Hymenolepididae

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Hymenolepididae
H nana adultF.JPG
Three adult Hymenolepis nana
Scientific classification e
Kingdom: Animalia
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Family: Hymenolepididae
Genera

Many, see text

Hymenolepididae is family of cyclophyllid tapeworms. The characteristic feature is the small number of testes (one to four). The unilateral genital pores and large external seminal vesicle allows for easy recognition. Most species are small, transparent, and easy to study.

As human parasites[edit]

The family Hymenolepididae has only two species which infects humans: the disease hymenolepiasis is caused by Hymenolepis nana and H. diminuta which are sometimes placed in Rodentolepis. Hymenolepiasis occurs not too rarely in school-aged children. H. nana also infects other mammals, like rodents. It is unique[verification needed] among tapeworms in that an intermediate host is optional. Pathological effects of infection are rare and occur in massive infections through auto-infection. With increasing worm burden, symptoms such as restlessness, irritability, diarrhea, and abdominal pain. Humans become infected when they ingest infective eggs, through direct fecal-oral exposure. Diagnosis can be made by discovery of eggs in stool.

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. It has been shown that more than 90 species of arthropods are suitable intermediate hosts, such as the grain beetles[verification needed]. Drugs commonly used for treatment of hymenolepiasis are praziquantel, niclosamide, and paromomycin.

There is some confusion regarding the host specificity. It was found that the human strain of H. nana is essentially non-infective to rodents.[1]

Selected genera[edit]

References[edit]

  1. ^ 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 76(1): 37–43. doi:10.1079/JOH200198 PMID 12018194 (HTML abstract)