Taenia Saginata - Beef Tapeworm
Taenia saginata is a large tapeworm that causes an infection called taeniasis. It is commonly known as
the beef tapeworm or cattle tapeworm because it uses cows as intermediate hosts. Humans are the only definitive
hosts. Taeniasis occurs worldwide and is relatively common in Africa, Eastern Europe, Latin America and the
The life cycle of Taenia saginata starts, when eggs are passed in the feces of an
infected human in a container called a proglottid or a tapeworm segment. They can survive a few months out in the
environment. If a cow (the intermediate host) feeds on contaminated vegetation, it ingests mature eggs or gravid
proglottids. In the small intestine larvae called oncospheres hatch, penetrate the intestinal wall, enter the
bloodstream and migrate to muscle tissue (rarely to liver or other organs), where they encyst into cysticerci. The
tiny cysticerci can survive for years and still be infective when humans eat the meat. If the beef is not cooked
properly, cysticerci excyst in the small intestine and develop into adults within two months. Adults attach to the
intestinal wall with their scolex using four suckers. The scolex has a pear-shaped and cup-like appearance reaching
1–2 mm in diameter. It is attached to the neck which starts to produce proglottids that make up the flat, long,
segmented body also known as strobila. The proglottids mature and grow bigger as they get further from the neck.
They are about 16–20 mm long and 5–7 mm wide and each proglottid has its own reproductive organs. They absorb
nutrients through their membranes and produce up to 100 000 eggs per day. Proglottids break off from the tail
and move with stool out of the human body. A full-grown Taenia saginata is whitish in colour and has about
1000–2000 proglottids and about six of them detach every day. The eggs usually stay inside the proglottids until
they are out in the environment. When the proglottid dries up, it ruptures and releases the eggs. The eggs are
embryonated, walnut brown and about 35 micrometers in diameter having a 6-hooked oncosphere inside its thick shell.
If the feces land on grazing ground for cattle, a cow might accidentally ingest proglottids or eggs. Taenia
saginata can live up to 25 years. It can grow up to 5 meters but in some cases can reach lengths of over 10
meters (coiled in the intestinal tract).
The disease is often asymptomatic. Taeniasis caused by Taenia saginata is more noticeable than
taeniasis caused by Taenia solium (although T.
solium is overall more dangerous because of the risk of cysticercosis). Heavy infection of Taenia
saginata can cause some of the following symptoms:
- allergic reactions
- loss of appetite
- obstruction of the bowel
- stomach ache
- weight loss.
Migrating proglottids can cause:
- inflammation of the appendix)
- inflammation of the bile duct)
- unpleasant surprise when seen in the feces.
Your health care provider makes the Taenia saginata
diagnosis by identifying eggs or proglottids. Eggs and proglottids start appearing in the
stool sample after three months of the start of the infection. During the first three months antibody
detection methods can be used to find antibodies from a blood sample. All Taenia species have similar
eggs so identification can only be done at the genus level. For educational purposes the specific species can
be identified by examining gravid proglottids. The diagnosis can also be done during an endoscopic
Treatment is traditionally done with an oral drug called praziquantel. It causes paralysis of
the worm by opening its membrane calcium channels. Then through peristaltic movements the tapeworm is defecated
out. Alternatively niclosamide can be used. Both drugs have some side effects (especially praziquantel) that are
similar to actual tapeworm infection symptoms. Endoscopic treatment is available in some areas. In the endoscopic
treatment a drug is injected straight to the small intestine. This causes all nearby tapeworms to detach and come
out whole. If the scolex (and neck) is left behind, it might produce new segments.
To prevent infection:
- Cook beef at or above 60 °C until it is no longer pink inside. Alternatively freeze the meat at or
below -5 °C for a few days.
- Prevent cattle from eating in areas, where vegetation might be contaminated with humans feces.
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