1. Introduction to tromatodes
Phylum Platyhelminthes Class Trematoda Order Digenea

2. Morphology Adult worm Flattened (flatworm) and leaf like
Sucker: oral & ventral (fluke)
Body wall: musculo-tegumental sac
Parenchyma (structure between body wall and internal organs): connective tissue fibers, cells and space between them

4. Digestive tract: not intact i.e. no anal opening, caecum
Reproductive system: hermaphrodite (monoecious) exception of schistosome
Muscular system
Nervous system
Excretory system

5. Egg Size divergent Ovoid Operculum (exception of that of schistosome)
Content: ovum , vitelline cells, or miracidium

6. Egg of Clonorchis sinensis
Clonorchis sinensis egg.  These are small operculated eggs.  Size 27 to 35 µm by 11 to 20 µm.  The operculum, at the smaller end of the egg,  is convex and rests on a visible "shoulder".  At the opposite (larger, abopercular) end, a small knob or hooklike protrusion is often visible (as is the case here).  The miracidium is visible inside the egg.
Egg of Clonorchis sinensis

7. Egg of Paragonimus westermani
And a third example of a Paragonimus egg.  (Original image from a Japanese language site tentatively titled Internet Atlas of Human Parasitology.) 来源
Egg of Paragonimus westermani

8. Egg of Fasciolopsis buski
F.buski eggs are released in feces unembryonated. The operculated eggs are oval, brown and measure by um
Egg of Fasciolopsis buski

9. S. japonicum S. Mansoni S. haematobium
Schistosome egg

10. Features Reflecting Adaptation to Parasitism
Organs of attachment highly developed
Retardation of digestive system
Highly developed reproductive system

11. Life Cycle
Complex
Alteration of generation sexual generation and asexual generation alter in the life cycle of parasite
Asexual multiplication in larval stage in snail host
Multiple hosts transfer and having reservoir hosts in majority
Water environment is essential

12. Important Species Liver fluke: Clonorchis sinensis
Intestinal fluke: Fasciolopsis buski
Lung fluke: Paragonimous westermani P. skrjabini
Blood fluke: Schistosoma spp.

13. The Liver Fluke 肝吸虫 Clonorchis sinensis 中华支睾吸虫

14. Introduction Parasite of biliary passage Cause “clonorchiasis”
A common trematode in Far East
First report oversea Chinese in India

15. Morphology Adult worm Size & Shape like the seed of sunflower
Sucker: oral = ventral
2 dendritic testes lie in tandem to each other in the posterior region (clonorchis)

16. Adults of Clonorchis sinensis
Clonorchis sinensis adult
Adults of Clonorchis sinensis

17. Clonorchis sinensis, adult, stained whole mount; approximate size = 15 mm.  Click here to view a labeled image of this parasite, or here to view a labeled line drawing of this parasite. 来源

19. Cross section of Clonorchis sinensis adult in the hepatic bile duct
Clonorchis sinensis, liver biopsy: most infections are asymptomatic.
Cross section of Clonorchis sinensis adult in the hepatic bile duct

20. Egg Size: smallest Shape: just like sesame Color: yellowish brown
Operculum distinct: shoulder, knob
Content: miracidium

21. Clonorchis sinensis egg. These are small operculated eggs
Clonorchis sinensis egg.  These are small operculated eggs.  Size 27 to 35 µm by 11 to 20 µm.  The operculum, at the smaller end of the egg,  is convex and rests on a visible "shoulder".  At the opposite (larger, abopercular) end, a small knob or hooklike protrusion is often visible (as is the case here).  The miracidium is visible inside the egg.
Clonorchis sinensis egg.  These are small operculated eggs.  Size 27 to 35 µm by 11 to 20 µm.  The operculum, at the smaller end of the egg,  is convex and rests on a visible "shoulder".  At the opposite (larger, abopercular) end, a small knob or hooklike protrusion is often visible (as is the case here).  The miracidium is visible inside the egg.

22. Egg of Clonorchis sinensis
Clonorchis sinensis/ O.viverrini egg: eggs of the two species are similar. They measure by um are operculated at one end and have a small knob on the other end. The colour is yellow
Egg of Clonorchis sinensis

23. Life cycle of Clonorchis sinensis
Embryonated eggs are discharged in the biliary ducts and in the stool .  Eggs are ingested by a suitable snail intermediate host ; there are more than 100 species of snails that can serve as intermediate hosts.  Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ).  The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae .  Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish .  After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater .  Maturation takes approximately 1 month.  The adult flukes (measuring 10 to 25 mm by 3 to 5 mm) reside in small and medium sized biliary ducts.  In addition to humans, carnivorous animals can serve as reservoir hosts.
Life cycle of Clonorchis sinensis

24. Life Cycle A model pattern of trematode Main points
Definitive host: human being
Reservoir host: dog, cat, etc.
Residing: hepatic bile duct
Discharge of eggs with feces

25. Hatching in the host small intestine
2 intermediate host I: snails, such as Bithynia,Parafossarulus II: freshwater fishes, such as Cyprinus
2 generation of asexual proliferation
Infective stage: metacercaria in fish
Infective route: oral consumption

26. Pathogenesis Due to adult worm Mechanism Mechanical: sucker
Chemical: excretions, secretions, metabolite
Biological: nutrition deprivation

27. Pathological process Inflammation Proliferation ThickeningOcclusion
Extensive involvementFibrosis of the liver

28. Clinical Manifestations
Acute stage: allergic reaction
Chronic stage: functional impairment of liver (Cholangitis, Cholecystitis, Bile stone, Jaundice, etc)
Advanced stage: portal cirrhosis & malignancy

29. Laboratory Diagnosis Etiological Immunological
Examination of egg in feces by sedimentation method
Duodenal aspiration
Immunological
ELISA to detect antiboby or antigen

30. Epidemiology Distribution Far East (China, South Korea, Japan, etc.)
24 provinces in China (Guangdon: 5 million infected etc.)

31. Clonorchis sinensis/Opisthorchis viverrini: geographic distribution.

32. Endemic Factors Source of infection: mainly wild carnivores
I,II intermediate host in the same water-field
Mode of fish breeding
Dinning habit & Customs

33. Principle of Control Cure patients & carrier
praziquantel:25mg/kg, tid, 2 days
Control reservoir host
Carry out scientific fish-breeding
Hygienic education not eating raw or undercooked fishes

34. Paragonimus westermani 卫氏并殖吸虫 Paragonimus skrjabini (Paragonimus szechuanensis) 斯氏狸殖吸虫

35. The Lung Fluke Genus paragonimus Zoonotic parasite (cause zoonosis)
Animal infection> human infection
2 major species in China

36. Introduction Pathogen of lung disease Endemic hemoptysis
Favorite lodging site: lung
Ectopic site: brain, abdomen, muscle, etc.

37. Morphology Adult worm Body thick (a half piece of a bean grain)
Tegument: spinous
Sucker: oral = ventral
Parallel arrangement of reproductive organ lobular testes (posterior) lobular ovary & uterus (anterior)

38. Paragonimus westermani, adult, stained whole mount; approximate size = 9 mm in length.  Click here to view an image in which some of the internal organs are labeled, or click here to view a labeled line drawing 来源

39. Cross section of lung containing adult Paragonimus westermani.

40. Egg Median size, ovoid (water pot) Golden yellow
Distinctive & wide operculum
Contain 1 germ cell & several yolk cells

41. Egg of Paragonimus westermani.
And a third example of a Paragonimus egg.  (Original image from a Japanese language site tentatively titled Internet Atlas of Human Parasitology.) 来源
Egg of Paragonimus westermani.

42. Life cycle of Paragonimus westermani.
Crab or crayfish
The eggs are excreted unembryonated in the sputum, or alternately they are swallowed and passed with stool .  In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues .  Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , which emerge from the snail.  The cercariae invade the second intermediate host, a crustacean such as a crab or crayfish, where they encyst and become metacercariae.  This is the infective stage for the mammalian host .  Human infection with P. westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite .  The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5 to 12 mm by 4 to 6 mm).  The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively.  However, when this takes place completion of the life cycles is not achieved, because the eggs laid cannot exit these sites.  Time from infection to oviposition is 65 to 90 days.  Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P. westermani.
Life cycle of Paragonimus westermani.

43. Life cycle Definitive host: human being
Reservoir host: carnivorous animals
Habitation: lung & ectopic site
Intermediate host: I: Melania snails II: stream crabs, crayfish

44. Infective stage: metacercaria
Infective mode: oral route, may via paratenic host (swine)
Migration & Preadult wondering
Ectopic parasitism: cerebral, abdominal,etc.
Eggs discharged with sputum & feces
3 generation of asexual multiplication

45. Metacercariae of Paragonimus westermani.来源

46. Pathogenesis Stage take responsibility: adult & preadult
Pathological processes
Abscess stage(脓肿期)
Cystic stage(囊肿期)
Scar formation stage(纤维疤痕期)

47. 4 clinical types
Thoracic (pulmonary type):chest pain, coughing, blood-tinged sputum(hemoptysis)
Abdominal (hepatic type):hepatomegaly
Cranial type: dizzy, headache, epilepsy
Musculocutaneous type: migratable subskin nodule

48. Laboratory diagnosis Disease history + physical examination
Etiological diagnosis eggs in sputum or feces by sedimentation
Immunological diagnosis for ectopic infections

49. Epidemiology
Global main continent except Europe
China 23 provinces

50. Paragonimus westermani infection occurs in Asia (especially in China, Corea, India, Japan, Laos, Philippines, Sri Lanka, Taiwan, Thailand, Viet-Nam), Central-West Africa, South America (Ecuador, Per? Venezuela).
Paragonimus westermani infection occurs in Asia (especially in China (Taiwan), Corea, India, Japan, Laos, Philippines, Sri Lanka, Thailand, Viet-Nam), Central-West Africa, South America (Ecuador, Peru Venezuela).

51. Principle of control Treat patient: praziquantel Hygienic education
Social construction, economic refinement

52. The Ginger Fluke 姜片虫 Fasciolopsis buski 布氏姜片吸虫 Intestinal fluke 肠道吸虫

53. Morphology Adult worm Like a ginger piece Big muscular trematode
Have strong suckers，ventral >> oral

54. Adult fluke of Fasciolopsis buski
Adult fluke of Fasciolopsis buski.  The adult flukes range in size: 20 to 75 mm by 8 to 20 mm.  Image contributed by Georgia Division of Public Health.
Adult fluke of Fasciolopsis buski The adult flukes range in size: 20 to 75 mm by 8 to 20 mm

55. Fasciolopsis buskii adult worm

56. Egg
Biggest
Ovoid
Minute operculum
Yellowish
Germ cell inclusions

57. F. buski eggs are released in feces unembryonated
F.buski eggs are released in feces unembryonated. The operculated eggs are oval, brown and measure by um
F.buski eggs are released in feces unembryonated. The operculated eggs are oval, brown and measure by um

58. Life cycle of Fascilopsis buski
Immature eggs are discharged into the intestine and stool .  Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host .  In the snail the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ).  The cercariae are released from the snail and encyst as metacercariae on aquatic plants .  The mammalian hosts become infected by ingesting metacercariae on the aquatic plants.  After ingestion, the metacercariae excyst in the duodenum and attach to the intestinal wall.  There they develop into adult flukes (20 to 75 mm by 8 to 20 mm) in approximately 3 months, attached to the intestinal wall of the mammalian hosts (humans and pigs) .  The  adults have a life span of about one year.
Life cycle of Fascilopsis buski

59. The adult flukes (20 to 75 mm by 8 to 20 mm) reside in the duodenum and jejunum of mammalian hosts (humans and pigs), where they are attached to the intestinal wall.  Immature eggs are discharged into the intestine and stool.  After development in water, each egg releases a miracidium which invades a suitable snail intermediate host.  In the snail the parasites undergo several developmental stages (sporocysts, rediae, and cercariae).  The cercariae are released from the snail and encyst as metacercariae on aquatic plants.  The mammalian hosts become infected by ingesting metacercariae on the aquatic plants.  After ingestion, the metacercariae excyst in the duodenum and attach to the intestinal wall.  They develop in approximately 3 months into adults, which have a life span of one year.  Fasciolopsis buski infects humans and pigs.

60. Life Cycle Definitive host: human being Reservoir host: swine, etc.
Intermediate host: Planorbis snails
Aquatic plant vectors: caltrops, water chestnut, etc.
Habitation: small intestine

61. Infective stage: metacercaria
Infective route: oral
Developmental stages: as Paragonimus
3 generation of asexual proliferation

62. Pathogenesis Factors Traumatic (suckers) Obstructive (due large size)
Toxic (excretion, secretion, metabolite)

63. Clinical Manifestation
Abdominal pain
Acute intestinal obstruction
Anemia
Generalized edema

64. Laboratory Diagnosis
Examination of egg in feces by sedimentation method

65. Epidemiology
Aquatic plant raising districts

66. Fasciolopsis buski: is endemic in China, Taiwan, South-East Asia, Malaysia and India.

67. Principle of Control Drug for treatment: praziquantel
Water & nightsoil control; Scientific swine raising
Hygienic education

68. Introduction 6 species of human schistosomes Schistosoma japonicum
S. mansoni
S. haematobium
S. intercalatum
S. mekongi
S. malayi

69. Schistosoma japonicum
日本血吸虫

70. Distribution and Epidemic Situation
Worldwide
200 million of population infected in 74 countries (S.m. 55; S.h. 55; S.j. 4; S.i. 10; S.me. 2; S.ma. 1)
China
11 million in 12 provinces  0.7 million in 8 provinces
50 years

71. Regional distribution of S. japonicum infection in China
Before control After control (1996)
Regional distribution of S. japonicum infection in China

72. Morphology Difference from other trematodes Dioecious adults
Non-opeculate egg
Bifurcated (forked) cercaria invades the final host by skin
Adults parasitize blood vessels

73. Adult Male (15 mm length) < female (22 mm)
Oral sucker < ventral sucker
2 paralleled guts form a blind caecum in the posterior ends
7 testes in male and single ovary with a tubule uterus in female
Gynecophoric canal (male) in which female repose

75. adult schistosomes live in pairs in the portal system and in mesenteric venules; adults of S.japonicum are bigger than adults of S.mansoni. males are mm in lenght and 0,5 wide, and have a ventral infolding from the ventral sucker to the posterior end forming the gynecophoric canal. Adult male with female in the copulatory groove

76. A scanning electron micrograph of schistosomes in copula

77. Egg Miracidium Cercaria Ovoid and non-opeculate 74~106 m × 55~80 m
Contains one miracidium
Bear a minute lateral knob.
Miracidium
Cercaria

78. S. japonicum S. Mansoni S. haematobium
Schistosome egg

79. Schistosome miracidium

80. cercarae are the infective forms. They measure about 500 micron
cercarae are the infective forms.  They measure about 500 micron. After encountering the skin,  the cercariae penetrate and lose the tail transforming into schistosomulae
Schistosome cercaria

81. Life Cycle
Eggs discharged  fresh water (hatch)  miracidia  penetrate oncomelania(I.H.)mother sporocysts (multiplication)  daughter sporocysts (multiplication)  cercariae (infective form)  skin penetration of D.H.  schistosomulum  right heart  lungs  left heart  systemic circulation  portal system  pairing and sexual maturation  mesenteric veins lay eggs eggs develop and live in tissue for 21 days( 23% in liver tissue, 60% in intestinal tissue, 17% discharged)

83. Cercarial dermatisis due to avian schistosome
Typically, hosts of avian schistosomes are migratory water birds, including shorebirds, ducks, and geese.  Adult worms are found in the blood vessels and produce eggs that are swallowed and passed in the feces.  On exposure to water, the eggs hatch and liberate a ciliated miracidium that infects a suitable molluscan intermediate host.  The parasite develops the in this intermediate host, usually a certain species of snail, to produce free-swimming cercariae that are released under appropriate conditions and penetrate the skin of the birds to complete the cycle.  Humans are inadvertent and inappropriate hosts; cercariae may penetrate the skin but do not develop further.  A number of species of dermatitis-producing cercariae have been described from both freshwater and saltwater environments, and exposure to either type of cercariae will sensitize persons to both.
Cercarial dermatisis due to avian schistosome

84. Main Points of Life Cycle
Residing site: mesenteric vein
I.H.(Only one): Oncomelania hupensis
No metacercaria and redia stage
Two generation of sporocyst
Infective stage: cercaria
Route of infection: skin penetration

85. Adult of Schistosome in mesenteric veins of hamster
S.mansoni : Females are slender (1 mm in diameter)  and longer (9-17 mm in lenght), and are held in the ginecophoric canal during copulation. Each female lays about 300 eggs per day. Adult male with female in the copulatory groove.  Adult of S.mansoni in mesenteric veins of hamster.
Adult of Schistosome in mesenteric veins of hamster

86. Onchomelania hupensis
intermediate host of S.japonicum are snails of the genus Onchomelania, hupensis spp.
Onchomelania hupensis

87. Skin penetration of cercaria  first appearance of eggs: 30~35 days
Life spans in human: 4~5 years, longest: 35 years

88. Significance of tissue egg
The egg which can develop and live in tissue
Significance of tissue egg
Major pathogenic stage, inflammation and granuloma around the egg
Diagnosis and evaluation of therapeutic efficacy

89. Immunity Concomitant immunity
Host carrying an initial infection of adult schistosomes shows the protection to a cercarial challenge infection (攻击性感染）and this protective immunity will disappear with eradication of schistosomes in the host

90. Immuno-evasion: It’s an ability by which the schistosome adult can evade the host immune response. The possible mechanism of evasion.
Acquire host antigen on it surface
Host-like antigen produced by parasite
Changing of tegument very quickly
Parasite may inactivate or down-regulate immune effectors

91. Pathogenesis
Schistosomiasis at each stage of the life cycle in human body
Cercaria (skin-penetration)
Dermatitis
Schistosomula (migration)
Larva migrans
Adult: (immunocomplex)
Immuno-nephropathy

92. Tissue egg: principal pathogenic stage
Miracidium within eggSEASensitization of T Cell
Th1IL-2, INF-, TNF  activate macrophage, induce  cell-mediated immunity
Th2IL-4, IL-5 stimulate IgE production or eosinophilia
inflammation and granuloma  fibrosis portal hypertension  intestinal polyp

93. Clinical Form Acute schistosomiasis Chronic schistosomiasis
Fever, diarrhea, abdominal pain, enlargement of liver or spleen
Chronic schistosomiasis
asymptomatic or diarrhea, abdominal pain, enlargement of liver or spleen
Advanced schistosomiasis
Ascites; splenomegaly;collateral circulation; dwarfism;
Ectopic lesion: encephalitis; focal epilepsy

94. Advanced schistosomiasis patient with portal hypertension and ascites
Brazilian with portal hypertension and ascites due to S.mansoni.
Advanced schistosomiasis patient
with portal hypertension and ascites

95. A patient with S. j has marked ascites, splenomegaly, umbilical hernia and distended superficial abdominal veins.

96. Diagnosis
Parasitological diagnosis (etiological, definitive diagnosis)
Demonstrating eggs by stool examination
Stool examination after concentration (sedimentation)
*Miracidium-hatching from eggs
Rectal biopsy — eggs-demonstration

97. Miracidium-hatching from eggs
Necessity: tissue ova;
low egg burden due to mass treatment
Possibility:
Hatch quickly (T:25; limpid water; free of Cl2;light; pH= )
Three tropism:limpidity, phototrophic, ascendancy
Swimming in a zigzag way

98. Immunodiagnosis (indirect diagnosis)
Detection of antibodies in serum, urine, saliva by ELISA, but is impossible to distinguish current infection from past infection.
Detection of antigens (circulation anodic and cathodic antigen)

99. Combined diagnosis: including epidemiological antecedent, symptoms and signs, parasitological and immunological examination.

100. Treatment
Praziquantel 60 mg/kg divided in 3 doses.

101. Factors of Transmission and Prevention
Source of infection: patients and reservoir host
Intermediate host: Oncomelania
Contact with cercaria-infected water

102. Preventive measures
Detection and treatment of patients and reservoir host
Elimination or control of oncomelania
Protection of susceptible population and avoidance of contact with cercaria-infected water
Prevention of water contamination by human night soil

103. Distinguishing of 3 major schistosomes
(see page 54, Table 3-1)