Pigs, Monkeys, Rats, Fish, and other fish-eating animals Vector No known Humans are considered an accidental host because the parasite can survive without the existence of man. However, the snail intermediate host is necessary in the development of the parasite. Hominis are passed in feces unfertilized usually into some kind of water source where they are ingested by the snail intermediate host. The eggs hatch and release miracidium which develop from there into the sporocyst stage followed by one or more generations of redia.

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Their description of the internal structure was inaccurate and incomplete. They claimed that the parasite had one testis and one ovary. They placed it in the genus Amphistomum, because of its obvious location of posterior sucker; the species was named Amphistomum hominis, as it was found in human.

Fischoeder recognised the affinity with other species and tentatively placed it in the genus Gastrodiscus Leuckart, However, the generic name was largely recognised as a synonym ; it was then known as Amphistomum Gastrodiscus hominis.

With a fresh look, J. Stephens re-described the parasite in , and clearly noted the overlooked relatively small ovary and interpretation of the posterior testis as an ovary in the original description. Leiper, re-examined the parasite in He noted the distinctive characters such as a tuberculated genital cone, the position of the genital orifice, a smooth ventral disc, and the testes in tandem position. These outstanding features prompted him to create an entirely new genus, Gastrodiscoides, for the specimen.

It was later observed that the parasite was much more common to pigs and other mammals than in humans. The first report of infection of pigs was in Cochinchina , Vietnam , in Then a large number of living flukes was recovered from dead Napu mouse-deer at the Zoological Gardens of the Zoological Society of London. Buckley, at the London School of Hygiene and Tropical Medicine where he was then a Milner Research Fellow , whose descriptions were based on high incidence of the parasitism among the Assamese in India.

The body is bilaterally symmetrical and is acoelomate. It is dorsoventrally flatted, with a unique pyramidal shape. The body is covered by a tegument bearing numerous tubercles. The bladder is in the middle behind the ventral sucker. The genus is hermaphrodite , as both male and female reproductive system are present. The disc-shaped body is divisible into anterior conical and posterior discoidal regions.

The anterior region is a conical projection bearing a prominent oral sucker. It is an amphistome worm such that the ventral sucker is close to the posterior end. Ventral surface contains a specialised region of the tegument. Ciliated and non-ciliated papillae are arranged around the oral sucker. The large excretory bladder is in the middle, behind the ventral sucker.

The species, being hermaphrodite , has both male and female reproductive systems , arranged in the posterior region. The testes lie in alongside the bifurcation of the caeca, and a common genital pore is on the cone just anterior to the bifurcation. The oval-shaped ovary lies just posterior to the testes in the middle, and the loosely coiled uterus opens to the genital pore. Vitelline glands are scattered around the caeca. Infection causes a helminthic disease called gastrodiscoidiasis.

As a hermaphrodite, eggs are produced by self-fertilisation and are released along the faeces of the host. Each egg contains about 24 vitelline cells and a central unembryonated ovum. Eggs in a wet environment hatch into miracidia in 9—14 days.

In water, eggs hatch into miracidia , which then infect a mollusc , in which larval development and fission occurs. The miracidium grows into the sporocyst stage. It is generally conceived that the unfertilised eggs are ingested by the snail, but there has been no direct observation.

In an experimental infection of the mollusc Helicorbis coenosus, miracidum develops into cercaria after 28— days of ingestion. Infective cercariae are produced and are released on water plants or directly infect other aquatic animals, such as fish. The complete life cycle is not yet observed in nature, [18] and the tiny snail, H. In some circumstances, fishes and other aquatic animals are found to be infected.

It is hypothesised that the free cercaria in water bodies accidentally find and penetrate these animals as second intermediate host, where they encsyt as metacercaria. These are directly infective to mammals upon consumption, while they get attached to vegetation, where night soil is used. Humans ingest the metacercaria either by the infected fish or contaminated vegetable. The parasite travels through the digestive tract into the duodenum , then continues down to reach the caecum, where it self-fertilizes and lay eggs, continuing the cycle.

Heavy infection in humans is suspected to cause diarrhoea , fever , abdominal pain, colic , malnutrition , anaemia , and even death. It is suspected to cause diarrhoea , fever , abdominal pain, colic , and an increased mucous production. In severe cases, where there are large amounts of eggs present, tissue reactions can occur in the heart or mesenteric lymphatics, and even death may occur if left neglected.

Indeed, a number of mortality among Assamese children is attributed to this infection. The submucosa can show oedema and thickening, resulting in a subacute inflammation of the caecum and mucoid diarrhoea. Later investigations revealed that it is widespread, and is further spread by infected persons to other parts of the world, such as Guyana.

Infection in both humans and animals is most common through the ingestion of vegetation found in contaminated water. It is also assumed that transmission from infected fish that is under-cooked or eaten raw, as common among southeast Asian. The child quickly recovered after proper medication. Adult worms are easily identified from other helminths by their distinctive appearance. The eggs are readily distinguished from those of other trematodes by their rhomboid shape and distinct green colour.

Patients do not often directly show any symptoms, and if one appears, it indicates that the infection is already at a very high level. There is no prescribed treatment, but the traditional practice of soap enema has been very effective in removing the worms. Some drugs that have been proven effective are tetrachloroethylene , at a dosage of 0.

Night soil should never be used as a fertilizer because it could contain any number of parasites. Vegetables should be washed thoroughly, and meat properly cooked.



Kajigrel Severe Fasciola and Gastrodiscoides infestation is due to repeated consumption of the metacercaria larva from aquatic plants. With a fresh look, J. Indeed, a number of mortality among Assamese children is attributed to this homknis. Gastrodiscoides hominis Fauna Gwstrodiscoides This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


A Description of Gastrodiscoides hominis, from the Napu mouse deer


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