Invertebrates        18 ноября 2018        607         0

Metacercaria worm parasite. Description, features and nutrition of metacercaria

Modern medicine fixes many parasitic diseases, pathogens that penetrate into human organs. One of the reasons for the formation of pathologies is the use of poorly cooked fish .


The second reason is relevant if cooking fish does not comply with the correct technology. Lovers of raw fish become frequent patients with the conclusion of parasitic diseases.

A heavy helminth among trematodoses is metacercarium . It is located inside the fish , crabs, is directly related to the group of flatworms. Helminths of this species penetrate all the insides of the fish .

The most dangerous are the penetration into the eyes and brain of fish . Also, worms tend to settle in aquariums. They get there from reservoirs, move together with snails. Not rarely get with food in a comfortable home of fish and actively attack live, healthy organisms.

Features and habitat of metacercaria

Metatsercariae of opisthorchis are located in the muscle tissue of the carp detachment. For the cecarius (larvae), the fish is the intermediate host. In it, cecaria develop into metacercariums. Parasites do not have the property of being passed from one fish to another, being larvae.

Infected with helminth can only be formed adult parasites. Scientists have proven that the lake carp, minnow, river barbel, syrt under no circumstances can not be infected.

Worms in most cases are located in the eyes, striking at the same time:

  • eye lenses;
  • vitreous body;
  • internal environment of the eyeballs.
    There are four groups that combine thirteen forms of damage to the eye and lens. Metatascarii are dangerous because they are sustainable in their environment. They are not afraid of low temperatures.

Metacercariae in fish

Only by freezing the product to -40 ° C for at least 7 hours the larvae disappear. If the freezing takes place at — 35 ° C, cecaria lose their viability after 14 hours of cold.

If you freeze fish at — 28 ° C, it takes at least 32 hours to get rid of the parasite. But to high degrees, parasites are sensitive faster. After the procedure of excretion from fish, they die in 5–10 minutes at + 55 ° C.

Developing trematode metacercaries, have features:

  • alternate generations;
  • change owners.
    Mollusks, fish, and insects act as intermediate hosts for trematodes. Still this type of worms has an additional host. But in 80% of cases it can do without it during development.

The generations alternate with the reproduction of parasites not only in the formed worms, but also in the larvae. The larvae give birth to another generation of cecarius, which as a result develop into an adult form.

Character and lifestyle of metacercaria

Metacercaria differ from other helminths in their class by their small size. The body of the helminth is equipped with two suckers:

1. abdominal;
2. oral.

Worms attack the mucous membranes of their host, sucking the nutrients, thereby supporting their livelihoods. The oral sucker is the beginning of the digestive tract. The rear end of the calf has a channel to excrete processed food.

Getting into the gills of fish , the worms do not multiply. Living in this environment, they have no opportunity to eat and grow. They are waiting for the moment when the host fish will be eaten. During this entire period, microorganisms hide inside the capsule, which is formed by the cartilage tissue of the fish .

Metarcercaria tend to release toxic substances, leading to gill lobes to death. Fish weaken, are on the surface of the water, because they experience an insufficient amount of oxygen.

The fish falls into the net of fishermen, or it becomes a victim of birds , dogs , cats. After eating sick fish, helminths attack the organism of the final host, which often leads to the development of a pathology called clonorchis metacercaria .

Parasites have a negative effect on the host fish . It becomes restless, is affected by bacterial infections, which leads to the process of fin rot. According to statistics, mortality of ornamental fish affected by metarcercaria is 50% or more.

Metacercaria Nutrition

Metarcercaria live inside vertebrates, attached firmly with suckers, having intestines. Microorganisms feed on the tissues of their host or the contents of its intestines. If worms get into the gills of fish, they don’t eat at all. Their function is to infect a fish with an infection for destruction by its final owner.

Reproduction and longevity of metacercaria

There is a long period of time inside the live fish metacercaria of opisthorchiasis . Their average viability is from 5 to 8 years. Penetrating into the organism of the final host, full maturation is characteristic of parasites, at which the worm becomes from 0.2 to 1.3 centimeter long, up to 0.4 centimeters wide.

If the owner is a human being, the worms live in his gallbladder, pancreatic ducts, bile ducts of the liver. Fully formed, metacercariae lay their eggs, which are released into the environment along with the secreted feces.


Further, the parasite develops in stages, penetrating into the intermediate host clam. After getting into the carp fish, an additional host of worms. The mature parasite has an oval or round cyst, inside of which the larva remains.

With the late detection of metacercariae, and improper disposal of it in the body of the final owner, a number of diseases are provoked. It does not disappear from the body without the intervention of therapy up to 10-20 years.

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