Taenia spp..

Cestodes - Taenia spp

1. Cestodes Taenia spp Hawler Medical University College of Medicine Prepared by: Aram Majeed Ibrahim Hussein

2. Medically important spp. of Taenia . T. saginata  (beef tapeworm ) T. solium   (pork tapeworm ) Taenia asiatica (Asian tapeworm) Taenia multiceps

3. Name of diseases caused by each spp. B oth species T. saginata and T. solium cause of Taeniasis . Taenia solium   pork tapeworm infections can lead to  cysticercosis which is a disease that can cause seizures .

4. Hosts Species Intermediate host Definitive host T. saginata cow, cattle human T. Solium pig, human human Habitat Adult worms of both species live in the small intestine (upper jejunum) of man.

5. Intermediate hosts and definitive hosts of T. asiatica and T. multiceps Intermediate hosts … T. asiatica : pig . T. multiceps : sheep , cattle, horse other herbivores animals Definitive hosts ….. T. asiatica : Human T. Multiceps : Human , dog , wolf and fox

6. Morphology of Taenia saginata T . saginata  is a long flattened ribbon-like tapeworm that is white in color . It is about 6 to 7 milimeters in width . The adult  T. saginata  usually grows to be about 4 to 8 meters in length, with about 1000 segments called proglottids . Unlike the  T. solium , the scolex is " unarmed " because it has 4 suckers but no hooks.

7. Morphological differences Aspect Taenia saginata Taenia solium Adult size Longer (4-8 m) Smaller (4-2 m) Scolex 2 mm in diameter with 1 mm in diameter with 4 suckers 4 suckers but no hooklets and hooklets Number of segments 1000 – 2000 700 – 1000

8. Taenia scolex Taenia saginata Taenia solium

9. Taenia Adult worm Taenia solium Taenia saginata

10. Taenia solium

11. Taenia saginata

12. Aspect Taenia saginata Taenia solium Mature segment 2 ovary lobes 3 ovary lobes Gravid segment 15 - 30 uterine branches 7 -13 uterine branches Larvae Cysticercus bovis only in cattle, no scolex no hooklets Cysticercus cellulosae in pig and man,scolex with hooklets Egg in both species are indistinguiable Morphological differences

13. Taenia mature segment Taenia solium Taenia saginata

14. Taenia Gravid Proglotid Taenia solium Taenia saginata

15. Egg The eggs of Taenia saginata and T. solium are indistinguishable morphologically. The eggs are spherical, diameter 31 to 43 µm, with a thick radially striated brown embryophore . Inside each is an oncosphere with 6 hooklets .

16. Life cycle of Taenia spp

17. Life cycle of Taenia solium

18. Neurocysticercosis

19. Ophthalmic Cysticercosis

20. Cysticercosis in muscles

21. Mode of transmission Taenia saginata Man acquires infection by eating raw or undercooked beef containing encysted larval stage ( C ysticercus bovis ).

22. Mode of transmission Taenia solium ; man acquires infection by: 1- Eating raw or undercooked pork containing encysted larval stage ( Cysticercus cellulosae ). 2- Ingesting the egg with contaminated food or water . 3- A man harbouring adult worms may auto-infect either by unhygienic personal habits or by reverse peristaltic movements of the intestine whereby the gravid segments are thrown into the stomach.

23. Infective stage T aenia saginata Cysticercus bovis Taenia solium Cysticercus cellulosae and egg Diagnostic stage Taenia saginata gravid proglottids and egg Taenia solium gravid proglottids and egg T . asiatica …… cysticercus T. multiceps …. Eggs

24. Pathogenesis Usually no symptoms, m ay cause abdominal discomfort, indigestion, diarrhea alternating with constipation and loss of appetite . Cysticercosis (by cysticercus cullulosae ) may occur in any organ . May develop in subcutaneous tissue and form visible nodules or in brain forming epileptic attacks, and interior vitreous chamber of the eye.

25. Laboratory diagnosis 1- Stool microscopy; same for both Taenia , by demonstration of eggs or gravid proglottides in stool by: A- D irect fecal smear B- B rine floatation technique C- C ellophane-tape technique NOTE ; acid fast stain is used to distinguish the eggs, T.saginata is acid fast positive (red) while T.solium is negative (blue) or by detection of proglottids & scolex in feces.

26. Laboratory diagnosis cont.. 2. Detection of Taenia Ag in faeces ; Coproantigen is the most sensitive method (95 % sensitivity and 99% specificity) to detect Taenia specific Ag in the stool but does not differentiate between species. 3- Molecular diagnosis; Includes DNA probes & PCR

27. Diagnosis of cysticercosis 1- Biopsy of subcutaneous nodule ( cysticerci ) 2- X-ray (calcified cysticerci ), CT scan & MRI for neurocysticercosis . 3- Histopathological diagnosis ( cysticercus in autopsy tissue). 4- Serological tests (IHA, IFA & ELISA anticysticercus Ab ). 5- Differential leucocyte count (eosinophilia )

28. Treatment Praziquantel and niclosamide single dose of 4 tablets of 500 mg for T. saginata and T. solium . Praziquantel high dose over 3-7 days for T. solium .