Dwarf tapeworm

Dwarf tapeworm
	Dwarf tapeworm ( Hymenolepis nana )
Systematics
Class :	Tapeworms (Cestoda)
Subclass :	True tapeworms (Eucestoda)
Order :	Cyclophyllidea
Family :	Hymenolepididae
Genre :	Hymenolepis
Type :	Dwarf tapeworm
Scientific name
	Hymenolepis nana
	( Carl von Siebold , 1852)

The dwarf tapeworm ( Hymenolepis nana , Syn .: Rodentolepis nana , Taenia nana ) is a parasite belonging to the tapeworms (Cestoda) that attacks humans and other primates and rodents as the ultimate host . The dwarf tapeworm has a specialty among tapeworms in that it does not need an intermediate host , i.e. a direct transition from humans to rodents and vice versa is possible. Optional intermediate hosts are various beetle species classified as storage pests such as meal beetles .

distribution

The dwarf tapeworm is distributed worldwide, but is rare in Central Europe. A particular frequency of infestation can be observed in children.

features

The worm can reach a length of one to four centimeters, in rare cases up to six centimeters, and a width of a maximum of two millimeters. Otherwise, it has all the characteristics of tapeworms: it has a ring of hooks and four suction cups on the head ( scolex ) and not pronounced proglottids . The wreath of hooks is the distinguishing feature of the rat tapeworm Hymenolepis diminuta .

The eggs are round to oval, about 50 µm in size and are surrounded by a thin, smooth shell. Inside is the oncosphere , reinforced with 6 hooks , which is surrounded by a thin membrane with thickenings and filaments at the poles.

Life cycle

There are two ways of distribution. In the first, the eggs are ingested by flour beetles ; A cysticercoid develops in these , which remains in the beetle and encapsulates itself. If infected grain is consumed by humans or rats, the cysticercoid is dissolved and the adult worms settle in the duodenum . The second and more common way of spreading, however, is auto-infection, in which the eggs are ingested directly by an infected host.

Harmful effect

The symptoms depend on the intensity (with this type of tapeworm, direct reproduction in the intestine is also possible) and the duration of the infestation. Initially - in the first year - the infection is usually symptom-free. Since the dwarf tapeworm damages the inner surface of the intestine, extensive necroses can later develop . He also releases metabolites that are potentially toxic for the innkeeper from his body . The result can be B. Various allergies, but also disorders of the digestion of proteins . External signs include headache, paleness, and feelings of tiredness. Upset stomach, gas, diarrhea and severe abdominal pain are also common, regardless of the food ingested. These symptoms are more pronounced in malnourished and immunocompromised people. A disease that goes on for years also causes a marked weight loss, especially because this parasite - like other tapeworm species - consumes a lot of nutrients from the chyme in large populations .

Prevention and treatment

Infestation with tapeworms can be combined with hygienic measures and prevent contact from anus to mouth prevention .

Infectious diseases caused by the dwarf tapeworm can be treated with an oral dose of praziquantel .

literature

Johannes Dönges: Parasitology. With special consideration of human pathogenic forms. 2nd Edition. Thieme, Stuttgart 1988, ISBN 3-13-579902-6 .
Heinz Mehlhorn, Gerhard Piekarski: Outline of parasite science. 6th edition. Spectrum, Heidelberg 2002, ISBN 3-8274-1158-0 .
Richard Lucius, Brigitte Loos-Frank: Biology of Parasites. 2nd edition - Springer-Verlag, Berlin / Heidelberg 2008, ISBN 978-3-540-37707-8 .

Web links

Helminths - Cestoda. In: Dr Sadjjadi's Online Atlas of Parasitology. (Microscope images)

Individual evidence

↑ ^a ^b M. Müller et al .: Mass infestation with the dwarf tapeworm Hymenolepis nana in chinchilla. In: Parasiten Spezial 1/2010 (publisher supplement to Tierärztliche Umschau Kleintiermedizin), pp. 17–20.
↑ Parasitic Deseases. ( Memento from June 16, 2010 in the Internet Archive ) In: Hamster Diseases. (English).
^ Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 292.

[Müller-1] M. Müller et al .: Mass infestation with the dwarf tapeworm Hymenolepis nana in chinchilla. In: Parasiten Spezial 1/2010 (publisher supplement to Tierärztliche Umschau Kleintiermedizin), pp. 17–20.

[2] Parasitic Deseases. ( Memento from June 16, 2010 in the Internet Archive ) In: Hamster Diseases. (English).

[3] Marianne Abele-Horn: Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , p. 292.