Taenia: Beef vs. Pork Tapeworm

• Platyhelminthes are flatworms, including Cestodes like Taenia saginata and Taenia solium.

Taenia Saginata (Beef Tapeworm)

• The beef tapeworm's definitive host is humans harboring the adult form.
• Intermediate hosts are cattle, which carry the larval stage.
• Humans get it by eating raw/undercooked beef.
• Humans experience intestinal symptoms.
• The adult form of the tapeworm lives in the small intestine of humans, especially the jejunum.
• The scolex has four oral suckers and no rostellum or hooklets.
• This species features a longer neck.
• There are 1,000–2,000 proglottids (segments).
• The uterus has more than 13 branches.
• Two ovaries are present, without an accessory lobe.
• The worms grow up to 5 meters.

Taenia Solium (Pork Tapeworm)

• The pork tapeworm's definitive host is humans harboring the adult form.
• Intermediate hosts are pigs, which carry the larval stage.
• Humans can be accidental intermediate hosts, leading to cysticercosis.
• Humans get it by eating raw/undercooked pork.
• Humans experience intestinal and neurological symptoms.
• The adult form resides in the human small intestine.
• Its scolex has four suckers, with a rostellum and two rows of hooklets.
• The neck is shorter in length.
• There are 800–2,000 proglottids (segments).
• It has 12 major uterine branches.
• The species has two ovaries with an accessory lobe.
• Worms grow 2–7 meters in length.

Taenia Species Life Cycle

• The two species have a similar life cycle, differing only in the intermediate host.
• Eggs or gravid proglottids pass through human feces and can survive in the environment for days to months.
• Cattle (for T. saginata) or pigs (for T. solium) ingest contaminated vegetation.
• In the animal intestine, oncospheres hatch, penetrate the intestinal wall, and migrate to striated muscles, where they develop into cysticerci (larvae).
• Humans get infected by eating raw or undercooked infected meat.
• In the human intestine, the cysticercus develops into an adult tapeworm in ~2 months and can survive for years.
• The adult tapeworm attaches to the small intestine and produces gravid proglottids, which detach and are excreted in feces, continuing the cycle.

Taenia solium and Cysticercosis

• Cysticercosis occurs when humans accidentally ingest Taenia solium eggs.
• Intestinal taeniasis is caused by ingesting larvae.
• Cysticercosis occurs from contaminated food, water, or by fecal-oral transmission from an infected person.
• Eggs are immediately infectious, without an external development period.
• Once ingested, oncospheres hatch, penetrate the intestinal wall, and enter the bloodstream.
• They migrate to various tissues, including muscles, eyes, skin, and brain, where they form cysticerci (larvae).
• If cysticerci reach the central nervous system (CNS), they cause neurocysticercosis, which can lead to: seizures, headaches, hydrocephalus, neurological deficits.

Additional Information

• The parasite exists in three stages: adult worm, larvae, and eggs.
• The larval stage is infectious to humans and eggs are infectious to cattle.
• Both species cause intestinal taeniasis, with symptoms like abdominal discomfort, indigestion, nausea, diarrhea, and weight loss.
• T. solium larvae can invade different tissues and cause severe complications, including neurocysticercosis if they reach the brain.
• Praziquantel is used for treatment.
• Diagnosis is achieved by observing eggs or gravid proglottids in the stool.