Viral diseases affect not only humans, but also fauna and flora. Viruses are capable of penetrating the organism of animals, insects, invertebrates, affecting plant cells and even bacteria. Specialists call viruses the most numerous biological form that is present in any ecosystem.
Viruses differ in structure, speed and path of transmission, mechanism of action on the host organism and other criteria. Some viruses pose a serious danger to humans, animals and plants due to their high pathogenicity. In some cases, viral infection causes irreversible damage to the population. In particular, the smallpox epidemic, which began after the arrival of Columbus, killed about 70% of the indigenous population of the Americas. At the same time, for Europeans this disease was less dangerous, since they had already formed immunity.
Treatment and preventive measures for viral diseases directly depend on the type of pathogen. According to this criterion, infections are divided into:
Among the most common respiratory infections are ARVI, influenza and parainfluenza, viral rhinitis, laryngotracheitis, pneumonia, bronchiolitis, and rhinopharyngitis. Coronavirus infection, avian influenza, SARS belong to the same group. The main mode of transmission of respiratory infections is airborne.
Gastrointestinal viral diseases are transmitted through dirty hands, raw water, unwashed fruit, and through the air. Rotaviruses, noroviruses, and adenoviruses fall into this category. They are capable of causing viral gastroenteritis, which is accompanied by inflammation of the mucosa of the stomach and intestines.
The vectors of exanthematous infections are mosquitoes. This category includes the molluscum contagiosum virus (group of smallpox, mainly children 1-10 years old are ill). These diseases affect the skin, causing a rash. Transmission is possible from a sick person to a healthy person by physical contact, through household items.
Neurological viral infections include encephalitis, which causes inflammation of the substance of the brain and/or spinal cord. Transmission of the virus occurs by insect bite. Mosquitoes and ticks are carriers of arbovirus, which, when ingested, leads to encephalitis. In addition to arbovirus, the cause of inflammation can be herpes simplex virus or rabies.
Among viral diseases of the liver, hepatitis is the best known. There are five types of hepatitis viruses. The disease is transmitted by contact with the blood and secretions of an infected person, some varieties of pathogens are able to be transmitted by fecal-oral route. In addition to hepatitis, disorders in the liver causes yellow fever virus, cytomegalovirus.
Herpesviruses and papillomaviruses cause diseases of the skin and mucous membranes. Transmission of infection occurs through physical contact. Some types of papillomaviruses are dangerous in that they can provoke the development of cancerous neoplasms.
Some groups of viruses cause hemorrhagic fever, which is accompanied by bleeding. Carriers of the disease are animals and insects.
Enteroviruses and cytomegaloviruses pose a special danger to people. Their transmission occurs by fecal-oral route. Enteroviruses can cause viral hepatitis, meningitis, myocarditis, affect the nervous and cardiovascular systems. Cytomegalovirus provokes the development of mononucleosis. In immunocompromised patients, this disease occurs with severe damage to the gastrointestinal organs and nervous system.