The document describes key anatomical structures and life cycles of various fluke parasites (trematodes) that infect humans, including Schistosoma species, Clonorchis sinensis, and Opisthorchis species. It provides diagrams of adult worm anatomy and egg morphology for S. japonicum, S. mansoni, and S. haematobium. Clinical manifestations of infections can include abdominal pain, diarrhea, hepatomegaly, and in some cases cholangiocarcinoma. Control relies on improving sanitation and targeting intermediate snail hosts.

2. Flukes (Trematods)

4. Body surface
o.s.-oral sucker
v.s.-ventral sucker
s-spine

5. The Digestive
System
p-pharynx
e-esophagus
c-intestine

6. the shape and
length of the
intestinal ceca

7. Schistosoma sp.

8. Male Reproductive
System
g.o. - genital opening
s.v. – seminal vesicle
v.d. – vas deferens
v.e. – vas eferens
t- testis

9. Male Reproductive System-
details
g.o.- genital opening
g.a. – genital atrium
u - uterus
cr.- cirrus
cr.s.- cirrus sinus
p.g.- pouch glands
s.v.- seminal vesicle
v.d.- vas deferens
v.e.- vas eferens
t- tetstis

10. the location, the shape,
and number of testes
Schistosoma sp.

11. Female
Reproductive
System
g.o.- genital openinig
u – uterus
m.g – Mehlis gland
l.c. – Laurer’s canal
s.r. – seminal receptacle
ov. – ovary
vt. d. – vitelline duct
oot. - ootype
vt. - vitellaria

12. Female reproductive
system
Details
u – uterus
m.g – Mehlis gland
l.c. – Laurer’s canal
s.r. – seminal receptacle
ov. – ovary
vt. d. – vitelline duct
oot - ootype

13. Female reproductive system - details
Schistosoma sp.

14. The Nervous
System
c.g.- central ganglia
v.n.- ventral nerve cord
l.n.- lateral nerve cord
d.n.- dorsal nerve cord

15. The Excretory
System
e.c- excretory canal
f.c.- flame cell
b- excretory bladder
e.p.- ecretory pole

16. Functional and structural
unit of the excretory
system is flame cell.
Ciliated cells extending into
excretory tubules; in living state,
motion of cilia reminiscent of
flames and when seen under
microscope indicates viability.
n - nucleus
cl.- beating cilia
e.c.- excretory canal
arrows show the direction of the
waste fluid-products removal

17. • Some anatomical structures are used
for taxonomical differentiation:
the shape and length of the intestinal ceca,
the number of suckers their size and
location,
and the location, the shape, and number of
testes

18. KEY TO IMPORTANT ADULT
HUMAN TREMATODES
• 1. Dioecious trematodes (one sex per
worm)...................... Schistosoma species.
• Monoecious trematodes (both sexes per
worm)....................................................... 2
• 2. Small flukes: size under 5 mm..............3
• Large flukes: size range 20 to 45 mm.......4
• Medium flukes: size range 5 to 20 mm ....5

19. Dioecious
Monoecious
1 — Busephalus polymorphus, 1—2 мм;
2 — Fasciola hepatica, 30 мм;
3 — Dicrocoelium lanceatum, 10 мм;
4 — Opistorchis felineus, 10 мм;
5 — Echinostoma revolutum, 7—10 мм;
6 — Cyclocoelum mutabile, 12 мм;
7 — Schistosomum haematobium, 12—20 мм;

20. KEY TO IMPORTANT ADULT
HUMAN TREMATODES
• 3. Gonotyl absent; ventral sucker offset to
one side; intestinal ceca straight; testes
oval and oblique..........................................
Metagonimus yokogawai
• Gonotyl (genital sucker) present; ventral
sucker central; intestinal ceca straight;
testes oval and para ………………...............
Heterophyes heterophyes

21. Heterophyes heterophyesMetagonimus yokogawai

22. KEY TO IMPORTANT ADULT
HUMAN TREMATODES
• 4. Cephalic cone present; intestinal ceca
branched; testes tandem and dendric.............
Faciola hepatica
• Cephalic cone absent; intestinal ceca
undulating; testes tandem and dendric............
Faciolopsis buski
• 5. Anterior testes ……………………………..6
• Posterior testes ……………………………….7

23. Faciola hepatica Faciolopsis buski

24. KEY TO IMPORTANT ADULT
HUMAN TREMATODES
• 6. Intestinal ceca straight; testes oblique
and lobate; wide acetabulum at posterior
end; gourd-shaped body.............................
Gastrodiscoides hominis
• Intestinal ceca straight; testes oblique and
lobate; elongated........................................
Dicrocoelium dendriticum

25. Gastrodiscoides hominis
Dicrocoelium dendriticum

26. KEY TO IMPORTANT ADULT
HUMAN TREMATODES
• 7. Circlet of spines around oral sucker; intestinal
ceca straight; testes tandem and lobate……….
…….…………………...… Echinostoma species
• Intestinal ceca straight; testes oblique and lobate
………………………........... Opisthorchis species
• Intestinal ceca straight; testes tandem and highly
branched........................... Clonorchis sinensis
• Intestinal ceca undulating; testes para and
lobate………............... Paragonimus westermani

28. Clonorchis sinensis

30. Clonorchiasis
• Symptoms
• The worm causes irritation of the bile ducts
which become dilated and deviated.
• The liver may enlarge, become necrotic and
tender and its function may be impaired.
• Modest infections results in indigestion,
epigastric discomfort, weakness and loss of
weight.
• Heavier infections produce anemia, liver
enlargement, slight jaundice, edema, ascites
and diarrhea.

31. Clonorchiasis
• Most pathologic manifestations result from
inflammation and periodical obstruction of the biliary
ducts.
• In the acute phase, abdominal pain, nausea, diarrhea,
and eosinophilia can occur.
• In chronic infections, cholangitis, hepatosplenomegaly,
pancreatitis, and cholangiocarcinoma can develop,
which may be fatal.

32. • The adults live in the distal bile ducts and may
survive for 30-40 years, causing irritation to
biliary cells and inflammation.

33. • Most infections are asymptomatic.
• Clinical manifestations can be observed in adults due to
obstruction and dilatation of biliary ducts, cholangitis and in
some cases cholangiocarcinoma.

34. Cholangiocarcinoma (CCA)
• Cholangiocarcinoma is a relatively
rare type of primary liver cancer that
effects the biliary system, used to
transport bile from the liver to the
intestines.
• The malignancy originates in the bile
duct epithelium and represents less
than 10% of primary hepatic
malignancies.
• Risk factor for the development of
cholangiocarcinoma include long
standing inflammation and chronic
injury of the biliary epithelium.
Chronic C. sinensis and Opisthorchis viverrini infection is associated with
cholangiocarcinoma of the bile duct system, which can extend into the liver
as shown here.

35. • A section of C. sinensis from the liver shows a large
Sucker on the destroyed epithelium of an intrahepatic
bile duct. There are many ova in the uterus of the parasite.
Similar pathology would be evident in either O. viverrani or O. felinus.

36. • Opisthorchis
species

38. Opisthorchiasis
• Most infections are asymptomatic.
• In mild cases, manifestations include dyspepsia, abdominal pain,
diarrhea or constipation.
• Infections of longer duration, the symptoms can be more severe, and
hepatomegaly and malnutrition may be present.
• In rare cases, cholangitis, cholecystitis, and chlolangiocarcinoma may
develop.
• Acute phase resembling Katayama fever (schistosomiasis), with fever,
facial edema, lymphadenopathy, and eosinophilia.
• Chronic forms of O. felineus infections present the same manifestations
as O. viverrini, with in addition involvement of the pancreatic ducts.

39. The human schistosomes (blood flukes) are digenic trematodes of
the superfamily Schistosomatoidea.
The adult worms inhabit the mesenteric veins
(S.mansoni, S.japonicum, S.mekongi, S.intercalatum)
or the veins of the vesical and pelvic plexuses (S.haematobium).

40. The life cycle is
common to all
species with a
sexual
generation in
vascular system
of the definitive
host and an
asexual
generation in the
intermediate
host (mollusca)

41. After 35 days (S.japonicum, S.mansoni) and 70 days (S.haematobium) embryonated
eggs are excreted in faeces and/or urine.
In the hepatic
circulation
schistosomes
mature to adult,
and in pairs they
migrate to the
mesenteric veins
(S.japonicum
S. mansoni)
and to the
vesical plexus
(S.haematobium)

42. Blood flukes
miracidium penetrates snail, transforms into
1st and 2nd generation of sporocyst than hatch into
furkocerkaria,
there is no redia and metacercaria stage
there are unique schistosomulae stage

43. furcocercaria- infectiv stage
egg
miracidium

44. Control of schistosomiasis is difficult.
The control of snails is critical; environmental sanitation,
safety of supply water and education are essential.
Collecting snails

45. Molluscisciding spraying
Molluscisciding drip feeding

46. Schistosoma japonicum
• COMMON NAME: Oriental blood fluke
• GEOGRAPHICAL DISTRIBUTION: Far East
• PATHOGENESIS: Embolic eggs cause more severe
lesions than other schistosome, splenomegaly, cellular
species, infiltration of vital organs; liver, fibrosis and
cirrhosis, infiltration, ulceration.
• HABITAT: Venules surrounding the small intestine.
• INTERMEDIATE HOST
• FIRST: Snail (Oncomelania).
• SECOND: None.
• RESERVOIR HOST: Mammals.
• INFECTIVE FORM: Cercaria= furcocercaria.
• MODE OF INFECTION: Active penetration.
• SPECIMEN OF CHOICE: Feces.

47. S.japonicum occurs in Southeast Asia and western Pacific
countries (including China, the Philipines and Indonesia).

48. • MALE: 1.0 to 2.2 cm long
by 0.5 mm wide.
• FEMALE: 1.2 to 2.6 cm
long by 0.3 mm wide.
• SHAPE: Elongated with
gynecophoral canal in
males.
• COLOR: Greyish white.
• TESTES: Anterior (6 to 8)
• OVARIES: Middle of body
• UTERUS: Long with 50 to
100 ova.
S.japonicum

49. SIZE: 90 x 70 µm (medium).
SHAPE: Oval to round
COLOR: Yellow brown
OPERCULUM: Absent
CONTENT: Shouldered with miracidium
surrounded by vitelline membrane (double
linear outline); short lateral spine
sometimes curved (inconspicuous).
Fecal debris adhering to shell
S.japonicum

50. Schistosoma mansoni
• COMMON NAME: Manson's blood fluke.
• GEOGRAPHICAL DISTRIBUTION: Central and North Africa;
Equatorial regions of South America; West Indies and Puerto Rico.
• PATHOGENESIS: Infiltration of vital organs; hemorrhages, anemia,
hepato-splenomegaly, liver cirrhosis, fibrous tissue proliferation,
ulcerations.
• HABITAT: Venules surrounding the large intestine.
• INTERMEDIATE HOST
• FIRST: Snail (Biomphalaria, Australorbis).
• SECOND: None.
• RESERVOIR HOST: Rarely monkeys.
• INFECTIVE FORM: Cercaria= furcocercaria.
• MODE OF INFECTION: Active penetration.
• SPECIMEN OF CHOICE: Feces.

51. S.mansoni is endemic in 43 countries in Africa and occurs in the
americas in Brazil, Suriname, Venezuela and in the Caribbean.

52. • MALE: 0.6 to 1.4 cm long by
1.1 mm wide.
• FEMALE: 1.2 to 1.6 cm long by
0.2 mm wide.
• Each female lays about 300
eggs per day.
• SHAPE: Elongated with
gynecophoral canal in males.
• COLOR: White to cream
• TESTES: Anterior (3 to 13).
• OVARY: In anterior half of
body.
• UTERUS: Short with 1 to 5 ova
S.mansoni

53. • SIZE: 155 x 65 µm
(large).
• SHAPE: Elongated.
• COLOR: Yellow brown.
• OPERCULUM: Absent.
• CONTENT: Shouldered
miracidium surrounded
by vitelline membrane
(double linearoutline).
• Large lateral spine.
S.mansoni

54. Schistosoma haematobium
• COMMON NAME: Vesical blood fluke.
• GEOGRAPHICAL DISTRIBUTION: Africa; Asia Minor;
Mediterranean regions.
• PATHOGENESIS: Toxic irritations, lesions of urinary
bladder and genitalia, cystitis, occlusions of ureters and
urethra, hematuria, eosinophilia.
• HABITAT: Venules surrounding the urinary bladder.
• INTERMEDIATE HOST
• FIRST: Snail (Bulinus, Biomphalaria).
• SECOND: None
• RESERVOIR HOST: None
• INFECTIVE FORM: Cercaria= furcocercaria.
• MODE OF INFECTION: Active penetration.
• SPECIMEN OF CHOICE: Urine (also feces)

55. • MALE: 1.0 to 1.5 cm long x
0.9 mm wide.
• FEMALE: 2.0 to 2.5 cm
long by 0.25 mm wide.
• SHAPE: Elongated with
gynecophoral canal in
males.
• COLOR: Greyish white.
• TESTES: Anterior (4 to 5)
• OVARIES: In posterior half
of body.
• UTERUS: Long with 20 to
30 ova.

56. • SIZE: 145 x 60 µm (large).
• SHAPE: Elongated.
• COLOR: Hyaline to light
yellow.
• OPERCULUM: Absent
• CONTENT: Shouldered
miracidium surrounded by
vitelline membrane
(double linear line).
• Terminal spine.

57. S. japonicum S. mansoni S. hematobium

58. Schistosomiasis, or bilharzia, is a parasitic disease caused by
trematode flatworms of the genus Schistosoma.
Theodor Bilharz was a German pathologist who first identified the
parasite in Egypt in 1851.

59. • Pathology and Immunology
• The 'swimmers' itch is due to physical damage to the
skin by proteases and other toxic substances
secreted by the cercaria.
• The host develops both type I and type IV
hypersensitivity reactions to schistomal secretions
and egg constituents.
• Embryonated eggs cause collagenase-mediated
damage to the vascular endothelium.
• Host immune responses, both humoral and cell
mediated, have been shown to be of some protective
value.
• IgE and eosinophil mediated cytotoxicity has been
suggested as a mechanism of killing the adult worm.

60. • This red spot will continue to
increase in size for the next 24-
30 hours. The raised, reddened
spot is now called a papule. It will
continue to itch for up to a week.
• Papules are limited to areas of
the body that get exposed to
water because cercariae can not
live out of the water.
• For some species of
schistosomes that cause
swimmer's itch, toweling off may
help; with other species, it will not
do any good because the
cercariae penetrated the skin
while the person was in the
water.

61. Schistosoma hematobium
affects the vesical and pelvic venous
plexus. It is known to cause
scarring, calcification and squamous cell
carcinoma of the bladder.
S. hematobium can affect the female
genital organs and
involvement of the cervix, uterus and
fallopian tube has been
reported (Swai et al. 2006).
Potential link between maternal
schistosomiasis and poor birth outcomes
Schistosomiasis should be considered in
the differential diagnosis of persistent
abnormal uterine bleeding,
cervical atypical lesions, infertility and
ectopic pregnancies.
In endemic areas cervical
schistosomiasis should be considered as
differential diagnosis of cancer.
Fig. 1. Cross section of fallopian
tube showing schistosoma egg
granulomas.

62. In Tanzania the main symptoms of female
genital schistosomiasis were bleeding
disorders (48%), ulcer (17%), tumor (20%),
lower abdominal pain (11%) and infertility
(7%). The majority of cases with genital
schistosomiasis were diagnosed in cervical
tissue (Britta Swai et al.)

63. Intestinal schistosomiasis: eggs in the wall of the gut

64. In urinary schistosomiasis, there is progressive damage to the bladder, ureters and kidneys. In intestinal schistosomiasis,
there is progressive enlargement of the liver and spleen, intestinal damage, and hypertension of the abdominal blood vessels.

65. Adult patient with severe hepatosplenomegaly
and ascites due to Schistosoma mansoni
Schistosomiasis-
portal hypertension

66. Paragonimus westermani
GEOGRAPHICAL DISTRIBUTION:
Asia and South America where culturally
people eat raw or undercooked
freshwater crab or crayfishes

67. Paragonimus westermani
• COMMON NAME: Lung fluke.
• PATHOGENISIS: Pulmonary lesions, fibrous tissue
capsules, pleurisy, pneumonitis.
• HABITAT: Lung.
• INTERMEDIATE HOST
• FIRST: Snail.
• SECOND: Crab or crayfish.
• RESERVOIR HOST: Piscivores (fish-eating animals).
• INFECTIVE FORM: Metacercaria.
• MODE OF INFECTION: Ingestion.
• SPECIMEN OF CHOICE: Sputum (also feces).

68. 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,
Perů, Venezuela).

69. Paragonimus westermani

70. • SIZE: 10 to 14 mm long by 3 to 5 mm wide (large).
• SHAPE: Oval body.
• COLOR: Reddish brown.
• INTESTINAL CECA: Undulating.
• TESTES: Deeply lobate and para.

71. SIZE: 95 x 55 µm (medium
to large;
SHAPE: Oval
COLOR: Golden brown
OPERCULUM: Present at
broad end.
CONTENT: Yolk mass
"differentiated," variable size
of granules in the yolk.
ABOPERCULAR
THICKENING
Paragonimus westermani

72. Paragonimiasis
• The adult parasites normally live in the lungs of the
definitive host, though ectopic parasites found in other
locations are also frequently seen, suggesting this
parasite is not well adapted to living in man
• Symptoms are mainly pleural effusion, pneumothorax
or intrapulmonary nodules with respiratory
symptoms
• Pathology of Infection may be divided into two areas:

73. Pulmonary Paragonimiasis
• Here fibrotic tissue forms a cyst
around the parasites in the lungs,
the parasites usually pairing even
though they are hermaphroditic.
• This cyst is surrounded by a
cellular infiltrate. Symptoms, which
may be severe in infections with
high worm densities, include
pleurisy, pneumothorax, a bad
cough, bronchitis, blood in the
sputum, mild anaemia and
weariness and may be confused
with tuberculosis and lung cancer.

74. Extrapulmonary Paragonimiasis
• In this case disease is caused by ectopic parasites
in aberrant locations. These may vary from
parasites encysted in the abdominal wall, to more
serious cerebral infections. Depending on the
location of these ectopic parasites symptoms will
vary.
• If in the intestinal wall there may be diarrhea and
abdominal pain.

75. Fig. 1. The left fifth finger showed an erythematous
swelling on the tip (Yun Su Sim et. al. 2010)
Fig. 2. Biopsy was taken and one larva
of P. westermani was found

76. Exceedingly rare case of Paragonimus westermani with a mass in
the pleural cavity
• Fig. 1. Chest computed tomographic scan
on admission showing right pleural
effusion and a mass under thickened
pleura of the lower lobe.
• Fig. 2. Thoracoscopic finding showing a
white mass measuring 8 cm in diameter in
the pleural cavity that partially connected
with the diaphragm and pulmonary pleura
of the right lower lobe.

77. Cerebral paragonimiasis
Cerebral involvement may occur
in many cases, with symptoms
such as visual disturbances,
• headaches,
• embolisms
• epilepsy.

79. • SIZE: 20 to 30 mm
long by 8 to 13
mm wide (very
large).
• SHAPE: Leaf-like;
prominent cone-
shaped projection
cephalic cone.
• COLOR:
Brownish.
• INTESTINAL
CECA: Branched.
• TESTES: Dendritic
and tandem.
Faciola hepatica

80. Newly excysted juvenile of Fasciola hepatica
and adults

81. SIZE: 140 x 80 µm (large).
SHAPE: "Hen's egg"; oval.
COLOR: Yellowish-brown
OPERCULUM: Present, indistinct.
The operculum can be open.
CONTENT: Eggs are unembrionated and
contain a granular material.
Faciola hepatic

82. Fasciolosis
• Blood-feeding capability of the parasites, as well as
tissue damage from migrating stages produce
symptoms.
• Up to 50% of Fasciola hepatica infections are
asymptomatic and disease may appear anywhere
from a few days to several years after infection.
• Eosinophilia is present with all infections at all
stages and can be used as a diagnostic factor in
ectopic and early stage infections when eggs may
not be present in the stool yet.

83. • When symptoms do appear, they occur in the following
patterns:
• Acute Phase is rarely seen in humans and occurs only
when a large number of metacercariae are ingested at
once. Fever, tender hepatomegaly, and abdominal pain
are the most frequent symptoms of this stage of infection
although vomiting, diarrhea, urticaria (hives), anemia,
and may all be present.
• The above characteristics of the acute phase are caused
by the migration of the F. hepatica larvae throughout
the liver parenchyma. The larvae penetrate the liver
capsule and begin to produce the above symptoms 4-7
days after ingestion.
• Migration and thus the acute phase continues for 6-8
weeks until the larvae mature and settle in the bile ducts.

84. • Chronic Phase The symptoms of chronic infection
are much more common in human populations and
include biliary cholic, abdominal pain, tender
hepatomegaly, and jaundice.
• In children, severe anemia is a common result of
infection and is the greatest source of disability
from infection in this age group. These symptoms
reflect the biliary obstruction and inflammation
caused by the presence of the large adult worms
and their metabolic waste in the bile ducts.
• Inflammation of the bile ducts eventually leads to
fibrosis and a condition called "pipestem liver", a
term describing the white appearance of the biliary
ducts after fibrosis.
• The final outcome of severe infections is portal
cirrhosis and even death.

85. • Halzoun The condition commonly known as
halzoun is a type of Fasciola hepatica infection in
which the worm settles in the pharynx.
• This occurs when an individual consumes infected
raw liver. The young adult worms then attach
themselves to the pharyngeal mucosa which
causes considerable pain, edema, and bleeding
that can interfere with respiration. The adults can
cause symptoms for up to 10 years.
• Ectopic Infection Ectopic infections through
normal transmission are infrequent but can occur
in the peritoneal cavity, intestinal wall, lungs,
subcutaneous tissue, and very rarely in other
locations.

86. Fasciola hepatica

87. • Chronic fasciolosis in goat, the liver show
severe fibrosis, mainly in the left lobe.