Definition of metacercaria : a tailless encysted late larva of a digenetic trematode that is usually the form which is infective for the definitive host.

What is Metacercariae larva?

Definition of metacercaria : a tailless encysted late larva of a digenetic trematode that is usually the form which is infective for the definitive host.

What are the methods of killing the Metacercariae?

We found that a heating process, by boiling or microwaving at 400 or 800 W for at least 5 min, could kill OV metacercariae, and freezing pickled fish at -20 °C for 48 h could kill OV metacercariae in all sizes of fish.

What is the difference between Cercariae and Metacercariae?

At this stage, the cercaria is released from the snail and seeks out a second intermediate host to infect. Metacercaria: … It is in this stage that the parasite infects the definitive human host via ingestion of the snail or other second intermediate host.

Which of the following parasite Metacercariae are found in fish?

Heterophyid metacercariae are usually found encysted in many families of fish, such as: Cobitidae, Cottidae, Cyprinidae, Gobiidae, Mugilidae, Ophicephalidae, Percidae, Plecoglossidae, or Siluridae. Centrocestus formosanus has been encysted experimentally in frogs. The heterophyis cyst is usually small and ovoidal.

What is a sporocyst?

1 : a case or cyst secreted by some sporozoans preliminary to sporogony also : a sporozoan encysted in such a case. 2 : a saccular body that is the first asexual reproductive form of a digenetic trematode, develops from a miracidium, and buds off cells from its inner surface which develop into rediae.

What is the meaning of Digenetic?

Definition of digenetic : of or relating to a subclass (Digenea) of trematode worms in which sexual reproduction as an internal parasite of a vertebrate alternates with asexual reproduction in a mollusk.

Why is trematode life cycle complex?

Complex life cycles are a hallmark of parasitic trematodes. In several trematode taxa, however, the life cycle is truncated: fewer hosts are used than in a typical three-host cycle, with fewer transmission events. Eliminating one host from the life cycle can be achieved in at least three different ways.

What type of organism is clonorchis sinensis?

Clonorchis sinensis, the Chinese liver fluke, is a liver fluke belonging to the class Trematoda, phylum Platyhelminthes. It infects fish-eating mammals, including humans. In humans, it infects the common bile duct and gall bladder, feeding on bile.

What is miracidium larva?

The miracidium is a ciliated, nonfeeding larva (Fig. 9.18). Under favorable conditions, it escapes from the eggshell, usually through the operculum, into the environment. The miracidium is elongated and covered with flattened, ciliated epidermal plates.

Article first time published on

Who is ascariasis?

Ascariasis is the most common roundworm infection. About 10 percent of the developing world is infected with intestinal worms, according to the World Health Organization (WHO). However, parasitic worm infections are not as common in the United States, according to the Centers for Disease Control and Prevention .

What type of parasite is Fasciola hepatica?

Fasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic trematode (fluke or flatworm, a type of helminth) of the class Trematoda, phylum Platyhelminthes. It infects the livers of various mammals, including humans, and is transmitted by sheep and cattle to humans the world over.

What are Operculated eggs?

A total of 460 eggs were isolated of which 108 (30.7%) were operculated, meaning that they were freshly laid eggs, which had not hatched before the host died.

Is cardiac Heterophyiasis fatal?

Heterophyiasis occurs in the Middle East, Far East, and Egypt. The clinical features of the disease include severe and fluctuating abdominal pain and diarrhea. When the eggs of the flukes move into the heart, fatal valvular and myocardial damage may occur.

What stage of trematodes swim in water?

The hatchling is called a miracidium, a free-swimming, ciliated larva. Miracidia will then grow and develop within the intermediate host into a sac-like structure known as a sporocyst or into rediae, either of which may give rise to free-swimming, motile cercariae larvae.

How do you say Miracidium?

noun, plural mi·ra·cid·i·a [mahy-ruh-sid-ee-uh].

Is malarial parasite Digenetic?

> Plasmodium, the malaria parasite is a protozoan parasite and its life cycle is digenetic, as it requires two hosts to complete its life cycle – an invertebrate female anopheles mosquito as its primary host (where sexual reproduction occurs) and a vertebrate (man) as its secondary or intermediate host (where asexual …

Which is Digenetic parasite?

Digenetic parasites need more than one host to complete their life cycle. Plasmodium vivax, the protozoa that carries malaria, is digenetic. In order to complete its life cycle, it must be a parasite of both people and mosquitos.

Is Ascaris Digenetic parasite?

e.g.: Entamoeba histolytica, Ascaris lumbricoides. 5. Digenetic parasite: A parasite that completes its life cycle in two or more hosts.

Which is the first stage of larva of Fasciola?

[Miracidium larva comes out from the egg shell of the fertilized egg by eroding tlie operculum wit11 the help of proteolytic enzyme. It is the first larval stage in the life cycle of F. hepatica. It is a free swimming stage in fresh water.

What is an intermediate host in microbiology?

Definition of intermediate host 1 : a host which is normally used by a parasite in the course of its life cycle and in which it may multiply asexually but not sexually — compare definitive host.

What does Clonorchis sinensis cause?

Clonorchiasis is an infectious disease caused by the Chinese liver fluke (Clonorchis sinensis) and two related species. Clonorchiasis is a known risk factor for the development of cholangiocarcinoma, a neoplasm of the biliary system.

Why is Clonorchis sinensis called Chinese liver fluke?

Parasites – Clonorchis Clonorchis is a liver fluke parasite that humans can get by eating raw or undercooked fish from areas where the parasite is found. Found across parts of Asia, Clonorchis is also known as the Chinese or oriental liver fluke. Liver flukes infect the liver, gallbladder, and bile duct in humans.

What means do Clonorchis sinensis obtain its nutrients?

Clonorchis sinensis is considered a parasite as an adult fluke. It is found in the biliary systems of its hosts, which range from reptiles to humans, absorbing bile as its source of nutrients. ( Buchsbaum, et al., 1987) eats body fluids.

How do you identify a trematode?

Diagnosis of trematode infection is commonly accomplished by identification of eggs in feces or urine. The eggs of most species are structurally distinct and the diagnosis can be made by standard light microscopy. With the exception of fascioliasis, the drug of choice for trematode infections is praziquantel.

Why is Schistosoma a trematode?

There are five species of schistosomes, which are named from the Greek schistos, meaning “split” or “divided,” and soma, meaning “body.” Their classification is based on their flat body structure (thus they are classified in the Phylum Platyhelminthes, meaning broad worm), and they are considered Trematodes (from the …

Is a tapeworm a Cestode?

tapeworm, also called cestode, any member of the invertebrate class Cestoda (phylum Platyhelminthes), a group of parasitic flatworms containing about 5,000 species.

What is Redia larva?

Definition of redia : a larval form of a digenetic trematode (such as a liver fluke) that is produced within a sporocyst, has a mouth, pharynx, and gut, and contains cells which give rise to other rediae or to cercariae — see also redial entry 3.

What is Rhabditiform larva?

Rhabditiform larva is characteristic to nematodes (roundworm). Ascaris is a roundworm. Tapeworm larval stage is called as coenuri; Hydra (cnidarian) lack any larval stage while parenchymula is the free-swimming flagellated larval stage of Leucosolenia (Porifera).

What is oncosphere larva?

An oncosphere is the larval form of a tapeworm once it has been ingested by an intermediate host animal. … In order to become an adult tapeworm, a cysticercus must then be consumed by its definitive host (in either raw or undercooked meat) and establish itself by anchoring in that host’s digestive tract.

Is Ascaris a roundworm?

Ascariasis (as-kuh-RIE-uh-sis) is a type of roundworm infection. These worms are parasites that use your body as a host to mature from larvae or eggs to adult worms. Adult worms, which reproduce, can be more than a foot (30 centimeters) long.