Human parasitology tapeworm2

1. Human parasitology (tapeworm2) Jin Liqun Department of Parasitology Shantou University Medical College lqjin@stu.edu.cn

2. Taenia solium (pork tapeworm) ?????,???? 

3. Morphology Adult : 2-4 m long, 700-1000 segments: Scolex Neck Immature segment Mature segment Gravid segment

4. Morphology Scolex: 1mm in diameter, a rostellum armed with two circles of hooks. ( armed tapeworm) four suckers Neck: The region for proliferation

6. Immature segment note that the reproductive organs are just beginning to differentiate. (Carmine stained)

7. Mature segments (proglottids) Hermaphroditic testes, sperm duct ovary, uterus genital pore vitellaria (yolk gland) excretory canal

8. Mature segment

9. Mature segment ( Ovary with 3 lobes)

10. Gravid segment Note : Less than 14 lateral uterine branches (one side) India ink stained

11. Cysticercus cellulosae (????,???)

12. Cysticercus cellulosae It is soybean-like in shape, has an small scolex invaginated into the translucent cyst. (left) The scolex evaginated from the cyst (right)

13. Cystcercus cellulosae in muscles of pigs (measly pork ???,???)

15. Scolex and Neck 1.5- 2 mm in diameter Without rostellum and hooks Four suckers ( unarmed tapeworm)

17. Mature segment (ovary with 2 lobes) Note : Bilobed ovary (Carmine stained)

18. Gravid segment India ink technique Note : More than 15 lateral uterine branches (one side).

19. Cysticercius bovis (????) Show invaginated scolex (left) show evaginated sscolex (right) The scolex is similar to that of adult worm in morphology

20. Cysticercus bovis Cysticercus bovis showing the bladder and the scolex (measly beef)

21. Taenia eggs (????) The eggs of Taenia saginata and T. solium are indistinguishable morphologically .

22. Taenia egg  spherical 31 to 43 �m a thick embryophore � an oncosphere inside ( ???) an egg shell outside (usually break away from the eggs in the feces)

23. Gravid segment ( the primary lateral branches of the uterus) Taenia solium Taenia saginata The uterus The uterus has 7 to 13 has 15 to 30 lateral branches lateral branches on each side on each side

24. Life cycle of Taenia solium Humans serve as final hosts as well as intermediate hosts in the life cycle of Taenia solium. ( both adult and bladder worm parasite in humans) 1 The adult worm lives in the small intestine of humans ( pork tapeworm infection) 2 The larvae (Cysticercus cellulosea, bladder worm ) localize and develop in pigs (intermediate host) 3 The cysticercus cellulosae may also infect humans causing cystcercosis (humans as intermediate hosts)

25. Life cycle of Taenia saginata The life cycle of Taenia saginata is similar to that of Taenia solium, but the intermediate host is cattle. The custicercus bovis (the beef bladder worm ) nearly does not parasite in human body. Humans serve as the final hosts only. (beef worm infection)

26. Life cycle

27. Life cycle of Taenia saginata and Taenia solium  Humans are the only definitive hosts for Taenia saginata and Taenia solium. Eggs or gravid proglottids are passed with feces The eggs can survive for days to months in the environment.� Cattle (T. saginata) and pigs (T. solium) become infected by ingesting eggs or gravid proglottids In the animal's intestine, the oncospheres hatch , invade the intestinal wall, and migrate to tissues, where they develop into cysticerci.

28. A cysticercus can survive for several years in the animal.� Humans become infected by ingesting raw or undercooked infected meat . In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine The adults produce gravid proglottids which detach from the tapeworm, and migrate to the anus or are passed in the stool.

29. Summary of life cycle Cysticercus cellulosae oncosphere (tissues and organs) (eggs of T.soloium) Adult gravid proglottids Human�s intestine or eggs Measly pork ingested by pig Ingested by human or cattle(in (measly beef in T.saginata) T.saginata) Cysticercus cellulosae oncosphere (in measly pork ) penetrate intestinal wall Cysticercus bovis into circulatory system, (in measly pork ) then to different tissues. (muscles and viscera)

30. Geographic Distribution Both species are worldwide in distribution.� Taenia solium is more prevalent in poorer communities where humans live in close contact with pigs and eat undercooked pork, and in very rare in Muslim countries.

31. Clinical Features Taenia saginata taeniasis produces mild abdominal symptoms and may cause malnutrition. (Epigastric pain, vomiting, diarrhea) The most striking feature consists of the passage (active and passive) of proglottids. The patients may find gravid proglottids themselves and take the segments to see doctors.� Occasionally, appendicitis or cholangitis(???)can result from migrating proglottids.

32. Taenia solium taeniasis is less symptomatic than Taenia saginata taeniasis.� The main symptom is often the passage (passive) of proglottids. The most important feature of� Taenia solium taeniasis is the risk of development of cysticercosis.

33. Laboratory Diagnosis Microscopic identification of eggs and proglottids in feces is diagnostic for taeniasis. Repeated examination and concentration techniques will increase the likelihood of detecting light infections. Species determination of Taenia is impossible if solely based on microscopic examination of eggs, because all Taenia species produce eggs that are morphologically identical.

34. Eggs of Taenia sp. are also indistinguishable from those produced by cestodes of the genus Echinococcus.� Microscopic identification of gravid proglottids (or, more rarely, examination of the scolex) allows species determination.

35. TAKE EXTREME CARE IN PROCESSING THE SAMPLES!� INGESTION OF EGGS CAN RESULT IN CYSTICERCOSIS! The prognosis(??) for intestinal taeniasis is good, but the infection should be terminated to reduce the risk of cysticercosis!

36. Diagnostic findings Microscopy: 1 egg * The eggs can not be used as species identification.

37. 2 scolex

38. Differential Morphology of the Diagnostic  stages of the two species: gravid segment

39. 3 gravid segment The most important diagnostic stage of the two species taeniasis.

42. Antibody detection may prove useful especially in the early invasive stages, when the eggs and proglottids are not apparent in the stools.

43. Summary on differentiations between the two species of tapeworms

44. Treatment: Treatment is simple and very effective.� Praziquantel*(???) is the drug of choice. * This drug is approved by the FDA, but considered investigational for this purpose. Traditional Chinese medicine: Areca nut(??)and pumpkin seed(???) therapy. FDA=Food and Drug Administration(??)????????

45. Cysticercosis Causal Agent:The cestode (tapeworm) Taenia solium (pork tapeworm) is the main cause of human cysticercosis.

46. Life Cycle

47. Cysticercosis is an infection of both humans and pigs with the larval stages of Taenia solium. This infection is caused by ingestion of eggs of a human tapeworm carrier. Pigs and humans become infected by ingesting eggs or gravid proglottids Humans are infected either by ingestion of food contaminated with feces, or by autoinfection.

48. In autoinfection, a human infected with adult T. solium can ingest eggs either through fecal contamination or, possibly, from proglottids carried into the stomach by reverse peristalsis(???).

49. Three Modes of infection : 1 internal autoinfection 2 external autoinfection. 3 heteroinfection

50. Once eggs are ingested, oncospheres hatch in the intestine , invade the intestinal wall, and migrate to striated muscles, as well as the brain, liver, and other tissues, where they develop into� cysticerci. In humans, cysts can cause serious results if they localize in the brain, resulting in neurocysticercosis

51. Clinical Features The symptoms of cysticercosis are caused by the development of cysticerci in various sites. Of great comcern is cerebral cysticercosis (or neurocysticercosis), which can cause manifestations including seizures(??), mental disturbances, focal neurologic deficits, and signs of space-occupying intracerebral lesions.� Death can occur suddenly

52. Cerebral cysticercosis

53. Extracerebral cysticercosis can cause ocular, cardiac, or spinal lesions with associated symptoms Asymptomatic subcutaneous nodules and calcified intramuscular nodules can be encountered.

54. Cysticercosis Cysticercus cellulosae in heart ( Cardiac cysticercosis )

55. Ocular cysticercosis Patient may complain of blurred vision even blindness. serious symptoms usually occur after the death of the cysticercus?

56. Laboratory Diagnosis The definitive diagnosis consists of demonstrating the cysticercus in the tissue involved. Persons who are found to have eggs or proglottids in their feces should be evaluated serologically since autoinfection, resulting in cysticercosis, can occur.

57. Diagnostic findings Antibody detection provides a useful adjunct in specific diagnosis Improved imaging techniques such as CT and MR can be very useful in detecting cysticerci in various organs .

58. Antibody detection: Sera from patients with cysticercosis react with at least one of the specific proteins (left) whereas sera from patients with echinococcosis do not react with any of the seven diagnostic proteins.(right)

59. Treatment Infections are generally treated with anti-parasitic drugs in combination with anti-inflammatory drugs . Surgery is sometimes necessary to treat infection in the eyes, cases that are not responsive to drug treatment, or to reduce brain edema . The use of albendazole and praziquantel is controversial .

60. Cysticercus  (bladder worm)  It is soybean-like  in shape, has an  small scolex  invaginated into  the translucent cyst.  The cyst is filled with fluid.  The scolex is exactly  similar to that of  adult worm in  morphology

61. Summary