Obligate Parasites - What Are They, Symptoms And Treatment

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Obligate Parasites - What Are They, Symptoms And Treatment
Obligate Parasites - What Are They, Symptoms And Treatment

Video: Obligate Parasites - What Are They, Symptoms And Treatment

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Video: Microbiology lecture 6 | Obligate intracellular parasites | Rickettsia, Chlamydia bacteria 2023, February

What are obligate parasites, types and symptoms of infection


  • 1 Definition and characteristics of obligate microorganisms
  • 2 Morphology

    • 2.1 Reproductive system
    • 2.2 Nervous system
    • 2.3 Sense organs
  • 3 Features of the life cycle

    3.1 Stages

  • 4 Mechanism of infection
  • 5 Classification
  • 6 Common helminths
  • 7 Skin obligate parasitic organisms
  • 8 Intracellular parasites
  • 9 Treatment and prevention
  • 10 Conclusion

Human life can become significantly more difficult if his body is affected by parasites. Due to the fact that they use the host's nutrients, the patient suffers from a deficiency of vitamins and minerals. As a result, a person's immunity decreases and becomes vulnerable to various types of infections.

Among others, obligate parasites stand out in a special class, but they have the same methods of exposure and harmful properties as the rest, so it is important to fight them in a timely manner.

Definition and characteristics of obligate microorganisms


Obligate parasites are creatures that can only exist inside living organisms. At the same time, a certain type of parasitic creatures can live only inside a certain living organism, but outside of it it inevitably perishes.

This type of parasite includes ticks, lice, helminths, intracellular microorganisms.

Parasitic organisms suppress the host's immune system, limit the supply of nutrients and essential food components, and cause intoxication and destruction. Most of them are among the simplest, leading anaerobic way of existence and habitat.

At the same time, parasites are able to multiply rapidly (each female can give birth to more than a million units of offspring), which accelerates the process of oppression of the host's organism.


In the course of evolution, the morphology of obligate parasites is constantly changing. Thus, their ability to adapt is improved and survival is increased.

Reproductive system

The reproductive system of organisms is very developed. Due to this, females can lay more than a million eggs per day, from which viable larvae are obtained, which are highly resistant to external environmental influences. This is especially true for helminths.


Nervous system

The nervous system of organisms is primitive due to the stability of their habitual habitat. In such an environment (in the host's body), a mandatory response to changes in humidity and temperature, light or smell is not required.

The basis of the entire parasite system is the periopharyngeal nodes.

Sense organs

In this case, this system is of relatively little importance. Therefore, the organs for the most part are reduced, underdeveloped and practically devoid of sensitivity.

Life cycle features

All types of parasitic creatures have two types of life cycle: simple and complex. Obligates have a simple cycle, since they do not need an intermediary host.



The life cycle of creatures can take place in two main stages:

  1. Peace. The creature settles in the host's body on a permanent basis, has the provision of everything necessary for normal life. Does not need relocation.
  2. Activity. In this case, the eggs are in the environment for waiting for settlement in the body of the new host.

In the human body, parasites live in the form of mature, developed creatures, which are inherent in unlimited reproduction. Thus, not only the constant existence of parasitic organisms occurs, but also their gradual accumulation.

Infection mechanism

As a rule, parasites enter the host organism through intermediaries in the form of larvae. This is possible in the following ways:

  • Through an insect bite;

  • Contact with animal carriers and wild animals;
  • Through drinking and food;
  • Inherited from mother to child;
  • Through close contact, including sex.

Once in the human body, obligate parasites accumulate in the areas of the body most suitable for existence through the lymphatic system or blood. As soon as they develop into adults, they begin to reproduce.

In order to move to the body of a new host, the larvae are often excreted along with the feces. The exceptions are lice and ticks - they multiply right on the surface of the human body.


According to statistics, people most often suffer from helminthiases. According to the methods of infection, they are divided into the following groups:

  1. Biohelminths. They settle in the human body through contact with animals and cause echinococcosis, trichinosis, opisthorchiasis, teniasis. Pathologies are diagnosed quite often to varying degrees.
  2. Geohelminthiasis. Typically, the infection occurs through the soil and fruits. Thus, ascariasis, noncatorosis, trichocephalosis occurs. The likelihood of contamination increases when the soil is treated with manure.
  3. Enterobiasis. It is transmitted through direct contact with sick people.



Obligate parasites are classified according to their location in the human body. So, the following varieties are distinguished:

  • Endoparasites (localized inside the body);
  • Ectoparasites (live on the skin);
  • Intracellular parasites (can only exist inside the host cell).

Intracellular organisms are considered the most dangerous. However, in large quantities, all of the listed species pose a serious danger to human health and life.

Common helminths

Helminthiasis is common in children, but can also be found in adults. In this case, the presence of the following types of parasites is more often diagnosed:

  1. Pinworms. This type of worm is classified as a type of flatworm that lives in the human intestine. They lay eggs in the colon and secrete toxic substances that cause itching. This phenomenon is often defined as a symptom of the progression of helminthiasis. In addition, patients may experience indigestion, impaired stool, systematic nausea, and decreased performance.
  2. Pork tapeworm. Transmitted through contaminated foods that have not been properly cooked. This type of worm also exists in the human gastrointestinal tract and causes a decrease in the host's resistance to disease, as well as intoxication, general malaise and indigestion.
  3. Ascaris. These parasites pose the greatest danger to humans, especially in childhood. Worms negatively affect the functioning of the nervous and respiratory systems of the body, cause the progression of anemia and vitamin deficiency.

Skin obligate parasitic organisms

Skin parasites are less dangerous to human health and life, but they can also cause serious discomfort. Among the most common ones are:

  1. Lice. Organisms feed on human blood and inhabit areas of the skin covered with hair, most often on the head. Infection usually occurs through contact with sick people. As a result of the activity of lice, itchy skin occurs, seborrhea and dandruff appear, and hair loss.
  2. Scabies mite. It dwells and feeds on useful human components directly under the upper layers of the skin, gnawing through passages that cause severe itching. As a result of the vital activity of the tick, scabies is formed, among the symptoms of which are blisters, redness and swelling on the skin, discomfort and irritability. In addition, the itch mite can become a carrier of infections dangerous to humans.
  3. Demodex. This type of mite causes demodicosis of the eyes, characterized by constant accumulations of yellowish fluid and crusts on the eyelashes and around the visual apparatus. The disease is transmitted through direct contact with an infected patient, as well as through the use of general hygiene products.


Intracellular parasites

Obligate intracellular parasites not only bring serious discomfort, but also pose a great danger to humans. This is due to the fact that settling in the host's body, they cause serious diseases and abnormalities. The most common of microorganisms:

  1. Chlamydia. These parasites cause chlamydia and are sexually transmitted. Treatment of pathology should be timely and simultaneous for both partners.
  2. Viruses. They form dangerous diseases that require timely therapy and isolation. Currently, viruses are not well understood, therefore, the treatment and prevention of not all diseases that they cause are highly effective. They can be transmitted through direct contact, through contaminated blood transfusion, and through sexual contact.
  3. Rickettsia. Cause spotted fever and typhus. Can be transmitted through the bite of wild rodent vectors or through ingestion of contaminated raw chicken eggs.


Treatment and prevention

The method for diagnosing the problem is selected depending on the type of disease. So, to identify helminths, anamnesis, ultrasound examination, and fecal analyzes are performed. Detection of skin parasites is possible with the help of external examination and examination of scrapings, intracellular ones are detected using smears.

Only after the diagnosis is established, treatment is prescribed.

It is impossible to completely protect yourself from infection. However, in order to minimize the likelihood of the occurrence of the corresponding diseases, it is necessary to use the following rules and recommendations:

  • Observe basic hygiene rules;
  • Avoid contact with wild animals and rodents;
  • Provide protection from insects;
  • Thoroughly wash vegetables and fruits before eating;
  • Wash hands with soap and water after working on the ground and contact with pets;
  • Use personal protective equipment and contraception.

    Wash your hands with soap
    Wash your hands with soap
    Avoid contact with wild animals and rodents
    Avoid contact with wild animals and rodents
    Wash vegetables and fruits thoroughly
    Wash vegetables and fruits thoroughly


Obligate parasitism is a very harmful and dangerous phenomenon for human health, which can lead to the depletion of vital resources

In addition, parasitic organisms cause discomfort and impair the host's quality of life. That is why it is important to prevent infection and timely diagnose the possible presence of a lesion.

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