''Fasciolopsis'' () is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

trematode Trematoda is a Class (biology), class of flatworms known as trematodes, and commonly as flukes. They are obligate parasite, obligate Endoparasites, internal parasites with a complex biological life cycle, life cycle requiring at least two Host ( ...

s. They are also known as giant intestinal flukes. Only one

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

is recognised: ''Fasciolopsis buski''. It is a notable parasite of medical importance in humans and veterinary importance in pigs. It is prevalent in Southern and Eastern Asia. The term for infestation with ''Fasciolopsis'' is

fasciolopsiasis Fasciolopsiasis results from an infection by the trematode '' Fasciolopsis buski'', the largest intestinal fluke of humans, growing up to long. Signs and symptoms Most infections are light, almost asymptomatic. In heavy infections, symptoms ca ...

''Fasciolopsis buski''

''Fasciolopsis buski'' is commonly called the giant intestinal fluke, because it is an exceptionally large parasitic fluke, and the largest known to parasitise humans. Its size is variable and a mature specimen might be as little as 2 cm long, but the body may grow to a length of 7.5 cm and a width of 2.5 cm. It is a common

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

of humans and pigs and is most prevalent in Southern and

Southeastern Asia Southeast Asia is the geographical southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Australian mainland, which is part of Oceania. Southeast Asia is ...

. It is a member of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Fasciolidae Fasciolidae is a family of trematodes and includes several parasites involved in the veterinary and medical sciences, which cause the disease Fasciolosis. Fasciolidae is divided into five genera by Olson et al. 2003. The family's various species ...

in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Plagiorchiida Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few significant parasites of humans. The following families are placed here, ...

. The Echinostomida are members of the

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

Trematoda Trematoda is a class of flatworms known as trematodes, and commonly 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 a mol ...

, the flukes. The fluke differs from most species that parasitise large mammals, in that they inhabit the gut rather than the liver as ''

Fasciola ''Fasciola'', commonly known as the liver fluke, is a genus of parasitic trematodes. There are three species within the genus ''Fasciola'': ''Fasciola nyanzae,'' ''Fasciola'' ''hepatica'' and ''Fasciola'' ''gigantica''. ''Fasciola hepatica'' an ...

'' species do. ''Fasciolopsis buski'' generally occupies the upper region of the

small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from food takes place. It lies between the stomach and large intes ...

, but in heavy infestations can also be found in the

stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...

and lower regions of the intestine. ''Fasciolopsis buski'' is the cause of the pathological condition

. In London,

George Busk George Busk FRS FRAI (12 August 1807 – 10 August 1886) was a British naval surgeon, zoologist and palaeontologist. Early life, family and education Busk was born in St. Petersburg, Russia. He was the son of the merchant Robert Busk and h ...

first described ''Fasciolopsis buski'' in 1843 after finding it in the

duodenum The duodenum is the first section of the small intestine in most vertebrates, including mammals, reptiles, and birds. In mammals, it may be the principal site for iron absorption. The duodenum precedes the jejunum and ileum and is the shortest p ...

of a sailor. After years of careful study and self experimentation, in 1925, Claude Heman Barlow determined its life cycle in humans.

Morphology

''Fasciolopsis buski'' is a large,

dorsoventrally Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

flattened fluke characterized by a blunt

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

end, undulating, unbranched ceca (sac-like cavities with single openings), tandem

dendritic Dendrite derives from the Greek word "dendron" meaning ( "tree-like"), and may refer to: Biology *Dendrite, a branched projection of a neuron *Dendrite (non-neuronal), branching projections of certain skin cells and immune cells Physical *Dendri ...

testes A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of androgens, primarily testosterone. The ...

, branched

ovaries The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...

, and ventral suckers to attach itself to the

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County * Host Island, in the Wilhelm Archipelago, Antarctica People * ...

. The

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

is larger than the oral sucker. The fluke has extensive vitelline follicles. It can be distinguished from other fasciolids by a lack of

cephalic A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...

cone or "shoulders" and the unbranched ceca.

Life cycle

Adults produce over 25,000 eggs every day; these take up to seven weeks to mature and hatch at 27–32 °C. Immature, un

embryonated Embryonated, unembryonated and de-embryonated are terms generally used in reference to eggs or, in botany, to seeds. The words are often used as professional jargon rather than as universally applicable terms or concepts. Examples of relevant fields ...

eggs are discharged into the intestine and stool. In two weeks, eggs become embryonated in water, and after about seven weeks, tiny parasitic organisms called

miracidia The miracidium is the second stage in the life cycle of trematodes. When trematode eggs are laid and come into contact with fresh water, they hatch and release miracidium. In this phase, miracidia are ciliated and free-swimming. This stage is comp ...

hatch from the eggs, which then go on to invade a suitable

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

intermediate host. Several species in the genera ''

Segmentina ''Segmentina'' is a genus of very small, air-breathing, freshwater snails, aquatic gastropod mollusks or micromollusks in the family Planorbidae, the ramshorn snails. Albrecht et al. (2007)Albrecht C., Kuhn K. & Streit B. (2007). "A molecular ...

'' and '' Hippeutis'' serve as intermediate hosts. In the snail the parasite undergoes several developmental stages (sporocysts, rediae, and cercariae). The

cercariae A cercaria (plural cercariae) is a larval form of the trematode class of parasites. It develops within the germinal cells of the sporocyst or redia. A cercaria has a tapering head with large penetration glands. It may or may not have a long swim ...

are released from the snail and encyst as

metacercariae Trematodes are parasitic flatworms of the class ''Trematoda'', specifically parasitic flukes with two Sucker (zoology), suckers: one ventral and the other Mouth, oral. Trematodes are covered by a Tegument (helminth), tegument, that protects the o ...

on aquatic plants such as

water chestnut Water chestnut may refer to either of two plants, both used in Chinese cuisine: * ''Eleocharis dulcis'', or Chinese water chestnut, is eaten for its crisp corm * Water caltrop, ''Trapa natans'', is eaten for its starchy seed See also * Chinese cui ...

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 nut, mustache nut, singhara nut or wate ...

, lotus,

bamboo Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...

, and other edible plants. The

mammalian A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

final host becomes infected by ingesting

on the aquatic plants. After ingestion, the metacercariae encyst in the

in about three months and attach to the intestinal wall. There they develop into adults (20 to 75 mm by 8 to 20 mm) in approximately three months, remaining attached to the intestinal wall of the mammalian hosts (humans and pigs). The adults have a life span of about one year.

Pathogenesis

Humans become infected by ingesting

present on contaminated

aquatic plant Aquatic plants, also referred to as hydrophytes, are vascular plants and Non-vascular plant, non-vascular plants that have adapted to live in aquatic ecosystem, aquatic environments (marine ecosystem, saltwater or freshwater ecosystem, freshwater ...

s, like water chestnuts and watercress, or by consuming water contaminated with the parasite. Once ingested, the metacercariae

encyst A microbial cyst is a resting or dormant stage of a microorganism, that can be thought of as a state of suspended animation in which the metabolic processes of the cell are slowed and the cell ceases all activities like feeding and locomotion. ...

in the

and attach to the

jejunum The jejunum is the second part of the small intestine in humans and most higher vertebrates, including mammals, reptiles, and birds. Its lining is specialized for the absorption by enterocytes of small nutrient molecules which have been pr ...

and

ileum The ileum () is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may ...

of the intestinal wall. The flukes then use their

oral sucker A sucker in zoology is a specialised attachment organ of an animal. It acts as an adhesion device in parasitic worms, several flatworms, cephalopods, certain fishes, amphibians, and bats. It is a muscular structure for suction on a host or substra ...

to stick to the intestinal mucosa- in which can cause mechanical damage and irritation to the lining of the intestine. This attachment can lead to ulcerations, inflammation, and local tissue damage. The pathogenesis results in various symptoms including, but not limited to: *

Abdominal pain Abdominal pain, also known as a stomach ache, is a symptom associated with both non-serious and serious medical issues. Since the abdomen contains most of the body's vital organs, it can be an indicator of a wide variety of diseases. Given th ...

Diarrhea Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...

Nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

Vomiting Vomiting (also known as emesis, puking and throwing up) is the 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, gastroenteritis, pre ...

Fever Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with Human body temperature, body temperature exceeding the normal range caused by an increase in the body's temperature Human body temperature#Fever, s ...

Weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other conn ...

Allergic reactions Allergies, also known as allergic diseases, are various conditions caused by hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic dermatitis, alle ...

due to the presence of the parasite In severe cases or with prolonged infections, there can be nutritional deficiencies due to

malabsorption Malabsorption is a state arising from abnormality in absorption of food nutrients across the gastrointestinal (GI) tract. Impairment can be of single or multiple nutrients depending on the abnormality. This may lead to malnutrition and a varie ...

caused by the intestinal damage. In other cases, secondary bacterial infections might occur due to the disruption of the intestinal barrier by the fluke, leading to further opportunistic infections. Adult flukes reside in the small intestine, where they mature and produce eggs. These eggs are then passed into the host's feces where they will continue the life cycle of the parasite. Treatment involves

anthelmintic 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 without causing significant damage to the host. They may also ...

medications to rid the flukes from the intestines. Early diagnosis and treatment are essential in preventing further complications an progression of the disease.

Diagnosis

Examination of stool samples microscopically to identify parasite eggs can aid in the diagnosis of this parasite. However, due to intermittent egg shedding, multiple stool samples may be necessary for an accurate diagnosis. The WHO recommends the Kato-Katz technique as the method of choice for fascioliasis diagnosis attending to its ease of use and reproducibility, and its enhanced sensitivity compared with the observation of eggs in fresh faeces. Enzyme-linked immunosorbent assay (

ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay is a solid-phase type of enzyme immunoassay (EIA) to detect the presence of ...

) or other serological tests can also help identify specific

antibodies An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...

against Fasciolopsis buski antigens in the blood. In some cases, imaging techniques like

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...

might also be used to visualize the flukes within the intestines.

Control

Promoting proper hygiene, clean water sources, and safe food practices to prevent contamination by infective stages of the parasite. Thoroughly cooking aquatic plants and ensuring proper washing and cleaning of vegetables and fruits to remove potential infective stages. Educating communities about the risks of consuming contaminated water, raw or undercooked plants, and promoting awareness of the disease can also play a huge role in containing the spread of this parasite. If contracted, another way to help control is the use of anthelmintic medications.

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

is the type of medication currently used to treat such infections. These are to be prescribed by healthcare professionals for infected individuals to eradicate the parasites from the body.

Vaccination

Vaccination against

infections like

fascioliasis Fasciolosis is a parasitic worm infection caused by the common liver fluke ''Fasciola hepatica'' as well as by '' Fasciola gigantica''. The disease is a plant-borne trematode zoonosis, and is classified as a neglected tropical disease (NTD). I ...

and

is still an area of ongoing research. Development of effective vaccines for these parasites remains a challenge due to the complex life cycles and various stages of the parasites involved. Researchers continue to explore different approaches and antigens for potential vaccine candidates.

References

External links

Centers for Disease Control and Prevention (CDC)

BioLib

The Taxonomicon

ZipcodeZoo

*Fasciolopsiasis in children: Clinical, Sociodemographic Profile and outcome. Indian Journal of Medical Microbiology2017 vol 35, issue 4 page 551-554 DOI:10.4103/ijmm.IJMM_17_7 * http://www.ijmm.org/text.asp?2017/35/4/551/224440
Fascioliasis and fasciolopsiasis: Current knowledge and future trends

Fasciola hepatica vaccine: we may not be there yet but we're on the right road
*

The Journal of Parasitology The ''Journal of Parasitology'' is a peer-reviewed medical journal covering research on parasites published bimonthly by Allen Press on behalf of the American Society of Parasitologists. Content includes research articles, brief research notes, a ...

{{Taxonbar, from=Q3279537 Fasciolidae Trematode genera Monotypic platyhelminthes genera Parasitic helminths of humans