Viruses are non-cellular infectious agents with a genome (DNA and RNA), but not gifted with a synthesizing apparatus. To reproduce these microorganisms, cells of more highly organized organisms are needed. Once in the cells, they begin to multiply, causing the development of various diseases. Each virus has a specific mechanism of action on its carrier. Sometimes a person does not even suspect that he is a virus carrier, since the virus does not harm health, this condition is known as latency, such as herpes.
To prevent viral diseases, it is important to maintain a healthy lifestyle, strengthening the body's defenses.
Origin and structure
There are several hypotheses about the origin of viruses. Science offers a version about the emergence of viruses from fragments of RNA and DNA that are released from a large organism.
The regression hypothesis states that viruses are parasitic organisms with small cells that multiply in larger species, but during the evolutionary period they lost the genes required for the parasitic form of survival.
Co-evolution suggests that viruses appeared simultaneously with living cells as a result of building complex sets of nucleic acids and proteins.
Questions about the structure of the virus, how it propagates 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), which acts as a defense.
Viruses come in many forms, they are distinguished from a simple spiral form to an icosahedral one. The standard value is approximately 1/100 of the size of the average bacterium. However, most viruses are very small, which makes it difficult to study them under a microscope.
Is matter living a virus?
Two definitions of life forms of viruses are distinguished. According to the first, extracellular agents are a combination of organic molecules. The second definition states that viruses are a special form of life. It is impossible and concrete to answer the question what viruses exist, since biology assumes the constant appearance of new species. They are similar to living cells in that they possess a special set of genes and evolve according to the natural set method. They need a host cell to exist. The lack of their own metabolism does not allow them to reproduce without assistance.
Modern science has developed a version according to which certain 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 a weakened immune system and an increase in temperature, when a favorable condition is formed so that human viral diseases get further development 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 multiply actively, parasitizing in different areas of the body, using them as a nutrient substrate. Viruses, as a result of their life activity, cause cell death, which precedes the manifestation of the clinical symptoms of the disease.
Plant viruses
If you wonder what viruses are, then, in addition to viruses that are dangerous to the human body, you can select a special type of viruses that infect plants. They are not dangerous to humans or animals, since they can only reproduce in plant cells.
The plant world can be protected from pathogenic microorganisms using the resistance gene. Often, virus-infected plants begin to synthesize substances that destroy parasitic agents (NO, salicylic acid). The danger of these viruses is that they affect yield.
Artificial viruses
Artificial viruses are created to obtain vaccines against infections. The list of what viruses are in the arsenal of medicine created by artificial means is not completely known. However, it is safe to say that the creation of an artificial virus can have a lot of consequences.
Such a virus is obtained by introducing an artificial gene into the cell that carries the information necessary for the formation of new types.
Viruses affecting the human body
What viruses are on the list of extracellular agents that are dangerous to humans and cause irreversible changes? This is an aspect of the study of modern science.
The simplest viral disease is a cold. But against the background of a weakened immune system, viruses can cause quite serious pathologies. Each pathogenic microorganism affects the organism of its host in a certain way. Some viruses can live in the human body for years and not cause harm (latency).
Certain latent species are even beneficial to humans, as their presence forms an immune response against bacterial pathogenic agents. Some infections are chronic or lifelong, which is purely individual and is due to the protective ability of the virus carrier.
Virus spread
The transmission of viral infections in humans is possible from person to person or from mother to baby. The transmission rate or epidemiological state depends on the population density of a given region, weather conditions and season, as well as on the quality of medicine. It is possible to prevent the spread of viral pathologies if it is timely to clarify which virus is currently being detected in most patients and carry out appropriate preventive measures.
Kinds
Viral diseases manifest themselves in completely different ways, which is associated with the type of extracellular agent that caused the disease, with the location, with the rate of development of the pathology. Human viruses are classified as deadly and sluggish. The latter are dangerous in that the symptoms are unexpressed or weak, and it is not possible to quickly find 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 specify which viruses are and which pathogens cause diseases that are dangerous to health:
- Orthomyxoviruses. This includes all types of influenza viruses. To find out which influenza virus caused the pathological condition, special tests will help.
- Adenoviruses and rhinoviruses. Affect the respiratory system, cause SARS. The signs of the disease are similar to the flu, they can cause such serious complications as pneumonia, bronchitis.
- Herpes viruses. They are activated against a background of reduced immunity.
- Meningitis. Pathology is caused by meningococci. The mucous membrane of the brain is affected; cerebrospinal fluid is a nutrient substrate for the pathogenic organism.
- 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 cramps, inflammation of the spinal cord, paralysis.
- Picornaviruses. Cause hepatitis.
- Orthomyxoviruses. Provoke mumps, measles, parainfluenza.
- Rotavirus. An extracellular agent causes enteritis, intestinal flu, gastroenteritis.
- Rhabdoviruses. They are the causative agents of rabies.
- Papoviruses. Cause human papillomatosis.
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. Francisellatularensis infectious bacillus disease is caused. The clinical picture of the pathology resembles the plague. It penetrates the body by airborne droplets or by a mosquito bite. Transmitted from person to person.
- Cholera. The disease is recorded very rarely. The Vibrio cholera virus enters the body through the use of dirty water and contaminated food.
- Creutzfeldt-Jakob disease. In most cases, the patient has a fatal outcome. Transmitted through infected animal meat. The causative agent is prion - a special protein that destroys cells. It manifests itself as a mental disorder, severe irritation, dementia.
Determining what type of virus caused the disease is possible through laboratory tests. An important argument is the epidemic state of the region. Finding out which virus is currently walking is also of considerable importance.
Signs of viral infections and possible complications
The bulk of viruses provokes the occurrence of acute respiratory infections. The following manifestations of ARVI are distinguished:
- development of rhinitis, cough with clear mucus;
- increase in temperature to 37.5 degrees or fever;
- feeling of weakness, headaches, loss of appetite, muscle pain.
Untimely treatment can cause serious complications:
- adenovirus can cause inflammation of the pancreas, which leads to the development of diabetes mellitus;
- 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;
- flu and acute respiratory viral infections are often complicated by pneumonia in children, the elderly, pregnant women.
Viral pathologies can cause other serious complications - sinusitis, joint damage, heart pathology, chronic fatigue syndrome.
Diagnostics
Experts determine a viral infection by its common symptoms, based on which virus is currently walking. Virological studies are used to determine the type of virus. Modern medicine widely uses methods of immunodiagnostics, including immuno-indications, serodiagnostics. Which tests to take for viruses, the specialist decides on the basis of a visual examination and a collected history.
Assign:
- enzyme immunoassay;
- radioisotope immune analysis;
- investigation of hemagglutination inhibition response;
- immunofluorescence reaction.
Viral disease treatment
The course of treatment is selected depending on the pathogen, specifying which types of viruses caused the pathology.
For the treatment of viral diseases, apply:
- Immune stimulating drugs.
- Medicines that destroy a specific type of virus. A diagnosis of a viral infection is necessary, since it is important to clarify which virus responds better to the chosen drug, which makes therapeutic therapy more targeted.
- Medications that increase the sensitivity of cells to interferon.
For the treatment of common viral diseases, apply:
- "Acyclovir." Appointed with herpes, it eliminates the pathology completely.
- “Relesan”, “Ingavirin”, “Tamiflu”. Assign for different types of flu.
- Interferons along with Ribavirin are used to treat hepatitis B. A new generation of drugs, 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 in order to develop a specific immunity in a person by vaccination.
- Nonspecific. Actions should be aimed at strengthening the protective system of the body, by providing small physical exertion, a properly composed diet and compliance with personal hygiene.
Viruses are living organisms that are almost impossible to avoid. To prevent serious viral pathologies, it is necessary to vaccinate according to the schedule, maintain a healthy lifestyle, and organize a balanced diet.