“PEDAGOGS”
international research journal ISSN:
2181-3027
_SJIF:
5.449
https://scientific-jl.com/ped
Volume-84, Issue-1, June -2025
30
UDК 576.89
ЕPIDEMIOLOGICAL FEATURES OF PARASITIC DISEASES
Fakhriddinova Sh.F.
faxriddinova.shaxnoza@bsmi.uz
Bukhara State Medical Institute
Summary.
Helminthiasis constitutes the largest group of parasitic diseases. They
are caused by parasitic worms or helminths. More than 250 species of helminths have
been registered in humans. Of this number, about 30 are common human parasites and
form foci with significant infestation, and the rest are animal helminths that infect
humans more or less accidentally.
Keywords:
helmints, epidemiologi parazits.
Various forms of parasitism. Parasitism is not an independent condition, completely
separate from some conditions of the animal world. It comes in several forms. The main
problems associated with parasitism are symbiosis and synocysion.
During these events we look at the interaction of two different animal species. All
living organisms on Earth are divided into two groups based on nutrition: 1. Autotrophic
organisms. 2. Heterotrophic organisms
Autotrophic organisms synthesize organic substances from inorganic substances.
These include green plants.
Heterotrophic organisms are those that feed on ready-made organic matter. In turn,
they can be divided into herbivores, omnivores, etc. Carnivorous animals, in turn, are
divided into parasites, predators and saprophytes. Parasites are divided into parasites of
humans, animals and plants. All living organisms interact directly and indirectly with each
other.
In the process of evolutionary development, this connection between organisms
becomes more or less complicated and is biologically divided into different categories,
that is, animals form different groups and live together in neutral (indifferent), friendly
and antagonistic relationships.
Indifferent-neutral relationships. They live in the same conditions, in the same
environment (territory), and do not harm or bring any benefit to each other. Examples of
this are coral polyps, igneous starfish and crinoids.
II.
Antagonistic – opposite relationships. In such a situation, one of the
cohabitants causes harm to the other. Examples of this are predation and parasitism.
III.
Symbiosis is a mutually beneficial relationship. The meaning of symbiosis is
“sim” - together, “bios” - life (living), both living together benefit from each other to one
degree or another.
“PEDAGOGS”
international research journal ISSN:
2181-3027
_SJIF:
5.449
https://scientific-jl.com/ped
Volume-84, Issue-1, June -2025
31
Symbiosis is very complex and takes several forms. Even one cannot live without
the other. Initially, such coexistence becomes necessary only for one of the cohabitants,
since he cannot independently communicate with the external environment.
Symbiosis is a very complex relationship between two organisms belonging to
different species. M: Hypermastigins live in the intestines of termites.
When termites were
cleared of parasites in the laboratory, the parasites died immediately. When termites with
parasites and termites without parasites were observed under the same conditions, termites
with parasites lived up to 1.5 years given sufficient food and favorable conditions, while
termites without parasites lived only 10-14 days and then began to die.
Another form of symbiosis is synoikia (syn-together, oikos-house, place). This is
such a coexistence that both animals living together can be neutral towards each other, or
one of them uses the other, but does not harm him in any way. Thus, one of the cohabitants
slowly serves the other and does not see any benefit for himself from such cohabitation.
Sometimes one of the cohabitants, due to his small size or very slow mobility, climbs
onto the div of the other cohabitant and lives with him as a companion. Such
relationships can be expressed by the general term “lease”. There are several types of
rental housing.
Simple rent - lives in the div of the owner or within the limits of his influence.
When living together in a rented apartment, one organism uses the other as a home. For
example, the mustard fish protects its eggs from enemies by placing the eggs in the mantle
of toothless bivalves, or the very small Fierasphere fish hides under the umbrellas of
jellyfish in case of any danger.
2. Epioikia - a tenant living on rent sits on his div and uses it as a means of
transportation. M: Crustaceans belonging to the genus Cirripeda cling to the bodies of
whales and sharks and use them as transport, while they themselves feed on plankton, or
sticky fish passively cling to the shark with their dorsal fin and feed on food left by the
sharks. . In this case, the sticky fish spreads to other places at the expense of sharks, which
is called epioikia.
3. Entoikia - along with sitting on the owner, it is used for feeding at his expense. M:
Fishes of the ammotid family live in the watery lungs of sea cucumbers, but can sometimes
go out into the water and feed on small crustaceans.
One of the main manifestations of synoikia is commensalism. In a commensal
relationship, one organism does not harm another organism by eating unwanted food.
Forms of communication between parasites and hosts. Facultative parasitism is a
phenomenon in which some free-living organisms enter other organisms and survive.
Facultative parasitism is important in studying the origin of parasites.
When free-living organisms become parasitic, their structure and physiology must
have specific characteristics and certain conditions. M: Owners must have strong skin, not
exposed to digestive juices, and be able to live in anaerobic conditions.
“PEDAGOGS”
international research journal ISSN:
2181-3027
_SJIF:
5.449
https://scientific-jl.com/ped
Volume-84, Issue-1, June -2025
32
In rare cases, false parasitism also occurs. In this case, some organisms accidentally
end up in the div of a second organism that has not adapted during evolutionary
development. But this organism cannot live in the div (for example, an earthworm can
come out of the intestines of vertebrates). If the larvae or eggs of various flies and
mosquitoes enter the human div through food, they cause various symptoms of illness
(diarrhea, nausea, vomiting and nausea).
Parasites are divided into temporary and stationary (permanent) depending on the
duration of their stay in the host’s div.
In temporary parasitism, the parasite temporarily
lives in the host’s div, feeds normally, but does not develop or reproduce. In this case,
there are no harmonic connections between the parasite and the host. The parasite enters
the host's div only during feeding.
These include many blood-sucking ectoparasites (mosquitoes, flies, ticks, bedbugs,
leeches, etc.). Stationary parasitism is studied in two ways. Periodic and permanent. In
periodic parasitism, parasitism occurs during the developmental cycles of organisms.
Some organisms parasitize during the larval period (larval parasitism, m: mermitidae).
Some of them parasitize in the adult period (imaginally) (m. nematodes - Strongilidae).
Helminths are parasitic multicellular organisms belonging to the lower worms of
the Scolecida type.
Epidemiological features of helminth infections are determined by the biological
characteristics of helminths.
Non-contagiousness of helminthiasis. An infected person is generally not
contagious to others (with the exception of enterobiasis, hymenolipediasis; sometimes
- taeniasis, strongyloidiasis).
The disease is transmitted mainly through contaminated hands, unboiled water,
household items, and eating unwashed fruit. You can become infected anywhere if you
fail to follow basic rules of personal hygiene or careless attitude to nutrition.
Symptoms
of helminthic infestation are not always noticeable; for a long time, the disease can
masquerade as other problems. Detection of parasites during a medical examination or
targeted examination for suspected helminthiasis is a reason for treatment. The disease
is more common in children of preschool and school age and is manifested by the
following symptoms:
in children it begins with a decrease in appetite, nausea,
abdominal pain, the child becomes capricious, whiny, due to a disorder of the nervous
system, children stop growing mentally and physically; and sometimes convulsions
may also occur. In adults, allergic rashes, itchy skin, and allergic diseases are more
common.
The human div is an ideal habitat for parasites; they can live for years not only
in the intestines, but also in other organs (lung tissue, liver parenchyma, eyeballs, skin,
circulatory system, myocardium, brain), causing serious harm to health. The size of
these “illegals” varies from microscopic (protozoa) to tens of meters (tapeworms).
“PEDAGOGS”
international research journal ISSN:
2181-3027
_SJIF:
5.449
https://scientific-jl.com/ped
Volume-84, Issue-1, June -2025
33
Taking into account mutual fitness, helminths and hosts are divided into two
groups: obligate and facultative helminths and, accordingly, obligate and facultative
hosts. An obligate helminth is one whose evolution is closely related to the evolution
of the host. Such a helminth has optimally adapted to the conditions of the biochemical
and biophysical environment present in the organs and tissues of a given host.
Outside
the div of a given host, the parasite would not be able to withstand competition in the
struggle for existence. The obligate host of this helminth is characterized by the fact
that it is in it that the parasite is ensured the greatest survival rate, the fastest and most
complete growth. An example of obligate parasites and hosts is humans and
roundworms.
Facultative parasites are those whose evolution occurred independently of the
evolution of the given host, therefore they are poorly adapted to the conditions of the
biochemical and biophysical environment present in the organs and tissues of the host.
Under these conditions, the facultative parasite has extremely low viability.
A
facultative parasite is found infrequently in the div of a facultative host and in most
cases in a small number of copies. Examples of facultative hosts and parasites include
humans and trichostrongylids.
The localization of helminths is very diverse. Helminths can parasitize almost all
human organs and tissues. The most common site of localization is the gastrointestinal
tract. The lungs are the site of localization of the parasite during paragonimiasis and
the site of temporary localization of the larvae of migrating nematodes (ascariasis,
toxacariasis, hookworm disease, etc.).
Echinococcus can sometimes be localized in the
lungs. Helminths can parasitize in the blood (schistosomiasis, filariasis). The larvae of
migratory nematodes, as well as a number of helminths that parasitize humans in the
larval stage in various tissues (echinococcus, cysticercus, trichinella, etc.), can
temporarily be present in the blood and spread hematogenously. Some helminths
(echinococcus, cysticercus) can parasitize the central nervous system.
When the
digestive organs are damaged, helminths are characterized by strictly defined
localization. In particular, bovine and pork tapeworms, wide tapeworms and
roundworms (in the mature stage) are fixed in the upper part of the small intestine,
dwarf tapeworm - in the lower third of it, whipworm - in the large intestine,
opisthorchis - in the bile ducts of the liver and pancreatic ducts.
Some helminths can
be localized in various organs. Thus, cysticercus can parasitize the brain, eyes,
intermuscular connective tissue and subcutaneous tissue, heart, and liver.
Echinococcus most often affects the liver and lungs, but can also parasitize the central
nervous system, genitals, kidneys, muscles, eyes, and sometimes other organs and
tissues.
There are intensive and multiple invasions. The intensity of invasion is
determined by the number of parasitic helminths of one species. It can range from one
“PEDAGOGS”
international research journal ISSN:
2181-3027
_SJIF:
5.449
https://scientific-jl.com/ped
Volume-84, Issue-1, June -2025
34
to several thousand copies (ascariasis, enterobiasis, trichuriasis), even with invasion by
large helminths (wide tapeworm, etc.), the number of parasites can reach 10 or more.
Multiple infestations refer to the parasitism of several types of helminths. There
may be 2-3 or even 4 types of helminths. Simultaneous parasitism of more than five
species of helminths is very rare.
LITERATURE:
List of basic literature:
1. П. Мамчик
,
О.В. Каменева, И.В. Колнет, Н.В. Габбасова, О.А.
Панина, С.Е.Савельева Учебное пособие по эпидемиологии для
студентов лечебного факультета2//2007
2. Эпидемиология: Учебник. / Л.П. Зуева, Р.Х. Яфаев. - СПб : ООО «ФО-
ЛИАНТ», 2006. - 752 с.
3. Инфекционные болезни и эпидемиология / В.И. Покровский и [др.]. - М. :
ГЭОТАР-МЕД, 2003. -816 с.
4. Эпидемиология: учебное пособие./ Ющук Н.Д., Мартынов Ю.В. - М.:
Медицина, 2003. - 448 с.
5. Шапошников А.А., Карниз А.Ф. Организация санитарно-гигиенических и
противоэпидемических мероприятий а чрезвычайных ситуациях на со-
временном этапе/А.А. Шапошников, А.Ф. Карниз - М.: Медицина, 2001.--304
с.
Список дополнительной литературы:
6. Б.А.Ревич, С.Л.Авалиани. Г.И.Тихонова Экологическая эпидемиология.
Учебник - М: Издательский центр «Академия», 2004. - 53-86.
