Dipylidium caninum
A. Classification
Phylum: Platyhelminthes
Class: Cestoda
Order: Cyclophyllidea
Family: Dipylidiidae
Genus/Species: Dipylidium caninum
Common names: Cucumber tapeworm
B. Morphology
The D. caninum is a relatively short tapeworm and the adult form is usually between 15 and
17 cm in length. It has a pumpkin-seed shape and tapers at each end. Mature proglottids (Figure 1.)
are longer than they are wide and contain two sets of each of the male and female reproductive
organs. A gravid proglottid (Figure 2.) usually measures 12 x 3mm and is filled with egg-capsules.
They are said to resemble rice grains or cucumber seeds (Figure 3.). The scolex (Figure 4.), has four
large suckers, a retractile rostellum, which is club-shaped with one to seven circlets of spines. The
egg is usually 35-40 microm, colorless, and is spherical, subspherical, or oval shaped. The eggs are
enclosed in a sac or capsule (Figure 6.) in groups of 5-30. The embryonated egg has 6 hooked
oncospheres inside the shell (Figure 7.). The larval form is roughly pear-shaped, looks like a typical
cysticercoid.
Figure 1. Mature proglottids of
D. caninum.
Figure 2. Gravid proglottids of
D. caninum.
Figure 3. This is the relative size of a gravid
proglottid that has been passed in comparison to
the size of a normal match. Note also the
resemblance to little pieces of rice grain here.
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Figure 4. Scolex, or hold-fast of the D. caninum. Only two
of the four suckers are shown in this 2-D image.
Figure 5. Sketches of the scolex and a mature proglottid of the D. caninum.
Figure 6. The capsule of eggs of
D. caninum.
Figure 7. A close up of egg/ oncosphere
developing inside the capsule. Note the hooks on the
oncosphere.
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C. Lifecycle and epidemiology
Dipylidium caninum usually infect cats and dogs but occasionally infect humans as well.
Feces is passed out of the infected host usually with an intact gravid proglottid. The proglottids
sometimes crawl out of the anus under their own power. After they have been passed egg capsules
are released. An intermediate host, the larval stage of a flea, ingests an egg which then releases an
oncosphere once it reaches the flea’s intestine. The oncosphere then penetrates the intestine and
stays in the body cavity where it develops into a cysticercoid larva. It matures in the body cavity
until it is an cysticercoid. During this time the flea also matures into an adult. The host is then
infected when it ingests the adult flea containing the cysticercoid. The dog is the usual host for
Dipylidium caninum but it can also infect cats, foxes, and humans. In the intestine of the host the
cysticercoid develops into and adult tape worm in about one month. The tape worm resides in the
small intestine where the scolex is attached. The proglottids that are produced have two genital
pores. As the proglottids move down the body they become mature, then gravid, and then detach
from the tapeworm and migrate to the anus and are passed in the. Children are the ones that tend to
be infected from playing with flea-infected animals.
Figure 8. Lifecycle of the D. caninum.
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D. Geographic distribution
The infection occurs worldwide and human infections have been reported in Europe, the
Philippines, China, Japan, Argentina, and the United States.
E. Pathology and Symptoms
Dipylidium caninum rarely occurs in humans. However, children seem to be more
susceptible than adults. A light infection with D. caninum tends to be asymptomatic in humans,
although a heavy infection may result in abdominal pain, diarrhea, irritability, and anal itching as
common symptoms. D. caninum is also asymptomatic in dogs and cats. Common symptoms in pets
seem to be similar to that of humans. D. caninum typically lives in the intestines for their entire
lives.
F. Diagnosis
A common technique of diagnosing D. caninum is to observe the eggs in fecal
smears. However, the eggs are rarely released into the feces. Therefore, it is easier to diagnose D.
caninum by observing cucumber seed shaped proglottids in the feces. If proglottids are viewed under
the microscope, two sets of reproductive systems may be visible. Gravid proglottids contain
transparent capsules with egg packets inside.
Figure 10. Proglottids in
cat feces. They are the
cream colored objects
on the surface of the
feces sample.
<http://cal.vet.upenn.edu/dxendopar/parasitepages/cestodes/d_caninum.html>
G. Treatment
A common treatment of D. caninum is praziquantel. The recommended dosage for humans
is 3 to 5 mg of praziquantel per one kg body weight. Praziquantel works by adjusting the cell
membrane permeability of the worm, which leads to a disintegration of the worm’s tegument.
Another common treatment of D. caninum is Epsiprantel. It is unknown how epsiprantel works.
However, it is suspected that epsiprantel may interfere with calcium metabolism leading to the
detachment and disruption of the tegument. The recommended dosage for dogs is 5.5 mg per kg of
body weight and the recommended dosage for cats is 2.75 mg per kg of body weight. However, the
cats and dogs must be over seven weeks old.
H. Public Health and Eradication
There are three primary prevention and control measures, and if adhered to strictly would
eradicate human infections of D. caninum. The first would be to have dogs and cats seen by a
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veterinarian on a regular basis for routine procedures like deworming and administration of antihelminth medications. The second measure would be to regularly treat dogs and cats for fleas.
Finally, and probably the hardest to control would be to teach children to not let dogs or cats lick
them near their mouths and to wash their hands after petting animals.
Works Cited
Ash, Orihel. Atlas of Human Parasitology. American Society of Clinical Pathologists. Chicago.
1997. pg. 38.
Center for Disease Control, 22 November 2004, “Dipylidium caninum,”
Parasites and Health,
<http://www.dpd.cdc.gov/DPDx/HTML/ImageLibrary/Dipylidium_il.htm>,
8 February 2005
College of Veterinary Medicine of Michigan State University, “Dipylidium caninum,”
<http://cvm.msu.edu/courses/mic569/docs/parasite/DCANINUM.HTML.>, 7 February 2005
Markell, John, Krotoski. Medical Parasitology. W.B. Saunders Co. 1999. Eighth edition. Pgs.
262-263.
Minnaganti, 22 October 2004, “Diplyidiasis” e-Medicine – Infectious Disease,
<http://www.emedicine.com/med/topic573.htm>, 8 February 2005
Nolan, 9 July 2004 “Dipylidium caninum Homepage,” Diagnosis of Veterinary Endoparasitic
Infections,
<http://cal.vet.upenn.edu/dxendopar/parasitepages/cestodes/d_caninum.html>,
8 February 2005
Stewart, 5 October 1998, “Dipylidium caninum (The Dog Tapeworm),” Helminthology and
General Parasitology Pages, <http://www.path.cam.ac.uk/~schisto/Tapes/Dipylidium.html>,
8 February 2005
The Ohio State University, “Dipylidium caninum (cucumber tapeworm),” Graphic Images of
Parasites, <http://www.biosci.ohio-state.edu/~parasite/dipylidium.html>, 8 February 2005
University of Michigan Museum Animal Diversity Web, “Dipylidium caninum,” .
<http://animaldiversity.ummz.umich.edu/site/accounts/information/Dipylidium
caninum.html>, 7 February 2005
University of Pennsylvania, “Dipylidium caninum Homepage,”
<http://cal.vet.upenn.edu/dxendopar/parasitepages/cestodes/d_caninum.html>, 7 February
2005.
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Univeristy of Texas, January 2002, “Map,”
<http://dev.lib.utexas.edu/maps/world_maps/world_pol02.jpg> 8 February 2005
Zeibig. Clinical Parasitology. W.B. Saunders Co. 1997. pgs. 190-192.
Carrie Graham
Carrie Barker
Drew Dickinson
Spring 2005
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