A- Scolex provided with organs of fixation
B- Neck, active region for growth of segments
C- Chain of segments starting by:
-Immature segment.
-Mature segment.
-Gravid segment (filled by pregnant uterus full of ova).
Organs of fixation :
- 2 Slit like suckers and 4 cup shaped suckers with or without rostellum.
Development of coming CESTODES :
1- Adult tapeworms live in the small intestine of DH. All eggs pass mature (hexacanth embryo) in the feces.
2- Egg : Ingested by IH
3- embryo is liberated and penetrate intestinal wall and develops in organs into cystic larval stage.
4- This larvae when ingested by DH it develops into adult in intestine.
Example of cestodes : Taenia
- Bothe T.Saginata and T.Solium heve Same Mature segments squarish, common genital pores are not on same side.
- Gravid segments longer than broader, uterus has 15-20 (T.saginata) or 7 – 11 (T.solium) lateral branches full of eggs. Terminal segments separate to pass with stool or crawl at anal orifice.
Eggs (mature contain embryo) pass with stool of DH (man).
- It is ingested by IH (cattle in T.saginata and pig in T.solium) and embryo is liberated in intestine.
- Embryo pierces intestinal wall to blood vessel to reach muscles of IH to develop into cysticercus bovis containing no hooks (T. saginata) or cysticerus cellulosae containing hooks (T. solium)
Infective stage: Cysticercus bovis (T. saginata) or cysticercus cellulosae (T.solium).
- Mode of transmission is by eating raw or improperly cooked beef meat containing cysticercus bovis (T. saginata) or insufficiently cooked pork meat containing cysticercus cellulosae (T.solium).
- In small intestine of man, Scolex attaches to mucosa and by neck forms adult worm.
Clinical picture :
- Symptomless or associated with abdominal discomfort, vomiting, diarrhea.
- The main complaint is the passage of gravid segments with faeces or their crawling through the anal orifice and migration on the skin causing irritation& itching.
Diagnosis :
I. Clinical diagnosis:
1- history of passing segments.
2- Clinical picture.
II. Laboratory:
1- Stool examination for detection of eggs or gravid segments (diagnostic stages):
- 30-40 μ.
- Thick shell radially striated
- Contains hexacanth embryo
Treatment :
1- Praziquantel:10mg/kg single oral dose.
2- Yomesan: 2gm single dose. It is contraindicated in Taenia solium because it disintegrates gravid segments releasing eggs increasing risk of cysticercosis.
Prevention and control :
1-Treatment of patients.
2- Avoid eating insufficiently cooked meat.
3- Freezing of meat at -10C for 3 weeks kills cysticerci.
4- Proper inspection of meat in slaughter houses.
5- Avoid defecation in soil.
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