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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
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,
What is the intermediate hose in Taenia solium?
4) fish Which is not a disease of tapeworms?
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
What are three ways to diagnose tapeworm infestation?
fecal examination True or False : Tapeworm infestation can be an
example of commencalism.
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