Microbiology, parasitology & COVID-19

Parasites-gastrointestinal (not liver)

Taenia saginata



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Last staff update: 12 August 2022

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PubMed Search: Taenia saginata[TI] cestodes full text[sb]

Haind Fadel, M.D.
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Cite this page: Fadel H. Taenia saginata. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/parasitologytaeniasaginata.html. Accessed February 7th, 2023.
Definition / general
  • "Beef tapeworm"
  • Tapeworm infections have been reported since 1500 B.C. and recognized as one of the earliest human parasites
  • Taenia saginata was differentiated from T. solium infection by the late 1700s
  • However, the exact life cycle of T. saginata was not discovered until 1863, when cattle was identified as the immediate host
Epidemiology
  • Especially common in Middle East, Africa, Europe, Asia, Latin America
Pathophysiology
  • Humans are the sole definitive host
  • When humans ingest infected raw or incompletely cooked beef, the cysticercus develops into a reproductive adult in the small intestine in 2 - 3 months
  • Symptoms are rare but may include abdominal discomfort and diarrhea
  • Unlike T. solium, the eggs of T. saginata are not infectious to humans and their ingestion does not result in cysticercosis
Diagrams / tables

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Life cycle

Clinical features
  • For humans in good health, there are few serious symptoms associated with tapeworm infection
  • For both T. saginata and T. solium, patients may have diarrhea, constipation, flatulence, hunger pain, weight loss; rarely appendicitis
  • Most common complaint is embarrassment and discomfort when proglottids crawl out of anus
  • Taeniasis infection may compromise the immune system; especially in young children, this may have a profound effect on their health
Incubation period
  • Takes 5 to 12 weeks for worm to mature into adulthood in the human intestine
  • Usually only a single worm is present at one time, although multiple worms have been reported
Diagnosis
  • Diagnosis is made by finding eggs in stool, using direct or concentration techniques or in the perianal folds, using the cellophane tape technique
  • Eggs are spherical and measure 31 - 43 μm in diameter
Case reports
Treatment
  • Both T. saginata and T. solium are treated with oral medication, usually a single dose of niclosamide
  • Therapy is usually very successful and most cases are completely eradicated
  • If proglottids reappear, retreatment is administered
Microscopic (histologic) description
  • Proglottids of taeniids have a characteristic lateral protrusion known as the genital pore
  • Careful injection of India ink through the genital pore, using a tuberculin needle and syringe, may succeed in outlining the uterus
  • Gravid uterus of T. saginata has 15 - 20 lateral branches, compared to 7 - 13 for T. solium
  • Proglottids may also be cleared overnight in glycerol or stained with carmine or hematoxylin using published procedures
  • If recovered, the scolex of T. saginata can be identified by the presence of four suckers and the absence of hooks on the crown or rostellum
  • Shell is thick, radially striated and contains a six hooked embryo
  • Eggs of all Taenia species are indistinguishable and should be reported only as Taenia eggs
Microscopic (histologic) images

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Gravid uterus of T. saginata with > 13 lateral branches

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