Hymenolepididae

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Hymenolepididae
H nana adultF.JPG
Three adult Hymenolepis nana
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Family: Hymenolepididae
Genera

Many, see text

The Hymenolepididae are family of cyclophyllid tapeworms. Their characteristic feature is the small number of testes (one to four). The unilateral genital pores and large external seminal vesicle allow for easy recognition. Most species are small, transparent, and easy to study. The family contains over 90 genera with over 900 species, having as their definitive host birds (c. 700 species) or mammals (about 250 species). Most reside in the intestines of their definitive hosts. The majority of species with known lifecycles have arthropods as intermediate hosts. [1]

Contents

As human parasites

The family Hymenolepididae has only two species which infects humans: the disease hymenolepiasis is caused by Hymenolepis nana and H. diminuta , which are sometimes classified in the genus Rodentolepis.

Most cases of hymenolepiasis are caused by H. nana. It occurs worldwide, but in temperate climates, children and people living in institutions are more likely to be infected. A morphologically-identical variety of H. nana, H. nana var. fraterna infects rodents, but the human strain of H. nana is essentially non-infective to rodents. [2] Unlike most tapeworms, including H. diminuta, H. nana can complete its lifecycle without an intermediate host. [3] Pathological effects of infection are rare and occur in massive infections through autoinfection, where the parasite is able to complete its lifecycle within the intestine of the human host, without passing through an intermediate host outside the body. With increasing worm burden, symptoms such as restlessness, irritability, diarrhea, and abdominal pain occur. [4]

H. diminuta is primarily a parasite of rats, but human infections occur as incidental hosts. It is a larger species than H. nana and lacks hooks on the rostellum; it has three testes per proglottid. Species from a diverse set of arthropod taxa, including earwigs, butterflies, and beetles, can be intermediate hosts for this species, which is unusual for a tapeworm. [5] Grain beetles are common intermediate hosts, because they live in piles of grain where they can be ingested by rats, which are the definitive hosts. [6]

Drugs commonly used for treatment of hymenolepiasis are praziquantel, niclosamide, and paromomycin.

Selected genera

Related Research Articles

<i>Diphyllobothrium</i> Genus of flatworms

Diphyllobothrium is a genus of tapeworms which can cause diphyllobothriasis in humans through consumption of raw or undercooked fish. The principal species causing diphyllobothriasis is D. latum, known as the broad or fish tapeworm, or broad fish tapeworm. D. latum is a pseudophyllid cestode that infects fish and mammals. D. latum is native to Scandinavia, western Russia, and the Baltics, though it is now also present in North America, especially the Pacific Northwest. In Far East Russia, D. klebanovskii, having Pacific salmon as its second intermediate host, was identified.

Hymenolepiasis is infestation by one of two species of tapeworm: Hymenolepis nana or H. diminuta. Alternative names are dwarf tapeworm infection and rat tapeworm infection. The disease is a type of helminthiasis which is classified as a neglected tropical disease.

<i>Taenia</i> (flatworm) Genus of flatworms

Taenia is the type genus of the Taeniidae family of tapeworms. It includes some important parasites of livestock. Members of the genus are responsible for taeniasis and cysticercosis in humans, which are types of helminthiasis belonging to the group of neglected tropical diseases. More than 100 species are recorded. They are morphologically characterized by a ribbon-like body composed of a series of segments called proglottids; hence the name Taenia. The anterior end of the body is the scolex. Some members of the genus Taenia have an armed scolex ; of the two major human parasites, Taenia saginata has an unarmed scolex, while Taenia solium has an armed scolex.

<i>Echinococcus granulosus</i> Species of flatworm

Echinococcus granulosus, also called the hydatid worm or dog tapeworm, is a cyclophyllid cestode that dwells in the small intestine of canids as an adult, but which has important intermediate hosts such as livestock and humans, where it causes cystic echinococcosis, also known as hydatid disease. The adult tapeworm ranges in length from 3 mm to 6 mm and has three proglottids ("segments") when intact—an immature proglottid, mature proglottid and a gravid proglottid. The average number of eggs per gravid proglottid is 823. Like all cyclophyllideans, E. granulosus has four suckers on its scolex ("head"), and E. granulosus also has a rostellum with hooks. Several strains of E. granulosus have been identified, and all but two are noted to be infective in humans.

<i>Echinococcus multilocularis</i> Species of flatworm

Echinococcus multilocularis, the fox tapeworm, is a small cyclophyllid tapeworm found extensively in the northern hemisphere. E. multilocularis, along with other members of the Echinococcus genus, produce diseases known as echinococcosis. Unlike E. granulosus,E. multilocularis produces many small cysts that spread throughout the internal organs of the infected animal. The resultant disease is called Alveolar echinococcosis, and is caused by ingesting the eggs of E. multilocularis.

<i>Dipylidium caninum</i> Species of flatworm

Dipylidium caninum, also called the flea tapeworm, double-pored tapeworm, or cucumber tapeworm is a cyclophyllid cestode that infects organisms afflicted with fleas and canine chewing lice, including dogs, cats, and sometimes human pet-owners, especially children.

<i>Hymenolepis nana</i> Species of flatworm

Dwarf tapeworm is a cosmopolitan species though most common in temperate zones, and is one of the most common cestodes infecting humans, especially children.

<i>Hymenolepis diminuta</i> Species of flatworm

Hymenolepis diminuta, also known as rat tapeworm, is a species of Hymenolepis tapeworm that causes hymenolepiasis. It has slightly bigger eggs and proglottids than H. nana and infects mammals using insects as intermediate hosts. The adult structure is 20 to 60 cm long and the mature proglottid is similar to that of H. nana, except it is larger.

<span class="mw-page-title-main">Eucestoda</span> Subclass of flatworms

Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda. Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Cestodaria. All tapeworms are endoparasites of vertebrates, living in the digestive tract or related ducts. Examples are the pork tapeworm with a human definitive host, and pigs as the secondary host, and Moniezia expansa, the definitive hosts of which are ruminants.

Diphyllobothriasis is the infection caused by tapeworms of the genus Diphyllobothrium.

<i>Hymenolepis</i> (flatworm) Genus of worms

Hymenolepis is a genus of cyclophyllid tapeworms that cause hymenolepiasis. They parasitise mammals, including humans. Some notable species are:

<span class="mw-page-title-main">Cestoda</span> Class of flatworms

Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, known as tapeworms. Their bodies consist of many similar units known as proglottids—essentially packages of eggs which are regularly shed into the environment to infect other organisms. Species of the other subclass, Cestodaria, are mainly fish infecting parasites.

Diphyllobothrium mansonoides is a species of tapeworm (cestodes) that is endemic to North America. Infection with D. mansonoides in humans can result in sparganosis. Justus F. Mueller first reported this organism in 1935. D. mansonoides is similar to D. latum and Spirometra erinacei. When the organism was discovered, scientist did not know if D. mansonoides and S. erinacei were separate species. PCR analysis of the two worms has shown the two to be separate but closely related organisms.

Bertielliasis is the infection of Bertiella, a cestode tapeworm parasite that primarily infects nonhuman primates, rodents and Australian marsupials. Occasionally, human infections have been documented by one of two species: Bertiella studeri, or Bertiella mucronata. Of 29 different Bertiella species, only these two can infect humans.

<i>Raillietina</i> Genus of flatworms

Raillietina is a genus of tapeworms that includes helminth parasites of vertebrates, mostly of birds. The genus was named in 1920 in honour of a French veterinarian and helminthologist, Louis-Joseph Alcide Railliet. Of the 37 species recorded under the genus, Raillietina demerariensis, R. asiatica, and R. formsana are the only species reported from humans, while the rest are found in birds. R. echinobothrida, R. tetragona, and R. cesticillus are the most important species in terms of prevalence and pathogenicity among wild and domestic birds.

<i>Hymenolepis microstoma</i> Species of flatworm

Hymenolepis microstoma, also known as the rodent tapeworm, is an intestinal dwelling parasite. Adult worms live in the bile duct and small intestines of mice and rats, and larvae metamorphose in the haemocoel of beetles. It belongs to the genus Hymenolepis; tapeworms that cause hymenolepiasis. H. microstoma is prevalent in rodents worldwide, but rarely infects humans.

Taenia serialis, also known as a Canid tapeworm, is found within canines such as foxes and dogs. Adult T. serialis are parasites of carnivores, particularly dogs, with herbivorous lagomorph mammals such as rabbits and hares, serving as intermediate hosts. In definitive hosts, T. serialis is acquired by eating tissues from a variety of intermediate hosts. Accidental infection of humans though, can occur when eggs are ingested from food or water contaminated with dog feces and the human then becomes the T. serialis intermediate host.

<span class="mw-page-title-main">Rostellum (helminth)</span> Feature of tapeworm anatomy

Rostellum in helminthology is a protruding part of the anterior end of tapeworms. It is a retractable, cone-like muscular structure that is located on the apical end of the scolex, and in most species is armed with hooks, the organs of attachment to the host's intestinal wall. It is a parasitic adaptation in some cestodes for firm attachment in the gastrointestinal tract and is structurally different from one species to another, thereby becoming an important diagnostic feature.

Bertiella mucronata is a species of Bertiella, a type of cestode tapeworms known to cause Bertielliasis. It belongs to the genus Bertiella, family Anoplocephalidae. This is one of two species of Bertiella that can cause the condition in humans.

<i>Echinococcus vogeli</i> Species of flatworm

Echinococcus vogeli is a small cyclophyllid tapeworm found in Central and South America. E. vogeli, as well as other members of the genus Echinococcus, produce a disease called echinococcosis. Echinococcosis, also known has hydatidosis, is a result of ingesting the eggs of the genus Echinococcus. E. vogeli is similar to E. multilocularis in that both species produces many small cysts that spread throughout the internal organs of the infected animal. The ingestion of E. vogeli eggs, and the spreading of the cysts through infected host, will results in Polycystic Echinococcosis.

References

  1. Vasyl Tkach (1 June 2010). "Hymenolepididae". Planetary Biodiversity Inventory: A survey of tapeworms from vertebrate bowels of the Earth. Archived from the original on 5 September 2014. Retrieved 1 September 2014.
  2. Macnish, M.G.; Morgan, U.M.; Behnke, J.M.; Thompson, R.C.A. (2007). "Failure to infect laboratory rodent hosts with human isolates of Rodentolepis (Hymenolepis) nana". Journal of Helminthology (Submitted manuscript). 76 (1): 37–43. doi:10.1079/JOH200198. PMID   12018194. S2CID   11318170.
  3. "Examples of common cestodes". Schistosomiasis Research Group, Department of Pathology, University of Cambridge. 2010. Archived from the original on 2015-01-06. Retrieved 1 September 2014.
  4. "DPDx - Laboratory Identification of Parasitic Diseases of Public Health Concern - Hymenolepiasis". Centers for Disease Control and Prevention. 29 November 2013. Archived from the original on 4 September 2014. Retrieved 1 September 2014.
  5. Oldham, J.N. (1931). "On the Arthropod Intermediate Hosts of Hymenolepis diminuta (Rudolphi 1819)". Journal of Helminthology. 9 (1): 21–28. doi:10.1017/s0022149x00030212. S2CID   86132559.
  6. Stephen Dewey (2001). "Hymenolepis diminuta". Animal Diversity Web. Retrieved 1 September 2014.
  7. Tkach, V. V.; Velikanov, V. P. (1991). "Pseudhymenolepis turkestanica sp. n. (Cestoda: Hymenolepididae), a new cestode from shrews" (PDF). Annales de Parasitologie Humaine et Comparée. 66 (2): 54–56. doi: 10.1051/parasite/199166254 . ISSN   0003-4150. PMID   1952697. Open Access logo PLoS transparent.svg