The parasite's life cycle: stages of development

Parasitism is called a form of relationship where one organism (the parasite) uses the other (the home) as a power source for temporary or permanent habitat. Master applied some of the harm, the parasite depends on its stage of development. The set of all stages is called a life cycle.

stages of parasites

Forms of parasitism

Forms of existence of the parasites varied. There are true, false form, as well as facultative and obligate parasitism. . Mainly engaged in the study of the phenomenon of true parasitism.

About parasites, when injected into a host organism of the carrier interferes with his life, but the cycle of their activity is short-lived. Examples about forms: leech in the nasopharynx and nasal cavity of an individual. This form can cause death of the carrier due to a blockage of the airway.

In the classification of the forms included:

  1. Obligate parasitism. Most of the group. All life cycles of the microorganism is associated with a person, he does not live outside the body or may not multiply. Examples: Rickettsia and chlamydia
  2. Optional parasitism. In this case, the microorganisms can lead a free life, but getting into the human body carry out a part of its development, which is included in the life cycle. Examples include species of synanthropic flies. Their larvae develop only in products, but once in the human gut, becoming the cause of intestinal myiasis.

Distinguish between parasitism at the time of contact. Temporary parasites use the host only as food. Example: blood-sucking arthropods.

Mature parasites are divided into the following types:

  1. Stationary. They carry out all stages of development inside the host or on it. It's the lice, the species Trichinella spiral, itch mites, and others.
  2. Periodic. Life cycle they spend or parasitic condition, or in free. An example is the eel intestinal.

How are cyclic stage

How is the life cycle of parasites? The functions of the following stages of development:

  • the function of the settlement;
  • stage of active growth.
  • standby function arriving in a foreign environment;
  • the function of asexual reproduction.
parasites

The host is called staging when live larvae of the parasite or they perform the function of asexual reproduction. In this case, it is a source of infection, permanent owners. Another value in the intermediate – cycle includes a stage of settlement. Sometimes the intermediate carrier provides the need for the development and survival because of the disappearance at the time of the final owners.

If the developmental cycle of the microorganism takes place with the change of two or three intermediate hosts, the first is called the intermediate 1, the second is optional.

In the end the owner is the cycle of development and reproduction sexually Mature stage of a microorganism. To the final host the parasite goes through an intermediate or by direct contact.

Reservoir parasitism can penetrate into the organism of the definitive host. In the reservoirs of the pathogen can survive for long, to build up and resettle in the surrounding areas.

Conqueror-the master allows to feed on ectoparasites. As they feed on parasites? They get there only to power. For example, bugs that feed on human blood. Another example is the mites.

The life cycle of parasitic microorganisms can be divided into two large groups:

  • Simple;
  • Complex.

In the simple group of cycles occur without change. Such organisms include Entamoeba histolytica, Ascaris, whipworm and others.

Difficult group includes several intermediates. It can be vertebrates, which are parasitic in their body goes through several stages of development, or reproduce. Examples: helminth eggs are transferred to food by flies or cockroaches.

Part parasitic organisms has a low specificity. They occur in wild animals, Pets, but can live in man. Such representatives are wolfarth fly, liver fluke, and a tapeworm. The cause of human infection in these examples become animals. Diseases caused by these pathogens are called zoonotic.

parasites in the body

How are parasitic organisms media? Pathogens which result in digestive tract, produce eggs or larvae in the faeces. Knowledge of the methods of breeding helps to identify the exact diagnosis of the pathogen.

If we compare the species that live freely and parasites, the life cycles of the latter is much more difficult. Free types easily cope with the problems of reproduction and resettlement, and parasitic organisms evolving from complex stages. They have a lot of larval cycles, present dwelling in various environments, various functions performed. These are the functions of settlement, rapid growth, passive waiting, reproduction.

30.09.2018