Fasciolopsis
Encyclopedia
Fasciolopsis is a genus
of trematodes. It consists only of two species
, F. buski and F. Magna, of which, F. buski, is more notable in terms of prevalence
and pathogenicity
as it causes the disease fasciolopsiasis
.
Fasciolopsis buski is commonly called the giant intestinal fluke
, being the largest known parasitic fluke
in humans. The body can be up to 7.5 cm in length and 2.5 cm in width. It is a common parasite of humans and pigs
and is most prevalent in Asia
, mainly central
and southeast Asia
. It belongs to the class
Trematoda
, family
Fasciolidae. The reason for its common name is due to the fact that it is one of the largest flukes
to infect humans. The worm
inhabits the upper region of the small intestine
and, when abundant, can also be found in the lower areas of the intestine
and the stomach
. Fasciolopsis buski is the cause of the disease fasciolopsiasis
.
In London, George Busk
first described F. buski in 1843 after finding it in the duodenum
of a sailor. In 1925, Barlow first determined its life cycle in humans
that is characterized by a blunt anterior end, undulating, unbranched ceca
(sac-like cavity with a single opening), tandem, dendritic testes, branched ovaries, and ventral suckers
to attach itself to the host
. The acetabulum
is larger than the oral sucker
. It has extensive vitelline
follicles. It can be distinguished from other fasciolids by a lack of cephalic cone or "shoulders" and the unbranched ceca
.
Adults produce over 25,000 eggs every day which take up to seven weeks to mature and hatch at 27-32°C. Immature, unembryonated eggs are discharged into the intestine
and stool
. In two weeks, eggs become embryonated in water, and after about seven weeks, eggs release tiny parasitic organisms called miracidia, which invade a suitable snail intermediate host. Several species
of genera
Segmentina
and Hippeutis
serve as intermediate hosts. In the snail
the parasite undergoes several developmental stages (sporocysts, rediae, and cercariae). The cercariae are released from the snail and encyst as metacercariae on aquatic plants such as water chestnut
, water caltrop
, lotus, bamboo
, and other edible plants. The mammalian host, or the final host, becomes infected by ingesting metacercariae on the aquatic plants. After ingestion, the metacercariae excyst in the duodenum
in about three months and attach to the intestinal wall
. There they develop into adult flukes
(20 to 75 mm by 8 to 20 mm) in approximately 3 months, attached to the intestinal wall
of the mammalian hosts (humans and pigs
). The adults have a life span
of about one year.
. In heavy infections, symptoms can include abdominal pain
, chronic
diarrhea
, anemia
, ascites
, toxemia
, allergic responses
, sensitization caused by the absorption of the worms allergenic metabolites (may eventually cause death of patient), and intestinal obstruction.
, in the stool
or vomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of Fasciola hepatica
.
is the drug
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
as capable of reducing faecal egg counts by up to 99%. Other anthelmintics that can be used include thiabendazole
, mebendazole
, levamisole
and pyrantel pamoate
. oxyclozanide
, hexachlorophene
and nitroxynil are also highly effective.
is known to help, and for the eggs cloves are used. Flemingia vestita and Lysimachia ramosa are used by the Khasi tribes of India, and the extracts were shown to effectively obliterate F. buski. Alpinia nigra, used by many tribals of north-east India for deworming
also caused significant efficacy.
control should be attempted.
F. buski is endemic in Asia
including China
, Taiwan
, South-East Asia, Indonesia
, Malaysia and India
. It has a prevalence of up to 60% in India
and mainland China
and has an estimated 10 million human infections. Infections occur most often in school-age children or in impoverished areas with a lack of proper sanitation systems.
A study revealed that F. buski was an endemic in central Thailand
, effecting approximately 2,936 people due to infected aquatic plants called water caltrop
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.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of trematodes. It consists only of two species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, F. buski and F. Magna, of which, F. buski, is more notable in terms of prevalence
Prevalence
In epidemiology, the prevalence of a health-related state in a statistical population is defined as the total number of cases of the risk factor in the population at a given time, or the total number of cases in the population, divided by the number of individuals in the population...
and pathogenicity
Pathogenicity
Pathogenicity is the ability of a pathogen to produce an infectious disease in an organism.It is often used interchangeably with the term "virulence", although virulence is used more specifically to describe the relative degree of damage done by a pathogen, or the degree of pathogenicity caused by...
as it causes the disease fasciolopsiasis
Fasciolopsiasis
Fasciolopsiasis results from an infection by the trematode Fasciolopsis buski, the largest intestinal fluke of humans .-Infection cycle:...
.
Fasciolopsis buski
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
, being the largest known parasitic fluke
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
in humans. The body can be up to 7.5 cm in length and 2.5 cm in width. It is a common parasite of humans and pigs
PIGS
PIGS is a four letter acronym that can stand for:* PIGS , Phosphatidylinositol glycan anchor biosynthesis, class S, a human gene* PIGS , the economies of Portugal, Italy , Greece and Spain...
and is most prevalent in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, mainly central
Central Asia
Central Asia is a core region of the Asian continent from the Caspian Sea in the west, China in the east, Afghanistan in the south, and Russia in the north...
and southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
. It belongs to the class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
Trematoda
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
, family
Family
In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...
Fasciolidae. The reason for its common name is due to the fact that it is one of the largest flukes
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
to infect humans. The worm
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
inhabits the upper region of the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
and, when abundant, can also be found in the lower areas of the intestine
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
and the stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
. Fasciolopsis buski is the cause of the disease fasciolopsiasis
Fasciolopsiasis
Fasciolopsiasis results from an infection by the trematode Fasciolopsis buski, the largest intestinal fluke of humans .-Infection cycle:...
.
In London, George Busk
George Busk
George Busk RN FRS was a British Naval surgeon, zoologist and palaeontologist.-Biography:Busk was born in St Petersburg, the son of the merchant Robert Busk and grandson of Sir Wadsworth Busk...
first described F. buski in 1843 after finding it in the duodenum
Duodenum
The duodenum is the first 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 anterior intestine or proximal intestine may be used instead of duodenum...
of a sailor. In 1925, Barlow first determined its life cycle in humans
Morphology
F. buski is a large leaf-shaped, dorso-ventrally flattened wormWorm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
that is characterized by a blunt anterior end, undulating, unbranched ceca
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
(sac-like cavity with a single opening), tandem, dendritic testes, branched ovaries, and ventral suckers
Sucker (parasitic worms anatomy)
The sucker is an attachment organ of parasitic worms.-In Platyhelminths:In Platyhelminths , the sucker is called bothridium....
to attach itself to the host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
. The acetabulum
Acetabulum
The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...
is larger than the oral sucker
Sucker (parasitic worms anatomy)
The sucker is an attachment organ of parasitic worms.-In Platyhelminths:In Platyhelminths , the sucker is called bothridium....
. It has extensive vitelline
Vitelline
Vitelline can refer to:* Vitelline duct* Vitelline veins* Vitelline membrane...
follicles. It can be distinguished from other fasciolids by a lack of cephalic cone or "shoulders" and the unbranched ceca
Cecum
The cecum or caecum is a pouch, connecting the ileum with the ascending colon of the large intestine. It is separated from the ileum by the ileocecal valve or Bauhin's valve, and is considered to be the beginning of the large intestine. It is also separated from the colon by the cecocolic...
.
Life Cycle
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
and stool
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
. In two weeks, eggs become embryonated in water, and after about seven weeks, eggs release tiny parasitic organisms called miracidia, which invade a suitable snail intermediate host. Several species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of genera
Genera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
Segmentina
Segmentina
Segmentina is a genus of small, air-breathing, freshwater snails, aquatic gastropod mollusks or micromollusks in the family Planorbidae, the ramshorn snails....
and Hippeutis
Hippeutis
Hippeutis is a genus of minute air-breathing freshwater snails, aquatic pulmonate gastropod mollusks or micromollusks in the family Planorbidae, the ramshorn snails.Albrecht et al...
serve as intermediate hosts. In the snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
the parasite undergoes several developmental stages (sporocysts, rediae, and cercariae). The cercariae are released from the snail and encyst as metacercariae on aquatic plants such as water chestnut
Eleocharis dulcis
The Chinese water chestnut , more often called simply the water chestnut, is a grass-like sedge grown for its edible corms. The water chestnut is actually not a nut at all, but an aquatic vegetable that grows in marshes, underwater in the mud...
, water caltrop
Water caltrop
The water caltrop, water chestnut, buffalo nut, bat nut, devil pod or Singhara or Pani-fol is either of two species of the genus Trapa: Trapa natans and Trapa bicornis...
, lotus, bamboo
Bamboo
Bamboo is a group of perennial evergreens in the true grass family Poaceae, subfamily Bambusoideae, tribe Bambuseae. Giant bamboos are the largest members of the grass family....
, and other edible plants. The mammalian host, or the final host, becomes infected by ingesting metacercariae on the aquatic plants. After ingestion, the metacercariae excyst in the duodenum
Duodenum
The duodenum is the first 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 anterior intestine or proximal intestine may be used instead of duodenum...
in about three months and attach to the intestinal wall
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
. There they develop into adult flukes
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
(20 to 75 mm by 8 to 20 mm) in approximately 3 months, attached to the intestinal wall
Intestine
In human anatomy, the intestine is the segment of the alimentary canal extending from the pyloric sphincter of the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine...
of the mammalian hosts (humans and pigs
PIGS
PIGS is a four letter acronym that can stand for:* PIGS , Phosphatidylinositol glycan anchor biosynthesis, class S, a human gene* PIGS , the economies of Portugal, Italy , Greece and Spain...
). The adults have a life span
Life span
Life span or lifespan may refer to:*Maximum life span, the maximum lifespan observed in a group*Life expectancy, the average lifespan expected of a group*Longevity, the average lifespan expected under ideal conditions...
of about one year.
Symptoms
Most infections are light and asymptomaticAsymptomatic
In medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical...
. In heavy infections, symptoms can include abdominal pain
Abdominal pain
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
, chronic
Chronic
Chronic may refer to:* Chronic , a disease that is long-lasting and reoccurring.* Chronic toxicity, a substance with toxic effects after continuous or repeated exposure* The Chronic, a 1992 album by Dr. Dre...
diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, ascites
Ascites
Ascites is a gastroenterological term for an accumulation of fluid in the peritoneal cavity.The medical condition is also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy. Although most commonly due to cirrhosis and severe liver...
, toxemia
Toxemia
Toxemia may refer to:* A generic term for the presence of toxins in the blood, see Bacteremia* An outdated medical term for Pre-eclampsia...
, allergic responses
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
, sensitization caused by the absorption of the worms allergenic metabolites (may eventually cause death of patient), and intestinal obstruction.
Laboratory Diagnosis
Microscopic identification of eggs, or more rarely of the adult flukesTrematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
, in the stool
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
or vomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of Fasciola hepatica
Fasciola hepatica
Fasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects the livers of various mammals, including humans. The disease caused by the fluke is called fascioliasis . F...
.
Treatment
PraziquantelPraziquantel
Praziquantel is an anthelmintic effective against flatworms. Praziquantel is not licensed for use in humans in the UK; it is, however, available as a veterinary anthelmintic, and is available for use in humans on a named-patient basis....
is the drug
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
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
Tetrachloroethylene, also known under its systematic name tetrachloroethene and many other names, is a chlorocarbon with the formula Cl2C=CCl2. It is a colourless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid." It has a sweet odor detectable by...
as capable of reducing faecal egg counts by up to 99%. Other anthelmintics that can be used include thiabendazole
Thiabendazole
Tiabendazole is a fungicide and parasiticide.-Fungicide:...
, mebendazole
Mebendazole
Mebendazole or MBZ is a benzimidazole drug developed by Janssen Pharmaceutica and marketed as Vermox, Ovex, Antiox, and Pripsen...
, levamisole
Levamisole
Levamisole is an anthelminthic and immunomodulator belonging to a class of synthetic imidazothiazole derivatives. It was discovered at Janssen Pharmaceutica in 1966...
and pyrantel pamoate
Pyrantel pamoate
Pyrantel pamoate or Pyrantel Embonate , is used as a deworming agent in the treatment of hookworms and roundworms in domesticated animals such as horses, cattle, sheep, pigs, cats, dogs, and many other species. It is a combination of pyrantel and pamoic acid...
. oxyclozanide
Oxyclozanide
Oxyclozanide is a salicylanilide anthelmintic. It is used in the treatment and control of Fascioliasis in ruminants mainly domestic animals like Cattle, Sheep and Goats. It mainly acts by uncoupling of Oxidative phosphorylation in flukes....
, hexachlorophene
Hexachlorophene
Hexachlorophene, also known as Nabac, is a disinfectant. The compound occurs as a white to light-tan crystalline powder, which either is odorless or produces a slightly phenolic odor. In medicine, hexachlorophene is very useful as a topical anti-infective, anti-bacterial agent, often used in soaps...
and nitroxynil are also highly effective.
Natural Cure
Black walnut green hull is proven effective against this trematode on his adult phase, for the larvae wormwoodArtemisia absinthium
Artemisia absinthium is a species of wormwood, native to temperate regions of Eurasia and northern Africa....
is known to help, and for the eggs cloves are used. Flemingia vestita and Lysimachia ramosa are used by the Khasi tribes of India, and the extracts were shown to effectively obliterate F. buski. Alpinia nigra, used by many tribals of north-east India for deworming
Deworming
Deworming is the giving of an anthelmintic drug to an animal to rid it of intestinal parasites, such as roundworm and tapeworm...
also caused significant efficacy.
Prevention
Prevention can be easily achieved by immersion of vegetables in boiling water for a few seconds to kill the infective metacercariae, avoiding the use of nightsoil as a fertilizer, and maintenance of proper sanitation and good hygiene. Additionally, snailSnail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
control should be attempted.
Epidemiology
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
including China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, South-East Asia, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
, Malaysia and India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. It has a prevalence of up to 60% in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and mainland China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and has an estimated 10 million human infections. Infections occur most often in school-age children or in impoverished areas with a lack of proper sanitation systems.
A study revealed that F. buski was an endemic in central Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, effecting approximately 2,936 people due to infected aquatic plants called water caltrop
Water caltrop
The water caltrop, water chestnut, buffalo nut, bat nut, devil pod or Singhara or Pani-fol is either of two species of the genus Trapa: Trapa natans and Trapa bicornis...
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
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
such as Ayuthaya Province. The high incidence of infection was prevalent in females and children ages 10–14 years of age.