Viruses are non-cellular infectious agents that have a genome (DNA and RNA), but are not gifted with a synthesizing apparatus. To reproduce, these microorganisms need cells of more highly organized organisms. Once in the cells, they begin to multiply, causing the development of various diseases. Each virus has a specific mechanism of action on its host. Sometimes a person does not even suspect that they are a virus carrier, since the virus does not harm he alth, this condition is known as latency, such as herpes.
To prevent viral diseases, it is important to maintain a he althy lifestyle, strengthen the body's defenses.
Origin and structure
There are several hypotheses about the origin of viruses. Science offers a version of the origin of viruses from fragments of RNA and DNA that were released from a large organism.
The regression hypothesis states that viruses are parasitic organisms with small cells that replicate in largerspecies, but during the period of evolution they lost the genes required for the parasitic form of survival.
Coevolution suggests that viruses appeared simultaneously with living cells as a result of the construction of complex sets of nucleic acids and proteins.
Questions about the structure of the virus, how it reproduces and is transmitted, are studied by a special section of microbiology - virology.
Each viral particle has genetic information (RNA or DNA) and a protein membrane (capsid) that acts as a defense.
Viruses come in different shapes, ranging from simple helical to icosahedral. The standard value is approximately 1/100 of the size of an average bacterium. However, most viruses are very small, making them difficult to examine under a microscope.
Is living matter a virus?
There are two definitions of life forms of viruses. According to the first, extracellular agents are a collection of organic molecules. The second definition states that viruses are a special form of life. It is impossible to answer the question of what viruses exist, specifically and definitively, since biology assumes the constant emergence of new species. They are similar to living cells in that they have a special set of genes and evolve according to the way the natural set. They require a host cell to exist. The lack of one's own metabolism makes it impossible to reproduce without outside help.
Modern science has developed a version according to whichcertain bacteriophages have their own immunity, capable of adaptation. This is proof that viruses are a form of life.
Viral diseases - what is it?
Diseases caused by viruses are mainly manifested as a result of the weakening of the immune system and the rise in temperature, when a favorable state is formed for human viral diseases to develop further after the penetration of pathogenic microelements. Diseases develop as a result of the penetration of viruses into the cells of the human body, when they begin to actively multiply, parasitizing on different areas of the body, using them as a nutrient substrate. Viruses, as a result of their vital activity, cause cell death, which precedes the manifestation of clinical symptoms of the disease.
Viruses of the plant world
If you ask yourself what viruses are, then, in addition to viruses that are dangerous to the human body, you can distinguish a special type of viruses that infect plants. They are not dangerous to humans or animals, as they can only reproduce in plant cells.
The plant world can be protected from pathogenic microorganisms with the help of a resistance gene. Often, plants affected by the virus begin to synthesize substances that destroy parasitic agents (NO, salicylic acid). The danger of these viruses is that they affect the yield.
Artificial viruses
Artificial viruses are created to produce vaccines against infections. Notthe list of what viruses are in the arsenal of medicine created artificially is completely known. However, it is safe to say that the creation of an artificial virus can have a lot of consequences.
Get such a virus by introducing into the cell an artificial gene that carries the information necessary for the formation of new types.
Viruses that infect the human body
What viruses are on the list of extracellular agents dangerous to humans and causing irreversible changes? Here is the aspect of studying modern science.
The simplest viral disease is the common cold. But against the background of a weakened immune system, viruses can cause quite serious pathologies. Each pathogenic microorganism affects the organism of its host in a certain way. Some viruses can live in the human body for years without causing harm (latency).
Certain latent species are even beneficial to humans, as their presence generates an immune response against bacterial pathogens. Some infections are chronic or lifelong, which is purely individual and due to the protective ability of the virus carrier.
Spread of viruses
Transmission of viral infections in humans is possible from person to person or from mother to baby. The rate of transmission or epidemiological status depends on the population density of the area, the weather and season, and the quality of medicine. You can prevent the spread of viral pathologies if you clarify in a timely manner what virus is nowfixed in most patients, and take appropriate preventive measures.
Views
Viral diseases manifest themselves in absolutely different ways, which is associated with the type of extracellular agent that caused the disease, with the place of localization, with the rate of development of the pathology. Human viruses are classified as lethal and indolent. The latter are dangerous because the symptoms are unexpressed or weak, and it is not possible to quickly detect the problem. During this time, the pathogenic organism can multiply and cause serious complications.
The following is a list of the main types of human viruses. It allows you to clarify which viruses are and which pathogenic microorganisms cause diseases that are dangerous to he alth:
- Orthomyxoviruses. This includes all types of influenza viruses. Special tests will help to find out which influenza virus caused the pathological condition.
- Adenoviruses and rhinoviruses. They affect the respiratory system, cause SARS. Symptoms of the disease are similar to influenza, and can cause serious complications such as pneumonia, bronchitis.
- Herpesviruses. Activated against the background of reduced immunity.
- Meningitis. Pathology is caused by meningococci. The mucous membrane of the brain is affected, the nutrient substrate for the pathogenic organism is the cerebrospinal fluid.
- Encephalitis. It has a negative effect on the lining of the brain, causing irreversible changes in the central nervous system.
- Parvovirus. The diseases caused by this virus are very dangerous. The patient has convulsions, inflammationspinal cord, paralysis.
- Picornaviruses. Cause hepatitis.
- Orthomyxoviruses. They provoke parotitis, measles, parainfluenza.
- Rotavirus. Extracellular agent causes enteritis, intestinal flu, gastroenteritis.
- Rhabdoviruses. Are the causative agents of rabies.
- Papoviruses. Cause papillomatosis in humans.
Retroviruses. They are the causative agents of HIV, and after AIDS.
Life-threatening viruses
Some viral diseases are quite rare, but they pose a serious danger to human life:
- Tularemia. The disease is caused by the Francisellatularensis bacillus. The clinical picture of the pathology resembles the plague. It enters the body by airborne droplets or by a mosquito bite. Transmitted from person to person.
- Cholera. The disease is fixed very rarely. Vibrio cholerae virus enters the body through the use of dirty water, contaminated food.
- Creutzfeldt-Jakob disease. In most cases, the patient has a lethal outcome. It is transmitted through contaminated animal meat. The causative agent is a prion, a special protein that destroys cells. Manifested by a mental disorder, severe irritation, dementia.
Determine what type of virus caused the disease, perhaps through laboratory tests. An important argument is the epidemic state of the region. It is also important to find out which virus is currently running.
Signs of viral infections and likelycomplications
The main part of viruses provokes the occurrence of acute respiratory diseases. The following manifestations of SARS are distinguished:
- development of rhinitis, cough with clear mucus;
- increase in temperature to 37.5 degrees or fever;
- feeling weak, headaches, loss of appetite, muscle pain.
Untimely treatment can cause serious complications:
- adenovirus can cause inflammation of the pancreas, leading to diabetes;
- beta-hemolytic streptococcus, which is the causative agent of tonsillitis and other types of inflammatory diseases, with reduced immunity can provoke diseases of the heart, joints, epidermis;
- influenza and SARS are often complicated by pneumonia in children, elderly patients, pregnant women.
Viral pathologies can also cause other serious complications - sinusitis, joint damage, heart pathology, chronic fatigue syndrome.
Diagnosis
Specialists define a viral infection by common symptoms, based on which virus is currently circulating. Virological studies are used to determine the type of virus. Modern medicine widely uses methods of immunodiagnostics, including immunoindication, serodiagnostics. Which tests to take for viruses are decided by a specialist based on a visual examination and anamnesis collected.
Assign:
- enzymatic immunoassay;
- radioisotope immunoassay;
- inhibition response studyhemagglutination;
- immunofluorescence reaction.
Treatment of viral diseases
The course of treatment is chosen depending on the pathogen, specifying which types of viruses caused the pathology.
For the treatment of viral diseases are used:
- Drugs that stimulate the immune system.
- Drugs that destroy a specific type of virus. A diagnosis of a viral infection is necessary because it is important to clarify which virus responds best to the selected drug, which allows for more targeted treatment.
- Medicines that increase the sensitivity of cells to interferon.
For the treatment of common viral diseases, use:
- "Aciclovir". It is prescribed for herpes, it eliminates the pathology completely.
- "Relezan", "Ingavirin", "Tamiflu". Prescribed for different types of flu.
- Interferons, together with Ribavirin, are used to treat hepatitis B. A new generation drug, Simeprevir, is used to treat hepatitis C.
Prevention
Preventive measures are selected depending on the type of virus.
Preventive measures are divided into two main areas:
- Specific. They are carried out with the aim of developing specific immunity in humans through vaccination.
- Non-specific. Actions should be aimed at strengthening the body's defense system, by providing small physical exertion, a properly composed diet and compliance with personalhygiene.
Viruses are living organisms that are almost impossible to avoid. To prevent serious viral pathologies, it is necessary to vaccinate according to the schedule, lead a he althy lifestyle, and organize a balanced diet.
