Hymenolepididae
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Hymenolepis |
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. The family Hymenolepididae has only two species, Hymenolepsis nana and Hymenolepsis diminuta, which infects humans. Most species are small, transparent, and easy to study.
Species include:
- Hymenolepis nana is a cestode that commonly infects humans, especially school-aged children. It infects mammals like rodents and humans. However, it is unique 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. The 3 drugs that are used for treatment of hymenolepiasis are praziquantel, niclosamide, and paromomycin.[1]
There is some confusion regarding the host specificity. In a study published by Macnish MG et al. titled, Failure to infect laboratory rodent hosts with human isolates of Rodentolepis (Hymenolepis) nana, they tested their hypothesis that the human strain of R. nana is essentially non-infective to rodents.[2]
- Hymenolepis diminuta, is primarily a parasite of rats, but human infections occur. The human is an incidental host. It is a larger species and lacks hooks on the rostellum. It has unilateral genital pores and three testes per proglottid. It has been shown that more than 90 species of athropods can serve as suitable intermediate hosts, such as the stored-grain beetle.
[edit] References
- ^ Hymenolepiasis. emedicine. Retrieved on 2008-05-13.
- ^ Macnish MG, Morgan UM, Behnke JM, Thompson RCA (2007). "Failure to infect laboratory rodent hosts with human isolates of Rodentolepis (Hymenolepis) nana.". Journal of Helminthology. 76: 37-43.
