Microbiology & parasitology

Parasites-gastrointestinal (not liver)

Dipylidium caninum



Topic Completed: 1 January 2015

Minor changes: 18 June 2021

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PubMed Search: Dipylidium caninum[TI]

Haind Fadel, M.D.
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Cite this page: Fadel H. Dipylidium caninum. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/parasitologydipylidiumcaninum.html. Accessed October 15th, 2021.
Definition / general
  • Common tapeworm of dogs and cats in most parts of the world which may infect humans, especially children
  • Human infections have been reported in Europe, the Philippines, China, Japan, Argentina and United States
Diagrams / tables

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Life cycle

Life cycle
  • Usually tapeworm eggs are ingested by flea larvae, which infest areas frequented by dogs or cats
  • Cysticercoid larvae persist as the flea undergoes metamorphosis to the adult stage
  • Dogs, cats and humans ingest the adult flea containing the infectious cysticercoid
  • Children are at highest risk for infection because of their close contact with pets
  • Worms mature in the human small intestine and grow up to 70 cm in length
  • Infection produces few symptoms
Clinical features
  • Most infections are asymptomatic but mild gastrointestinal disturbances may occur
  • Most striking feature in animals and children consists of the passage of proglottids, found in the perianal region, in feces, on diapers and occasionally on floor coverings and furniture
  • Proglottids are motile when freshly passed and may be mistaken for maggots or fly larvae
  • Pets may exhibit behavior to relieve anal pruritis, such as scraping anal region across grass or carpeting
Diagnosis
  • Based on finding characteristic eggs, egg packets or proglottids in feces
  • Spherical eggs contain a six hooked embryo, measure from 24 - 40 μm in diameter and occur singly or in packets
  • Scolex (head) is somewhat elongated with four suckers and a small retractable rostellum
  • Proglottids are barrel shaped and possess two genital pores, one on each lateral margin, which give rise to the common name double pored tapeworm
Case reports
Treatment
  • Infection is self limiting in humans and typically clears spontaneously in 6 weeks
  • Praziquantel:
    • Adults, 5 - 10 mg/kg orally in a single dose
    • Not approved for children less than 4 years old but has been used successfully in children as young as 6 months
  • Niclosamide is effective but unavailable in United States
  • No purge or follow up stool examination is indicated but appearance of proglottids after therapy is indication for retreatment
Gross description
  • Dipylidium caninum adults measure 10 - 70 cm long
  • As proglottids mature, they break off from the parent stroblia
Gross images

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Adult tapeworm

Microscopic (histologic) images

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Eggs, various images

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Proglottids

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Cross sections

Differential diagnosis
  • Other intestinal tapeworms
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