Causative agent: Tapeworms are parasitic Helmiths of the Phylum Platyhelminthes
(Flatworms) and Class
Cestodes. They include Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm)
and Diphyllobothrium
latum and Echinococcus granulosus .
Anatomy: Scolex (head) with suckers, sometimes hooks. Proglottids -body segments
continuously produced by
the scolex which contain both testes and ovaries that mature as they move away from
scolex to produce eggs.
Taenia tapeworms can live up to 25 yrs. and grow to 18 ft. D. latum have been found as
long as 32 ft. and can
produce millions of eggs per day. Tapeworms lack a digestive system but obtain food by
absorbing it through their
cuticle.
Diseases and Symptoms: Usually, none at all - in fact, infection might never be known.
Can cause blockage in
digestive tract, appendicitis. If the eggs hatch in a human, the larvae may cross the
intestinal lining and enter the
bloodstream, migrate to different organs in the body and develop into cysticerci (5 mm. -
8 in.). D. latum larvae that
infect people are called plerocercoids. Depending on location and number of cysticerci,
pathology can result. Ex:
Cysticerosis- (Taenia genus): eyes - blindness; spinal chord - paralysis; brain -
neurocysticerosis with similar
symptoms to brain tumor, causing traumatic neurological damage. Persons of Sandinavian
heritage are susceptible.
Diphyllobothriasis - (D. latum): Abdominal distention, flatulence, cramping, diarrhea and
sometimes anemia
(parasite has a high affinity for vitamin B12)
Hydatidosis -(E. granulosus): Instead of cysticerci, egg develops into a hyatid
cyst. Have been found large
enough to contain four gallons of fluid. Damage is due to cysts large size in vulnerable
areas (brain, bone) or rupture
of cysts, leading to development of many daughter cysts. Rupture may cause anaphylactic
shock. Infection is most
often seen in people who raise sheep or hunt/trap animals.
Diagnosis: Identification of eggs or proglottids in feces, immunologic tests, radiologic
tests (CAT, MRI) to diagnose
presence of cysticerci.
Prophylaxis: meat inspection, cooking meat thoroughly, treat non-pathogenic cases
theraputically to avoid spread of
disease, better personal hygiene, avoid use of human sewage as fertilizer.
Treatment: T. saginata, T. solium and D.latum - Niclosamide or Praziquantel; D. latum -
surgical removal of
hyatid cyst; E. granulosus - Albendazole.
Tapeworm T. saginata T. solium
D. latum E. granulosus
Definitive host human humans only
mostly humans, bears Dogs, coyotes
Internediate host mainly cattle humans and pigs fish
humans, deer,
sheep
Questions
What is the intermediate hose in Taenia solium?
1) dogs
2) cattle
3) pork
4) fish
Which is not a disease of tapeworms?
1) neurocysticerosis
2) anemia
3) hyatid cyst disease
4) severe weight loss/ excessive hunger
True or False : Ingesting the cysticercus of a tapeworm is more likely to cause disease
than ingesting tapeworm
eggs.
What are three ways to diagnose tapeworm infestation?
radiologic tests
immunologic tests
fecal examination
True or False : Tapeworm infestation can be an example of commencalism
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