Parasitology is a complex biological science that studies the phenomena of parasitism as a type of relationship between organisms. The word "parasite" is Greek and literally means one who feeds at the expense of another or others (para, about; sitos, food). Parasitism is a universal phenomenon of nature, the most common form of symbiosis. Parasites are all viruses, many bacteria, some fungi and higher plants. In the animal kingdom, parasites include 55,000 species of protozoa, 7 000 species of arthropods, 20,000 species of worms. Some classes are completely parasitic organisms are completely represented. These are sporozoans, suckers, and tapeworms. Only the Sponges and Cephalopods are parasitic. and the intestine-swimmers. The main subject of study in parasitology is The relationship between the parasite and the host, their mutual influences and dependence on environmental factors. The object of parasitology is a complex
read moreThe object of parasitology is a complex system of relationships between units of the "parasite-host-environment" system. environment", the parasite is studied to a greater extent. The tasks of parasitology are: a) the study of the structure of the parasite, b) peculiarities of its vital activity, c) adaptations to dwelling in the host organism, d) characteristics of life cycles and geographic distribution, e) the influence of the parasite on the host and the conditions under which this influence conditions under which this influence is manifested. The interdisciplinary relationship of parasitology: Zoology, botany, microbiology, virology, pathological anatomy, pathological physiology, biochemistry, immunology, etc. Sections of parasitology: General parasitology (studies general patterns of parasitism), Medical parasitology (studies human parasites), Veterinary parasitology (studies parasites of domestic and farm animals)
read moreThe widespread and diverse forms of parasitism make it difficult to unambiguous definition of this concept. Currently, there are more than 50 different formulations of the concepts of "parasite" and "parasitism". All of these definitions can be summarized in several basic concepts parasitism, which differ, first of all, by the choice of the main criterion laid down in the basis of the definition. 1) The ecological concept. Proponents of this concept recognize parasitism as the main criterion of parasitism recognize the dwelling of one organism in another (Pavlovsky, 1934; Filipchenko, 1937; Dogel, 1951; Oshmarin, 1988, etc.). According to the characterization of A.A. Filipchenko (1937), parasites are organisms "... whose habitat is other living organisms ...". However, some other forms of symbiotic interactions (commensalism, mutualism), where the habitat habitat of one partner is an organism of another animal or plant.
it is known that only a few parasites pass completely life cycle in the host. The vast majority of them, in their various stages of development, live in the external environment. at various stages of development live in the external environment, and in some cases for for a sufficiently long time (bacteria, viruses, some nematodes). 2) The metabolic concept considers parasitism as a form of relationship in which the metabolism of one organism is of one organism is dependent on that of another organism (Vavilov, 1987; Soprunov, 1987; Smith, 1969; Noble, 1976, etc.). This is the main difference parasitism from such forms of relationships as quartierism and commensalism, which are characterized by weak metabolic relationships of partners or their absence. At the same time, many parasites, particularly Particularly helminths are capable of utilizing alternative pathways to maintain their own metabolism. 3) Pathophysiological concept. The main criterion of parasitism is the harm (harmfulness) caused by the parasite to the host (Kholodkovsky, 1914; Schultz, 1970; Dyakov, 1973; Lebedev, 1989; Logachev, 1990, etc.). At the same time, this concept recognizes that the host is also not indifferent to the introduction of a parasite into it, and is capable of have a depressing or lethal effect on the latter. In addition supporters of the concept do not always distinguish the role of pathogenic action of parasites at the population level (where it can be considered progressive) and organism level. 4) Immunological concept. The concept is based on the ability host to recognize the parasite as a foreign substance and form protective reactions (Sprent, 1963; Schultz, 1967; Britov, 1991). In doing so Parasites are equated with other immunogenic factors (e.g, grafts, tumors). However, such a similarity has, probably, convergent nature.
