Dipylidium caninum, also known as the double-pored dog tapeworm or pumpkin seed tapeworm, is a common intestinal parasite of dogs and cats that can infect humans. It has a complex lifecycle involving fleas or lice as intermediate hosts. Adult worms are hermaphroditic tapeworms that can reach up to 70 cm in length. They reside in the small intestine and release proglottids containing eggs. Accidental ingestion of infected fleas can lead to mild gastrointestinal symptoms in humans, diagnosed by identifying proglottids or eggs in stool samples.

1. Dipylidium caninum
• Kingdom: Animalia
• Phylum: Platyhelminthes
• Class: Cestoda
• Order: Cyclophyllidea
• Family: Dipylidiidae
• Genus: Dipylidium
• Species: Dipylidium caninum

2. Dipylidium caninum
(Double-pored dog tapeworm,
pumpkin seed tapeworm)
• D. caninum is a common tapeworm of dog and cat
throughout the world.
• Human infections have been reported from
Europe, China, Japan and Argentina.
• Habitat: small intestines of man.

3. Morphology
• Adult worm measures 10-70 cm in length.
• Scolex is small, rhomboidal with transverse
diameter of 250-500 µm and has 4 deeply cupped,
oval suckers and median apical, club-shaped
retractile rostellum armed with 1-7 rows of
hooklets.
• Neck is short and slender.

5. • Strobila is consists of about of 200 proglottids,
mature and gravid proglottids are typically
pumpkin-seed-shaped.
• Eggs are spherical, thin, hyaline, brick-red tinged
shell, measuring 25-40 µm in diameter.

6. Life cycle
• Definitive host: canines, occasionally felines, and in
rare cases young children.
• Intermediate host: fleas (Ctenocephalides spp.) and
chewing lice.
• Eggs or proglottids are ingested by larval stage of
dog, cat or human flea, oncosphere are liberated in
intestine of these insects and migrate into their body
cavity where develop into cysticercoid larvae.
• The adult flea or louse will then harbour the infective
cysticercoid until a definitive host, such as a dog,
becomes infected by ingesting an infected flea or
louse while grooming themselves.

7. • Humans become infected by D. caninum by
accidentally ingesting an infected flea.
• In the small intestine of the definitive host, the
cysticercoid develops into an adult tapeworm, which
reaches maturity about one month after infection.
• Adult tapeworm produces proglottids, the proglottids
mature and become gravid and eventually detach
from the tapeworm and the lifecycle starts all over
again.

8. Life cycle

9. Pathogenesis and clinical signs
• Human infections are rare and normally restricted
to young children.
• Infection occurs from accidental ingestion of these
insect hosts while fondling cats and dogs.
• Symptoms are mild and consists of slight intestinal
disturbances including indigestion and loss of
appetite.

10. Diagnosis
• Infection is easily diagnosed by presence of
pumpkin-seed-shaped proglottids and 8-15
characteristic eggs can be seen microscopically.
• Treatment:
• Praziquantel and niclosamide