Beef tapeworm / Hookless tapeworm Beef tapeworm infection Taenia saginata Beef tapeworm / Hookless tapeworm Taeniasis saginata or Beef tapeworm infection

Tapeworms

The beef tapeworm (Living specimen) 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm The beef tapeworm (Living specimen)

Adult Tapeworms

SEM of a Scolex

Epidemiology: These cestodes have a worldwide distribution, but incidence is higher in developing countries. Human infection follows consumption of raw and undercooked beef. Cysticerci can be seen as shiny white spots in infected beef on visual inspection. Former popular practice of prescribing beef juice or raw beef for debilitated persons responsible for many infections.

Epidemic factors: Egg or gravid proglottid contamination of grass and soil. Method of raising domestic animals. Unhygienic dinning habit of eating raw or undercooked meat.

Morphology: Adult habitat is in the middle third of small intestine. T. saginata can be up to 4 - 6 meters long or sometimes up to 24 meters and 12 mm broad. It has a pear-shaped head (scolex) with four suckers and a single apical depression, but no hooks. It has a long flat body with 1000-2000 segments (proglottids), of them 1/3-1/2 are nearly gravid.

Scolex with 4-suckers and a single apical depression

Only a single specimen occurs in an infection, but there may be more Only a single specimen occurs in an infection, but there may be more. Live up to 10 years or more. Proglottid: the more distal increase in breadth and width reach to 12 mm. Mature proglottid contains a full set of function ♂ and ♀ reproductive organs.

Taenia SPP. Mature Segment ( 12 mm )

Gravid proglottid more elongated, narrow as a result of the development of the large number of branched lateral arms of the uterus(15-20). The terminal proglottids become separated from the strobila and migrate out of the bowel or are evacuated in the stool with only partial loss of eggs.

Gravid proglottid of T. saginata Taenia saginata Gravid proglottid , India ink technique. Note : More than 14 lateral uterine branches (one side). 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Gravid proglottid of T. saginata

The egg is 31 x 43 micrometers, roundish and yellow-brown The egg is 31 x 43 micrometers, roundish and yellow-brown. It has a thin transparent outer embryonic envelop and a thick brown shell composed of many slender rods cemented together. It contains hexacanth embryo, which has 3-pairs of delicate lancet-shaped hooklets.

With Iodine With stain Taenia spp Egg.

Liberated by rupture of ripe proglottids. Does not float in saturated salt solutions. Eggs are resistant and remain viable for 8 weeks. Infective only to cattle.

Taenia spp. Egg Can not differentiate T. saginata from T. solium eggs Wet mount. Note : Brown, striated embryophore. Can not differentiate T. saginata from T. solium 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Taenia spp. Egg Can not differentiate T. saginata from T. solium eggs

Life cycle: A tapeworm larval cyst (Cysticercus bovis) is ingested with poorly cooked infected meat. The larva escapes the cyst and passes to the small intestine (middle third of intestine) where it attaches to the mucosa by the scolex suckers.

The proglottids develop as the worm matures in 3 - 4 months The proglottids develop as the worm matures in 3 - 4 months. The adult may live in the small intestine as long as 25 years and pass gravid proglottids with the feces. Eggs extruded from the proglottid contaminate and persist on vegetation for several days and are consumed by cattle in which they hatch and form cysticerci. Man is the only natural definitive host of T. saginata and the infection results from eating raw beef.