Viruses are non-cellular organisms, representing a minimal form of life. Their components serve as those necessary elements that enable the parasitic existence and further reproduction. The size of the viruses is very small. They range from several tens to thousands of nanometers.
Viruses are classified as cellular parasites. Their main feature is the ability to reproduce and exist only in certain conditions. They can draw the necessary resources for functioning only from the host cell, which is considered to be a cell infected with a virus. Being in the environment outside the body, the particles of parasites have the ability only to save and transfer the genetic information embedded in them. The form of the extracellular virus is called the virion.
Parasitic particles can exist in all living organisms. Human viruses can cause a large number of ailments, which are extremely dangerous for its existence. Among these diseases can be called bird flu and AIDS, natural (black) smallpox and atypical form of pneumonia. These common ailments include massive colds that are common for us, as well as flu and rubella. Some animal viruses that can infect the human body are also known. This ability appears in them under certain conditions. An example of this is the bird flu virus H5N1 .
In nature, there are a huge number of parasitic forms of the existence of life. For greater convenience of their study, various types of classification systems have been developed. The most widely used is the combination of two of them: ICTV and Baltimore.
The viral structure is a strand from a nucleotide chain. These substances are the main elements in the composition of nucleic acids.
Human viruses, the types of which are distinguished by their structure, can be:
- neurotropic (various viral encephalitis and rabies);
- dermatropic (smallpox and foot and mouth disease);
- pneumotropic (flu);
- viscerotropic (pork plague).
Various pathogens are also included in the virus category, which belong to the transition group from the minimum form to bacteria. This group includes rickettsia. These are rod-shaped, spherical or club-shaped microorganisms, similar in structure to bacteria, and in the method of reproduction with viruses, since their vital activity is possible only inside host cells. Rickettsia cause Marseille fever, as well as flea or rat typhus.
The human viruses included in the following group are chlamydia or pararicetxia. These pathogens in their structure are close to bacteria and therefore it is possible to get rid of them by using antibiotics.
The most famous diseases that occur due to the fault of viruses are SARS. Now more than three hundred subtypes are known that belong to the five groups of the parasitic form that provoke the occurrence of this disease. These include human viruses that provoke the occurrence of influenza and parainfluenza. As well as rheo- and renoparasitic forms.
Human viruses that cause a benign tumor are classified as papillomaviruses. They provoke the growth of neoplasms, similar in appearance to warts. Papillomas occur both on the skin and on the mucous membranes of the oral cavity, pharynx, and sinuses. Benign tumors can appear on the vocal cords and even in the bladder. The treatment of human papillomas requires prior consultation with a specialist. When a neoplasm appears, it is urgent to contact a dermatologist. The cause of papillomas is a violation of the health of the body. In general, gastritis and kidney disease, advanced colitis, as well as gynecological and some other ailments contribute to the occurrence of neoplasms.