Fasciolopsis

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Fasciolopsis
Scientific classification e
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Trematoda
Order: Echinostomida
Family: Fasciolidae
Genus: Fasciolopsis
Looss, 1899
Binomial name
Fasciolopsis buski
Morakote & Yano, 1990

Fasciolopsis (pronounced /ˌfæʃiɵˈlɒpsɨs/ US dict: făsh′·ē·ō·lŏp′·sĭs, or /fəˌʃaɪ.ɵˈlɒpsɨs/ US dict: fə·shī′·ō-) is a genus of trematodes. It consists only of two species, F. buski and F. Magna, of which, F. buski,[1] is more notable in terms of prevalence and pathogenicity as it causes the disease fasciolopsiasis.

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[edit] Fasciolopsis buski

Fasciolopsis buski egg

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.[2]

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

[edit] Morphology

F. buski is a large leaf-shaped, dorso-ventrally flattened worm 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.

[edit] Life Cycle

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.[3]

[edit] Symptoms

Most infections are light and asymptomatic. 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.[4]

[edit] Laboratory Diagnosis

Microscopic identification of eggs, or more rarely of the adult flukes, in the stool or vomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of Fasciola hepatica.

[edit] Treatment

Praziquantel 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.[5] oxyclozanide, hexachlorophene and nitroxynil are also highly effective.[6]

[edit] Natural Cure

Black walnut green hull is proven effective against this trematode on his adult phase, for the larvae wormwood 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.[7][8] Alpinia nigra, used by many tribals of north-east India for deworming also caused significant efficacy.[9]

[edit] 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, snail control should be attempted.

[edit] Epidemiology

Distribution of Fasciolopsis buski

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.[10]

A study revealed that F. buski was an endemic in central Thailand, effecting approximately 2,936 people due to infected aquatic plants called water caltrops 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.[11]

[edit] References

  1. ^ Wael M. Lotfy, Sara V. Brant,* Randy J. DeJong, Thanh Hoa Le, Aleksander Demiaszkiewicz, R. P. V. Jayanthe Rajapakse, Vijitha B. V. P. Perera, Jeff R. Laursen, and Eric S. Loker (2008). "Evolutionary Origins, Diversification, and Biogeography of Liver Flukes (Digenea, Fasciolidae)". The American journal of tropical medicine and hygiene (National Institutes of Health) 79 (2): 248–55. PMC 2577557. PMID 18689632. "Fasciolopsis buski is the next most basal member of the Fasciolidae. This species is one of two representatives of the Fasciolopsinae and is noteworthy for inhabiting the small intestine of suids and humans in Eastern Asia (Figure 3).". 
  2. ^ Roberts LS, Janovy, JJr (2009). "Foundations of Parasitology." McGraw Hill, New York, USA, pp. 272-273. ISBN 0073028274
  3. ^ Nakagawa K (1922). "The development of Fasciolopsis buski Lankester". J Parasitol 8 (4): 161–166. doi:10.2307/3271232. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1743&context=jrnlparasitology#page=27. 
  4. ^ Bhattacharjee HK, Yadav D, Bagga D. (2001). "Fasciolopsiasis presenting as intestinal perforation: a case report". Trop Gastroenterol 30 (1): 40–1. PMID 19624087. 
  5. ^ Rabbani GH, Gilman RH, Kabir I, Mondel G (1985). "The treatment of Fasciolopsis buski infection in children: a comparison of thiabendazole, mebendazole, levamisole, pyrantel pamoate, hexylresorcinol and tetrachloroethylene". Trans R Soc Trop Med Hyg 79 (4): 513–5. doi:10.1016/0035-9203(85)90081-1. PMID 4082261. 
  6. ^ Probert AJ, Sharma RK, Singh K, Saxena R. (1981). "The effect of five fasciolicides on malate dehydrogenase activity and mortality of Fasciola gigantica, Fasciolopsis buski and Paramphistomum explanatum". J Helminthol 55 (2): 115–22. doi:10.1017/S0022149X0002558X. PMID 7264272. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=5155408. 
  7. ^ Roy B, Tandon V. (1996). "Effect of root-tuber extract of Flemingia vestita , a leguminous plant, on Artyfechinostomum sufrartyfex and Fasciolopsis buski: a scanning electron microscopy study". Parasitol Res. 82 (3): 248–52. doi:10.1007/s004360050104. PMID 8801558. 
  8. ^ Challam M, Roy B, Tandon V. (2010). "Effect of Lysimachia ramosa (Primulaceae) on helminth parasites: motility, mortality and scanning electron microscopic observations on surface topography". Vet Parasitol. 169 (1–2): 214–8. doi:10.1016/j.vetpar.2009.12.024. PMID 20138704. 
  9. ^ Roy B, Dasgupta S, Tandon V. (2009). "Ultrastructural observations on Fasciolopsis buski and its alterations caused by shoot extract of Alpinia nigra". Microsc Res Tech. 72 (2): 61–6. doi:10.1002/jemt.20643. PMID 18924137. 
  10. ^ Keiser J, Utzinger J. (2009). "Food-borne trematodiases". Clin Microbiol Rev. 22 (3): 466–83. doi:10.1128/CMR.00012-09. PMC 2708390. PMID 19597009. 
  11. ^ Sadun EH, Maiphoom C (1953). "Studies on the epidemiology of the human intestinal fluke, Fasciolopsis Buski in Central Thailand". American Journal of Tropical Medicine and Hygiene 2 (6): 1070–84. PMID 13104816. 

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