Background
Dipylidiasis is a common tapeworm infection of dogs and cats caused by Dipylidium caninum. Linnaeus first described dipylidiasis in humans in 1758.
Dipylidiasis has a worldwide distribution. Humans become infected by accidental ingestion of dog or cat fleas that contain D caninum cysticercoids (larva). The risk for infection to humans is low.
Pathophysiology
Dipylidiasis in humans occurs through accidental ingestion of the dog or cat flea or the dog louse infected with cysticercoids (the larval form of D caninum). These fleas and lice are the intermediate host for D caninum.
Cysticercoids develop into adult worms in the small intestine of the host in about 20 days. The adult worm may attain a length of 10-70 cm and is 2-3 mm in diameter. The worms have a lifespan of less than 1 year.
Pathological changes due to dipylidiasis have not been described.
Epidemiology
Frequency
United States
A few cases of dipylidiasis have been reported in the United States, but the exact incidence is not known.
International
Dipylidiasis is distributed worldwide, and human infection has been reported in Africa, Argentina, Australia, Chile, China, Europe, Guatemala, India, Japan, and the Philippines. [1, 2]
Race
Dipylidiasis does not appear to have a racial predilection.
Sex
Males and females are equally susceptible to dipylidiasis.
Age
Dipylidiasis is most common in infants and in children younger than 8 years. Dipylidiasis has been reported in a 5-week-old infant. [3]
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Adult tapeworm of Dipylidium caninum. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Proglottid of Dipylidium caninum. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Dipylidium caninum proglottid under a dissecting microscope cleared with lactophenol. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Proglottid of Dipylidium caninum stained with carmine. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Egg packets of Dipylidium caninum. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Egg packets of Dipylidium caninum. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Egg of Dipylidium caninum. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Life cycle of Dipylidium caninum. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
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Dipylidium caninum egg packet that contains 8 visible eggs, in a wet mount. Image provided courtesy of the Centers for Disease Control and Prevention (CDC).
