tapeworms: general characters

TAPEWORMS:

GENERAL CHARACTERS

“Mkhitar Gosh” University, Armenia

Medical biology courses : Lecture N 25

Cestodes (Greek Kestos — girdle or ribbon) are

segmented tape-like worms whose sizes vary from a few

millimetres to several metres. The adult worm consists of three

parts — the head, neck and trunk. The head (scolex) carries

grooved or cup-like suckers, which are the organs of

attachment to the intestinal mucosa of the definitive host,

human or animal. The neck, immediately behind the head is

the region of growth, where the segments of the body are

being continuously generated. The trunk (called strobila) is

composed of a chain of proglottides or segments. The

proglottides near the neck are the young immature segments,

behind them are the mature segments and at the hind end are

the gravid segments

EPIDEMIOLOGY

T. solium is found everywhere in the world. However,

prevalance of T. solium are high in Mexico, Central and

South America, Africa, Asia, Spain, and Portugal. Areas of

poor sanitation, large fecal human contamination, and areas

where pigs or swines graze have high rates of T.solium

infection. Countries where people like to eat their meat

undercooked (like some parts of Europe and Asia) also have

high infection rates. Taeniasis and cysticercosis are very rare

in Muslim countries.

Cysticercosis outside the central nervous

system is treated surgically. For patients

with ocular cysticercosis, the cysts are

removed. Excisonal biopsies are

performed on subcutaneous cysticercosis.

For patients with brain cysticercosis, two

drugs praziwuantel and albendazole are

relatively successful as treatments. The

prognosis for a patient with adult

tapeworms that can be removed surgically

or medically treated is good. The

prognosis for patients with racemose form

of the parasite is bad.

Indicate the system which Cestodes have not:

A digestive system

B excretory system

C nervous system

D respiratory system

E genital system

What is the characteristic feature of gravid proglottid of

Taenia solium?

A 17 –35 uterine branches

B 7 –12 uterine branches

C bilobed ovary

D trilobed ovary

E gravid uterus is in the form of rosette