Development cycle of the hepatic fluke
The development cycle of the hepatic fluke differs depending on the type of worms: hepatic fluke, lanceolate fluke, and hepatic fluke, which causes opisthorchiasis
Content:
- Development cycle of giant fluke and hepatic fluke
- Development cycle of the hepatic fluke causing opisthorchiasis
- Lanceolate fluke development cycle
- Who is the intermediate host of the liver fluke?
Development cycle of giant fluke and hepatic fluke
Adult worms parasitize in the bile excretory system of humans or animals, releasing eggs, which are released into the environment along with the feces of the final host.
When eggs enter fresh water, larvae (miracidium) emerge from them. They penetrate the body of gastropods, where they transform into sporocysts, and then into cercariae. After 2 months, the cercariae leave the body of the intermediate host and re-enter the water. Here they turn into adolescaria, these larvae are ready for the invasion of the final host. It is in this state that they attach to the water film, or to the surfaces of plants.
After entering the gastrointestinal tract of an animal or person, the larvae penetrate through the walls of the stomach into the abdominal cavity. There they find the liver, penetrate into its parenchyma, reaching the bile ducts.
Sometimes the larvae migrate through the circulatory system, reaching the bile ducts through the portal and intestinal veins. For 3-4 months, the larvae mature in the bile ducts, after which they begin to release eggs into the external environment.
The hepatic and giant fluke can parasitize in the human body for 10 or more years.
Development cycle of the hepatic fluke causing opisthorchiasis
With the feces of the final host, which is an animal or a person, the eggs of the parasites go out into the external environment and enter the reservoir. There they are swallowed by freshwater mollusks, in the body of which the larvae undergo certain changes and turn into cercariae. Two months later, the parasite leaves the mollusk and invades the body of the fish on its own. Larvae of worms prefer fish of the carp family.
In the body of a fish, the cercariae throws off its tail and becomes mobile, transforming into a metacercaria. Already six weeks after being in the body of a fish, the face becomes invasive.
After entering the stomach and upper small intestine of the permanent host (human or animal), the larva enters the gallbladder and liver. The parasite will reach puberty in two weeks. Trematodes can exist in the human body from 10 to 30 years, feeding on erythrocytes, epithelial cells and mucus secreted by the biliary tract.
Lanceolate fluke development cycle
In the body of a permanent host (human or animal), a sexually mature parasite parasitizes, which, together with feces, releases eggs into the external environment. They enter the soil and are swallowed by terrestrial molluscs. In their body, a cercarium is formed, which goes out into the external environment.
The cercarium is eaten by ants and transforms into a metacercarium in their body. After that, the ants become infectious. When the larvae enter the digestive tract (swallowed together with ants), they penetrate the bile ducts and the gallbladder of the final host, mature there and begin to release eggs into the external environment.
Who is the intermediate host of the liver fluke?
The intermediate host of the hepatic fluke, namely the giant fluke and the hepatic fluke, are gastropods. Most often it is a pond snail of the genus Galba. They live in large numbers in stagnant bodies of water, where the water warms up well. These can be low-lying wetlands and pastures. Interestingly, in Australia there are no mollusks of the species Lamnea truncaltula, but the liver fluke is widespread. The parasite was introduced to the continent with domestic animals and managed to find a new intermediate host - the mollusk L. Tomentosa.
Inside the molluscs, the larvae become sporocysts, and then the stages of the caudate cercariae grow. In the body of gastropods, the liver fluke spends from 1 to 2 months.
The hepatic fluke, provoking opisthorchiasis, requires a change of two intermediate hosts. The first of them is a freshwater mollusk of the genus Bithynia inflate, and the second intermediate host is fish from the cyprinid family (ide, roach, tench, verkhovka, etc.).
The intermediate host of the lanceolate fluke is terrestrial mollusks, and after them - ants.
Author of the article: Danilova Tatyana Vyacheslavovna | Infectionist
Education: in 2008 received a diploma in the specialty "General Medicine (General Medicine)" at the Russian Research Medical University named after NI Pirogov. Immediately passed an internship and received a diploma of a therapist.
