of antibiotics on bacterial cells can be different. Some drugs destroy the bacterial membrane, others inhibit the synthesis of microbial DNA and RNA, and others uncouple the course of complex enzymatic reactions in the bacterial cell. In this regard, antibiotics can have a bactericidal (destroy bacteria) or bacteriostatic (inhibit their growth and suppress reproduction) effect. Of course, the bactericidal effect is more effective than the bacteriostatic one.

What about viruses? On them, as on non-cellular structures, Antibiotics don't work at all!

Then why are antibiotics prescribed for ARVI?

Maybe these are illiterate doctors?

No, the point here is not at all about the professionalism of doctors. The bottom line is that almost any viral infection depletes and suppresses the immune system. As a result, the body becomes susceptible not only to bacteria, but also to viruses. Antibiotics are prescribed as a preventive measure against bacterial infection, which often occurs as a complication of ARVI.

It is noteworthy that viruses mutate much faster than bacteria. This may be due to the fact that there are no true antiviral drugs that can destroy viruses.

But what about Interferon, Acyclovir, Remantadine, and other antiviral drugs? Many of these drugs activate the immune system, and thereby prevent the intracellular penetration of the virion and contribute to its destruction. But a virus that has penetrated a cell is invincible. This largely determines the persistence (hidden asymptomatic course) of many viral infections.

An example is herpes, or more precisely, one of its types, herpes labialis - labial herpes. The fact is that external manifestations in the form of bubbles on the lips are just the tip of the iceberg. In fact, the herpes virus (a distant relative of the smallpox virus) is located in the brain tissue, and penetrates the mucous membrane of the lips through the nerve endings in the presence of provoking factors - mainly hypothermia. The above-mentioned Acyclovir is able to eliminate only the external manifestations of herpes. But the virus itself, once “buried” in the brain tissue, remains there until the end of a person’s life. A similar mechanism is observed in some viral hepatitis and HIV. This explains the difficulties in obtaining medications for the full treatment of these diseases.

But there must be a cure; viral diseases cannot be invincible. After all, humanity was able to overcome the threat of the Middle Ages - smallpox.

Without a doubt, such a cure will be obtained. More precisely, it already exists. His name is human immunity.

Only our immune system can curb the virus. According to clinical observations, the severity of HIV infection has noticeably decreased over 30 years. And if this continues, then in a few decades the frequency of transition of HIV infection to AIDS and subsequent mortality will be high, but not 100%. And then this infection will probably be something like an ordinary, quickly passing disease. But then, most likely, a new dangerous virus will appear, like today’s Ebola virus. After all, the struggle between Man and the Virus, as between the macrocosm and the microcosm, will continue as long as Life exists.

Researching the history of viruses is problematic because they leave no fossils and because of their machinations to copy themselves. To complicate matters, viruses can infect not only people, but also bacteria, algae and even fungi.

But it’s not for nothing that scientists are chilling in their laboratories - they have managed to piece together theories about the origin of viruses. Scientists assumed that viruses like herpes or tonsillitis exchange their properties with the host cell. It can be assumed that viruses were originally like large pieces of DNA and then became independent, or that viruses arose at the dawn of evolution, and some of them remained for a long time in the genomes of cells. The fact that viruses that infect humans and bacteria share common features suggests that they have a common origin, originating roughly several billion years ago. This highlights another problem with tracking the history of viruses: they are made up of many small particles that come from different sources. I would compare the structure of the virus with a modern New Year tree - they are of different colors and shapes, made of different materials, with New Year's toys of infinitely different shapes and colors.

The fact that deadly viruses like Ebola, as well as their distant relatives that cause measles and rabies, can only be found within a limited number of species suggests that these viruses are relatively new; after all, these organisms arose together in recent times. by the standards of evolution. Many of these "new" viruses likely originated in insects many millions of years ago, and at some point in evolution developed the ability to infect other species.

HIV, which first emerged in humans in 1920, is believed to be another type of virus known as a retrovirus. These simple viruses contain related elements found in normal cells, so they have the ability to copy and paste themselves throughout the genome. There are a number of viruses that have a similar self-copying process that alters the normal flow of information in cells ( lat. retro - reverse). Their signature mode of replication may be a bridge between the origins of life on Earth and the life we ​​know now. In fact, among our genes we recognize many “fossilized” retroviruses left over from the infection of distant ancestors. This can help trace our evolution as a species.

1.2 Signs of viruses

To disguise a virus, its actions to infect other programs and cause harm may not always be carried out, but only when certain conditions are met. After the virus performs the actions it needs, it transfers control to the program in which it is located, and its operation for some time does not differ from the operation of an uninfected one. All the actions of the virus can be performed quickly enough and without issuing any messages, so the user often does not notice that the computer is working with “oddities.” Signs of a virus include:

Slowdown of the computer;

Inability to load the operating system;

Frequent freezes and crashes in the computer;

Cessation of work or incorrect operation of previously successfully functioning programs;

Increasing the number of files on disk;

Changing file sizes;

Periodic appearance of inappropriate system messages on the monitor screen;

Reducing the amount of free RAM;

A noticeable increase in hard disk access time;

Changing the date and time of file creation;

Destruction of the file structure (disappearance of files, distortion of directories, etc.);

The floppy drive warning light comes on when you access it.

no appeal.

It should be noted that these symptoms are not necessarily caused by computer viruses, they can be the result of other reasons, so the computer should be periodically diagnosed.

1.3 Classification of viruses

Known software viruses can be classified according to the following criteria:

¨ habitat

¨ method of contamination of the habitat

¨ influence

¨ features of the algorithm

Depending on their habitat, viruses can be divided into:

¨ network

¨ file

¨ boot

¨ file-boot.

Network viruses spread across various computer networks.

File viruses are embedded mainly in executable modules, that is, in files with COM and EXE extensions. They can be embedded in other types of files, but, as a rule, once written in such files, they never gain control and therefore lose the ability to reproduce.

Boot viruses are embedded in the boot sector of the disk (Boot sector) or in the sector containing the system disk boot program (Master Boot Record).

File-boot viruses infect both files and boot sectors of disks.

According to the method of infection, viruses are divided into:

¨ resident

¨ non-resident.

When a resident virus infects (infects) a computer, it leaves its resident part in the RAM, which then intercepts the operating system's access to objects of infection (files, disk boot sectors, etc.) and injects itself into them. Resident viruses reside in memory and are active until the computer is turned off or rebooted.

Non-resident viruses do not infect computer memory and are active for a limited time.

Based on the degree of impact, viruses can be divided into the following types:

¨ harmless, do not interfere with the operation of the computer, but reduce the amount of free RAM and disk memory; the actions of such viruses are manifested in some graphic or sound effects

¨ dangerous viruses that can lead to various problems with your computer

¨ very dangerous, the impact of which can lead to loss of programs, destruction of data, and erasure of information in system areas of the disk.

1.4 Basic measures to protect against viruses

In order to avoid exposing your computer to viruses and to ensure reliable storage of information on disks, you must follow the following rules:

¨ equip your computer with modern antivirus programs, for example NOD32, Doctor Web, and constantly update their versions

¨ before reading information recorded on other computers from floppy disks, always check these floppy disks for viruses by running anti-virus programs

¨ when transferring archived files to your computer, scan them immediately after unzipping them on your hard drive, limiting the scan scope to only newly recorded files

¨ periodically check computer hard drives for viruses by running anti-virus programs to test files, memory and system areas of disks from a write-protected floppy disk, after loading the operating system from a write-protected system floppy disk

¨ always protect floppy disks from writing when working on other computers, if information will not be written to them

¨ be sure to make archival copies of valuable information on floppy disks

¨ do not leave floppy disks in the pocket of drive A when turning on or rebooting the operating system to prevent the computer from becoming infected with boot viruses

¨ use anti-virus programs for input control of all executable files received from computer networks.