There are more than 7,000 species of flatworms in nature. The lanceolate fluke, or, as it is also called, the lanceolate fluke, is one of them. It is distributed across all continents. Fortunately, this parasite rarely settles in humans, but it is very dangerous for domestic animals, as it causes serious illness in them, and sometimes even death. In the process of evolution, the worm has adapted to "live" in different hosts. Its development cycle is complex, but well debugged. People should make a lot of efforts to keep their animals and themselves from infection.
Lancet fluke. Morphophysiological characteristics
This type of fluke belongs to the flatworm trematode. Its dimensions are relatively small - the length of the body is not more than 10 mm, and the width is 3 mm. Outwardly, the creature resembles a lancet, hence the name of the parasite. An adult formed worm (marita) is armed with two suckers - a larger abdominal one and a slightly smaller one - oral ones. The fluke's body is imprisonedinto the muscular sac. Muscles have three layers - external circular, internal longitudinal and transverse. The body of the worm is flat, not divided into segments. Its internal organs are represented by the digestive, nervous, excretory and reproductive systems. Excretory and nervous are quite simple. The digestive system includes the mouth, pharynx, esophagus and intestines, two branches of which stretch along the sides of the body and end blindly. The parasite removes undigested food through the mouth. The lanceolate fluke has a rather complex structure of the reproductive system. It is represented by two testes with vas deferens, one round, relatively small ovary, oviduct, ootype and uterus, which occupies approximately 2/3 of the body volume.
Reproduction
According to the type of device of the reproductive system, the lanceolate fluke belongs to hermaphrodites. Its reproduction occurs only in the final, third host. The seed of a sexually mature individual of the worm enters the cirrus (ejaculatory organ) through the vas deferens, and then moves to the copulatory (cumulative) organ. The ootype is a special chamber with a dense shell. The ejaculatory canal of the male genital organs, the duct of the oviduct, the vitelline glands and the canal of the uterus lead into it. In the ootype, the eggs are fertilized, coated with yolk elements and a shell. The formed eggs enter the uterus, where, moving towards the uterine opening, they mature and go outside into the body of the victim. Having moved into her intestines, they are excreted with feces into the environment. Wednesday.
Eggs
A lanceolate fluke whose egg morphology is such that by the time it hatches the larva (miracidium) is already fully formed in it, it needs several hosts. In shape, the eggs of the parasite are oval, covered with very dense shells, with a cap at one end. Their dimensions vary in length from 0.038 to 0.045 mm, and in width from 0.022 to 0.03 mm. Color - from dark yellow to brown. The lanceolate fluke, like all parasitic worms, is extremely prolific. One individual is capable of producing up to a million eggs per week. It is not for nothing that they have two dense shells, because after entering the environment they will have to wait for their first owner, perhaps survive drought, rainstorms, heat or cold.
First owner
The entire development cycle of the lanceolate fluke takes place on land. Snails and slugs live in the grass, which, with their rough, like a grater, tongues, remove plant tissues. In this case, the eggs of the worm enter the intestines of the molluscs. There, miracidia hatch from them. Their body is partially covered with cilia, and on the head cone there is a formation - stylet. With its help, each larva seeps through the walls of the victim's intestines into the spaces between its organs, where it is freed from cilia and turns into a maternal sporocyst. She loses almost all organs, except for germ cells. Its purpose and meaning is to create as many daughter larvae as possible so that the lanceolate fluke does not stop its genus. Its life cycle depends on hundreds of accidents,for out of the millions of eggs that are on the grass, only a negligible part finds a host. Reproduction occurs in the virgin way (parthenogenesis). As a result, new larvae (redia) appear. They have a pharynx with which they suck fluids from their host's body. In the future, cercariae are born from the redia. With the help of their muscular system, they reach the lungs of the mollusk, where they stick together into spherical lumps covered with mucus. Sometimes they can count up to 400 individuals. The snail breathes them out onto the grass. There, the mucus hardens, protecting the cercariae from adverse effects.
Second owner
The development cycle of the lanceolate fluke continues in ants that eat balls with larvae. Once in the intestines of the next victim, the mucus dissolves, and the cercariae form cysts with new larvae inside. These are metacercariae. It is believed that some cercariae in the body of an ant move towards its nerve nodes - the ganglia, and having penetrated there, they paralyze the insect when the air temperature drops. This hypothesis is confirmed by the behavior of sick ants, which live as usual on a warm day, and in the evening or in cloudy, cold weather they freeze on blades of grass, as if paralyzed. Mammals (ungulates, hares, dogs and others), eating grass, swallow such immovable ants, and with them the larvae of the parasite. Once in the organism of the final host, the metacercariae migrate to its liver, where a young lanceolate fluke is formed from them. Life cycle of the parasite from now onrepeats.
Animal dicroceliosis
All animals that eat infected ants get dicroceliasis. In dogs, this happens when eating food that contains ants. Pets become lethargic, emaciated, stunted. Their mucous membranes become icteric. The result of the disease is cirrhosis of the liver or inflammation of the bile ducts.
Signs of dicroceliasis in ungulates, e.g. goats, sheep:
- oppression;
- hair loss, its dullness;
- jaundice of mucous membranes;
- constipation or diarrhea;
- coma (immobility with the neck turned to the side and eyes closed); the incidence of diseased livestock is quite high.
That's what a dangerous parasite is the lanceolate fluke. The structure and features of its eggs and larvae allow them to withstand environmental temperatures from +50 to -50 degrees. They die only under conditions when the mentioned indicators of the temperature regime increase significantly. And they can live in feces for about a year.
Human Dicroceliasis
No matter how prolific the lanceolate fluke is, it rarely causes disease in humans, because this requires penetration into the stomach of sick ants. When eating the liver of infected animals, a false infection occurs that does not require treatment. And, nevertheless, people get sick with dicroceliosis. Infection occurs when ants get on a standardhuman food (bread, vegetables, and so on), by eating unwashed meadow sorrel, by placing blades of grass on which there are ants in the mouth, and so on. Disease symptoms:
- discomfort and pain in the liver area;
- diarrhea or constipation;
- weight loss;
- jaundice of mucous membranes.
Treatment
The lanceolate fluke parasitizes only in the liver and bile ducts. People are being treated with Triclobendazole and Praziquantel. No hospitalization required.
In case of false dicroceliosis, it is recommended to refuse to eat the meat of sick animals. Medicines are not used in this case.
Domestic ungulates are treated with "Polytrem", "Panacur". Doses are prescribed based on the weight of the animal. The medicine is mixed with food and given in the morning. There are also drugs that are administered intramuscularly.
Hexichol is used to treat dogs, and Karsil is used to normalize liver function.
Prevention
In animals, dicroceliasis is severe and often ends in death. Part of the reason for this is that signs of the disease appear when the concentration of the worm in the liver reaches high numbers (for example, sheep have more than 10,000 individuals). Therefore, in order not to cause problems with the lanceolate fluke, prevention plays a decisive role. It consists in the deworming of animals. As for sheep and other ruminants, it is carried out at 1.5 years, at 3, 5 and 7 years. It is also necessary to monitor the state of pastures, eliminatethe supposed habitats of mollusks are bushes, stones. Manure on the fields should be taken out in a biothermally decontaminated way.
In humans, outbreaks of dicroceliasis are most often observed in regions where it is customary to eat insects, and among them ants. Also in some countries they are used in traditional medicine. In order not to “catch” a fluke, a person needs to follow simple hygiene rules.
