Fasciolopsiasis results from an

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

by the

trematode Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host ...

Fasciolopsis buski ''Fasciolopsis'' () is a genus of trematodes. They are also known as giant intestinal flukes. Only one species is recognised: ''Fasciolopsis buski''. It is a notable parasite of medical importance in humans and veterinary importance in pigs. I ...

'', the largest

intestinal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...

fluke Fluke may refer to: Biology * Fluke (fish), a species of marine flatfish * Fluke (tail), the lobes of the tail of a cetacean, such as dolphins or whales, ichthyosaurs, mosasaurs Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ...

human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

s (up to 7.5 cm in length).

Signs and symptoms

Most infections are light, almost

asymptomatic In medicine, any disease is classified asymptomatic if a patient tests as carrier for a disease or infection but experiences no symptoms. Whenever a medical condition fails to show noticeable symptoms after a diagnosis it might be considered asy ...

. In heavy infections, symptoms can include

abdominal pain Abdominal pain, also known as a stomach ache, is a symptom Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than ...

, chronic

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, th ...

ascites Ascites is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdominal size, increased weight, ab ...

, toxemia, allergic responses, sensitization caused by the absorption of the worms' allergenic metabolites can lead to intestinal obstruction and may eventually cause death of the patient.

Cause

The parasite infects an amphibic

snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...

(''

Segmentina nitidella ''Segmentina mica'' is a species of gastropods belonging to the family Planorbidae Planorbidae, common name the ramshorn snails or ram's horn snails, is a family of air-breathing freshwater snails, aquatic pulmonate gastropod molluscs. Unli ...

, Segmentina hemisphaerula, Hippeutis schmackerie,

Gyraulus ''Gyraulus'' is a genus of small, mostly air-breathing, freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails. The genus ''Gyraulus'' is known from the Early Cretaceous to the present. Fossi ...

Lymnaea ''Lymnaea'' is a genus of small to large-sized air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the subfamily Lymnaeinae ( of the family Lymnaeidae, the pond snails.Bouchet, P.; Rosenberg, G. (2013). Lymnaea Lamarck, 179 ...

, Pila,

Planorbis ''Planorbis'' is a genus of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails, or planorbids. All species in this genus have sinistral or left-coiling shells.Bouchet, P.; Rosen ...

(

Indoplanorbis ''Indoplanorbis'' is a genus of air-breathing freshwater snail. Its only member species is ''Indoplanorbis exustus'', an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails. The species is widely distributed ac ...

)'') after being released by infected mammalian feces; metacercaria released from this

intermediate host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...

encyst on

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

s like

water spinach ''Ipomoea aquatica'', widely known as water spinach, is a semi- aquatic, tropical plant grown as a vegetable for its tender shoots. ''I. aquatica'' is generally believed to have been first domesticated in Southeast Asia. It is widely cultivate ...

, which are eaten raw by pigs and humans. Water itself can also be infective when drunk unboiled ("Encysted cercariae exist not only on

s, but also on the surface of the water.")

Diagnosis

Microscopic identification of eggs, or more rarely of the adult flukes, in the stool or

vomitus Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteri ...

is the basis of specific diagnosis. The eggs are indistinguishable from those of the very closely related ''

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, inc ...

'' liver fluke, but that is largely inconsequential since treatment is essentially identical for both.

Prevention

Infection can be prevented by immersing vegetables in boiling water for a few seconds to kill the infective metacercariae, avoiding the use of untreated feces ("nightsoil") as a fertilizer, and maintenance of proper sanitation and good hygiene. Additionally,

control should be attempted.

Treatment

Praziquantel Praziquantel (PZQ), sold under the brandname Biltricide among others, is a medication used to treat a number of types of helminthiasis, parasitic worm infections in mammals, birds, amphibians, reptiles, and fish. In humans specifically, it is us ...

is the

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

of choice for treatment. Treatment is effective in early or light infections. Heavy infections are more difficult to treat. Studies of the effectiveness of various drugs for treatment of children with ''F. buski'' have shown

tetrachloroethylene Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and many other names (and abbreviations such as "perc" or "PERC", and "PCE"), is a chlorocarbon with the formula Cl2C=CCl2 . It is a colorless li ...

as capable of reducing faecal egg counts by up to 99%. Other

anthelmintics Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may a ...

that can be used include

thiabendazole Tiabendazole (INN, BAN), also known as thiabendazole (AAN, USAN) or TBZ and the trade names Mintezol, Tresaderm, and Arbotect, is a preservative, an antifungal agent, and an antiparasitic agent. Uses Preservative Tiabendazole is used primar ...

mebendazole Mebendazole (MBZ), sold under the brand name Vermox among others, is a medication used to treat a number of parasitic worm infestations. This includes ascariasis, pinworm infection, hookworm infections, guinea worm infections, hydatid disea ...

levamisole Levamisole, sold under the brand name Ergamisol among others, is a medication used to treat parasitic worm infections, specifically ascariasis and hookworm infections. It is taken by mouth. Side effects may include abdominal pain, vomiting, ...

and

pyrantel pamoate Pyrantel is a medication used to treat a number of parasitic worm infections. This includes ascariasis, hookworm infections, enterobiasis (pinworm infection), trichostrongyliasis, and trichinellosis. It is taken by mouth. Side effects inclu ...

Oxyclozanide Oxyclozanide is a salicylanilide anthelmintic. It is used in the treatment and control of fascioliasis in ruminants mainly domestic animals such as cattle, sheep, and goats. It mainly acts by uncoupling of oxidative phosphorylation in flukes. Alon ...

hexachlorophene Hexachlorophene, also known as Nabac, is an organochlorine compound that was once widely used as a disinfectant. The compound occurs as a white odorless solid, although commercial samples can be off-white and possess a slightly phenolic odor. It ...

and nitroxynil are also highly effective.

Epidemiology

''F. buski'' is endemic in

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

including

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

, and

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. It has an up to 60% prevalence in worst-affected communities in southern and eastern

and mainland

and has an estimated 10 million human infections. Infections occur most often in school-aged children or in impoverished areas with a lack of proper sanitation systems. A study from 1950s found that ''F. buski'' was endemic in central Thailand, affecting about 2,936 people due to infected aquatic plants called

water caltrop The water caltrop is any of three extant species of the genus ''Trapa'': ''Trapa natans'', ''Trapa bicornis'' and the endangered ''Trapa rossica''. It is also known as buffalo nut, bat nut, devil pod, ling gok (Chinese: 菱角), ling nut, lin kok ...

s and the snail hosts which were associated with them. The infection, or the eggs which hatch in the aquatic environment, were correlated with the water pollution in different districts of Thailand such as Ayuthaya Province. The high incidence of infection was prevalent in females and children ages 10–14 years of age.

References

External links

{{Helminthiases Helminthiases Fasciolidae Zoonoses cs:Fasciolopsis buski