Overview

Brief Summary

The trematode flatworm parasite Fasciolopsis buski is the largest intestinal fluke of humans. Fasciolopsis buski is found in Asia and the Indian subcontinent, especially in areas where humans raise pigs and consume freshwater plants.

Immature eggs are discharged into the intestine and stool. Eggs become embryonated in water and release miracidia, which invade a suitable snail intermediate host. In the snail, the parasites undergo several developmental stages: sporocyst, redia, and cercaria. The cercariae are released from the snail and encyst as metacercariae on aquatic plants. The mammalian hosts become infected by ingesting metacercariae on the aquatic plants. After ingestion, the metacercariae excyst in the duodenum 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. Mas-Coma et al. (2005) reviewed the biology, diagnosis, treatment, and epidemiology of fasciolopsiasis (Mas-Coma et al. 2005 and references therein).

(Centers for Disease Control Parasites and Health Website)

Fasciolopsis buski is one of the largest digenean trematode flatworms infecting humans. Pigs are the only important reservoir. Fasciolopsiasis (infection with Fasciolopsis) is present in many Asian countries. Fasciolopsis buski produces a large number of eggs in humans (13,000 to 26,000, mean 16,000/worm per day). Snail hosts are limited to small planorbids of the genera Segmentina, Hippeutis, and Gyraulus. Aquatic plants eaten by humans that may help transfer F. buski include water caltrop (Trapa natans in China, Trapa bispinosa in Taiwan, and Trapa bicornis in Bangladesh and Thailand), water chestnut (Eliocharis tuberosa), water hyacinth (Eichhornia spp.), water bamboo (Zizania spp.), water lotus (Nymphaea lotus), water lily (Nymphaea spp.), watercress (Nasturtium officinale), gankola (Otelia spp.), and water morning glory (Ipomoea aquatica). Metacercarial cysts on plants are visible to the naked eye. Up to 200 cysts may be found on the surface of one water caltrop, but the usual number is about 15 to 20. Cercariae may also encyst on the water surface. (Mas-Coma et al. 2005; Chai et al. 2009)

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Distribution

Geographic Range

Fasciolopsis buski is found mainly in Asia and the Indian subcontinent, occurring in Taiwan, Thailand, Laos, Bangladesh, India, and Vietnam. This trematode is especially prevalent in areas where pigs are raised, or where underwater vegetables such as water chestnut, water caltrop, lotus, and bamboo are often consumed. It has a prevalence of up to 60% in India and mainland China.

Biogeographic Regions: oriental (Native )

  • CDC. 2009. "DPDx - Fasciolopsis" (On-line). Laboratory Identification of Parasites of Public Health Concern. Accessed March 24, 2011 at http://www.dpd.cdc.gov/dpdx/HTML/Fasciolopsiasis.htm.
  • Le, T., V. Nguyen, B. Phan, D. Blair, D. McManus. 2004. Case report: unusual presentation of Fasciolopsis buski in a Viet Namese child. Transactions of the Royal Society of Tropical Medicine and Hygiene, 98/3: 193-194.
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Physical Description

Morphology

Physical Description

The eggs of Fasciolopsis buski vary in length from 130 to 150 micrometers and vary in width from 60 to 90 micrometers.

An adult Fasciolopsis buski is shaped like an elongated oval. The adult's length ranges from 20 mm to 75 mm, and has a width up to 20 mm, making it the largest human intestinal fluke. This species has poorly developed ventral and oral suckers, lacks "shoulders" present in other members of the family, and contains unbranched ceca. The adult is hermaphroditic.

Range length: 20 to 75 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

  • Liu, L., K. Harhasuta. 1996. Liver and intestinal flukes. Gastrenterology Clinics of North America, 25/3: 627-636.
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Ecology

Habitat

Fasciolopsis buski occurs in places with warm, moist, weather. This species is found in aquatic environments, where aquatic plants grow. Once consumed by the definitive host, the adult stage of Fasciolopsis buski adheres to the small intestine of its host, remaining until it dies or is removed.

Habitat Regions: temperate ; tropical ; freshwater

Aquatic Biomes: lakes and ponds; temporary pools

Wetlands: marsh ; swamp

Other Habitat Features: agricultural

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Trophic Strategy

Food Habits

Fasciolopsis buski is a parasite that resides and feeds in human and pig hosts. The adult stage is the only feeding stage, and it eats blood cells and mucus.

Animal Foods: mammals; body fluids

Primary Diet: carnivore (Sanguivore , Eats body fluids)

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Associations

Ecosystem Roles

Fasciolopsis buski is parasitic, using snails as an intermediate host to undergo development (this is fatal to the snail). This parasite reaches adulthood and produces eggs in mammal hosts, usually humans and pigs, but also equines, bovines, caprines, and ovines. Fasciolopsis buski can make its hosts very sick, and is very problematic in developing countries.

Fasciolopsis buski snail hosts that have been identified in Thailand include Segmentina hemisphaerula and Segmentina trochoideus. Plants identified to be important in transmission include water morning glory, Ipomoea aquatica; water caltrop Trapa bicornis; lotus, Nymphaea lotus; water cress, Neptunia oleracea; and water hyacinth, Eichhornia speciosa.

Ecosystem Impact: parasite

Species Used as Host:

Mutualist Species:

  • none

Commensal/Parasitic Species:

  • none

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Predation

There are no known predators to Fasciolopsis buski. It needs to be ingested by mammalian hosts in order to mature to its adult stage, and no information was found about predators in other stages of development.

Known Predators:

  • no known predators

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Life History and Behavior

Behavior

Communication and Perception

For a great part of its lifecycle, there is no communication or movement. Once leaving a snail host, Fasciolopsis buski encysts on aquatic vegetation until it is consumed by the definitive host.

However, perception is important in locating a snail host. When placed near susceptible snail hosts, the miracidia rapidly locate and penetrate the host, but the mechanism of recognition is unknown. Upon leaving the host, the cercariae swim freely before finding and encysting on aquatic plants.

Perception Channels: chemical

  • Graczyk, T., K. Alam, R. Gilman, G. Mondal, S. Ali. 2000. Development of Fasciolopsis buski (Trematoda: Fasciolidae) in Hippeutis umbilicalis and Segmentina trochoideus (Gastropoda: Pulmonata). Parasitology Research, 86/4: 324-326.
  • Nakagawa, K. 1922. The development of Fasciolopsis buski Lankester. The Journal of Parasitology, 8/4: 161-166. Accessed March 26, 2011 at http://www.jstor.org/stable/3271232?seq=1.
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Life Cycle

Development

The life cycle of Fasciolopsis buski begins when unembryonated eggs are released from the mammal host through the feces. An adult F. buski produces up to 26,000 eggs daily. To continue development, the eggs must reach fresh water. Once these eggs are released into water, they become embryonated and take up to 7 weeks to hatch at temperatures of 27 to 32 degrees Celsius.

The embryonated eggs release miracidia which invade snails and use them as an intermediate host. In the snail, the parasite undergoes several developmental stages, from miracidia to sporocyst to rediae to cercariae. The cercariae are released from the snail back into the aquatic environment. This is fatal to the snail host. The cercariae then encyst on aquatic plants (such as water chestnut, water caltrop, lotus, and bamboo) as metacercariae.

Mammalian hosts (humans and pigs) become infected when they ingest the plants that contain the parasite's metacercariae. Once ingested, the metacercariae excyst in the duodenum and attach to the intestinal wall. After 3 months, the parasites develop into adults and begin producing eggs.

Development - Life Cycle: metamorphosis ; diapause

  • Mas-Coma, S., M. Bargues, M. Valero. 2005. Fascioliasis and other plant-borne trematode zoonoses. International Journal for Parasitology, 35/11-12: 1255-1278.
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Life Expectancy

Lifespan/Longevity

The lifespan of the adult Fasciolopsis buski is one year. Factors that contribute to the lifespan and development of Fasciolopsis buski include being released into the proper environment for development (freshwater) and the ability to find an intermediate host. If this does not occur, Fasciolopsis buski will fail to develop and reach adulthood.

Average lifespan

Status: wild:
1 years.

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Reproduction

Fasciolopsis buski is hermaphroditic. Dendritic testes are in the posterior half of the worm, and branched ovaries are anterior to the testes. Fasciolopsis buski has extensive vitelline follicles, and a short uterus. Sexual reproduction occurs in the definitive mammal hosts (humans and pigs), and asexual reproduction occurs in the snail intermediate host.

There is no set time of the year that reproduction occurs. Once Fasciolopsis buski has matured in its definitive host, it produces eggs for the remainder of its life. Fasciolopsis buski can either self-fertilize or cross-fertilize.

Asexual reproduction and development occurs in snail hosts.

Breeding interval: Fasciolopsis buski breeds continuously, producing about 16,000 eggs per day.

Breeding season: Breeding occurs throughout the year.

Range number of offspring: 13000 to 26000.

Average number of offspring: 16000.

Average gestation period: 7 weeks.

Average age at sexual or reproductive maturity (female or asexual): 3 months.

Average age at sexual or reproductive maturity (male): 3 months.

Key Reproductive Features: iteroparous ; year-round breeding ; simultaneous hermaphrodite; sexual ; asexual ; fertilization (Internal ); oviparous

There is no parental investment with Fasciolopsis buski. Once eggs are produced, they are released from the host body with the feces, and develop by themselves.

  • CDC. 2009. "DPDx - Fasciolopsis" (On-line). Laboratory Identification of Parasites of Public Health Concern. Accessed March 24, 2011 at http://www.dpd.cdc.gov/dpdx/HTML/Fasciolopsiasis.htm.
  • Liu, L., K. Harhasuta. 1996. Liver and intestinal flukes. Gastrenterology Clinics of North America, 25/3: 627-636.
  • Mas-Coma, S., M. Bargues, M. Valero. 2005. Fascioliasis and other plant-borne trematode zoonoses. International Journal for Parasitology, 35/11-12: 1255-1278.
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Conservation

Conservation Status

There is no information about conservation efforts concerning Fasciolopsis buski, and Fasciolopsis buski does not seem to be in danger of disappearing.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

Fasciolopsis buski negatively impacts humans by causing disease, although most cases of this parasite are asymptomatic. Disease symptoms include ulceration, hemorrhage and abscess of the intestinal wall, diarrhea, and even death.

Negative Impacts: injures humans (causes disease in humans )

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Economic Importance for Humans: Positive

There was no information of any benefits that Fasciolopsis buski provides to humans. It is possible that further research may reveal ways that Fasciolopsis buski could be beneficial.

Positive Impacts: research and education

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Wikipedia

Fasciolopsis

This article is about the fluke. For the disease, see Fasciolopsiasis.

Fasciolopsis (/ˌfæʃiɵˈlɒpsɨs/[1] or /fəˌʃ.ɵˈlɒpsɨs/)[2] is a genus of trematodes. Just one species 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.

Fasciolopsis buski[edit]

General anatomy
Foreparts of a cleared, stained specimen of 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 of humans and pigs and is most prevalent in Southern and Southeastern Asia. It is a member of the family Fasciolidae in the order Echinostomida. The Echinostomida are members of the class Trematoda, the flukes. The fluke differs from most species that parasitise large mammals, in that they inhabit the gut rather than the liver as Fasciola species do. Fasciolopsis buski generally occupies the upper region of the small intestine, but in heavy infestations can also be found in the stomach and lower regions of the intestine. Fasciolopsis buski is the cause of the pathological condition fasciolopsiasis.[3]

In London, George Busk first described Fasciolopsis buski in 1843 after finding it in the duodenum of a sailor. After years of careful study and self experimentation, in 1925, Claude Heman Barlow determined its life cycle in humans.[4][5][6]

Morphology[edit]

Fasciolopsis buski is a large, leaf-shaped, dorsoventrally flattened fluke characterized by a blunt anterior end, undulating, unbranched ceca (sac-like cavities with single openings), tandem dendritic testes, branched ovaries, and ventral suckers to attach itself to the host. The acetabulum is larger than the oral sucker. The fluke has extensive vitelline follicles. It can be distinguished from other fasciolids by a lack of cephalic cone or "shoulders" and the unbranched ceca.

Life cycle[edit]

Fasciolopsis buski LifeCycle.gif

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.[7]

References[edit]

  1. ^ US dict: făsh′·ē·ō·lŏp′·sĭs
  2. ^ US dict: fə·shī′·ō-
  3. ^ Roberts LS, Janovy, J, Jr. (2009). "Foundations of Parasitology." McGraw Hill, New York, USA, pp. 272–273. ISBN 0-07-302827-4
  4. ^ Barlow, Claude Heman (1921). "Experimental Ingestion of the Ova of Fasciolopsis buski; Also the Ingestion of Adult Fasciolopsis buski for the Purpose of Artificial Infestation". The Journal of Parasitology 8 (1): 40–44. doi:10.2307/3270940. JSTOR 3270940. 
  5. ^ Dr. Claude Heman Barlow. Barlowgenealogy.com. Retrieved on 2012-12-18.
  6. ^ Barlow, Claude Heman (1925). "The Life Cycle of the Human Intestinal Fluke Fasciolopsis Buski (Lankester)". American Journal of Hygiene: 98. 
  7. ^ Nakagawa, K. (1922). "The development of Fasciolopsis buski Lankester". J Parasitol 8 (4): 161–166. doi:10.2307/3271232. 
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