The largest tapeworms can be 80 feet or longer. Tapeworms harm their
host by stealing vital nutrients, causing malnutrition and if left
untreated can cause intestinal blockages.
Adult tapeworms share a basic body plan. All have a scolex, sometimes
colloquially referred to as the "head," a "neck,"
and one or more proglottids, which are sometimes called "segments,"
and which are the source of the name "tapeworm," because
they look like a strip of tape. All cestodes have a nerve ring in
the scolex with lateral trunks passing through the rest of the body.
The Scolex or "head" of the worm attaches to the intestine
of the definitive host. In some groups, the scolex is dominated
by bothria, which are sometimes called "sucking grooves,"
and which function like suction cups. Other groups have hooks and
suckers that aid in attachment. Cyclophyllid cestodes can be identified
by the presence of four suckers on their scolex, though they may
have other structures as well.
While the scolex is often the most distinctive part of an adult
tapeworm, it is often unavailable in a clinical setting, as it is
inside the patient. Thus, identifying eggs and proglottids in feces
The Neck of a tapeworm is a relatively undifferentiated mass of
cells that divide to form new proglottid "segments." This
is where all growth in an adult tapeworm occurs.
Posterior to the scolex, they have one or more proglottids that
hold the reproductive structures. The sum of the proglottids is
called a strobila. It is shaped thin like a strip of tape, which
is the source of the common name tapeworm. Like some other flatworms,
cestodes use flame cells (protonephridia) for excretion, which are
located in proglottids.
Mature or gravid proglottids are released from the mature tapeworm
and leave the host in its feces.
Because each proglottid can reproduce independently, it has been
suggested by some biologists that each should be considered a single
organism, and that the tapeworm is actually a colony of proglottids.
Tapeworms can be effectively cured with antiparasitic (antihelmintic)
medication once it is detected. Current Centers for Disease Control
and Prevention guidelines for treatment is a prescription drug called
praziquantel. The medication causes the tapeworm to dissolve within
the intestines. Praziquantel is generally well tolerated. Sometimes
more than one treatment is necessary.
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