Schistosomes are trematode parasites that infect humans and animals. They have separate sexes unlike other trematodes. The eggs of different Schistosome species vary in shape and features. Schistosome infection occurs through skin penetration by the cercarial stage released from infected snails. Adult worms reside in the mesenteric or bladder veins depending on the species. The pathology results primarily from the host immune response to eggs that are deposited in tissues.

3. Schistosomes
• •They have one intermediate host which is
the snail (- That’s why they have restricted
geographical distribution).
• ** Various animals as dogs, cats,
rodents, pigs, horses & goats, serve
as reservoirs for S. japonicum, and
dogs for S. mekongi.

4. • They are separate sexes (which is contrary to
the other hermaphroditic ‫خنثى‬trematodes) :

5. summery

6. ** S. haematobium; Eggs
• large in urine ( in urinary bladder ) with
terminal spine at posterior end.
• looks a like the egg of S. intercalatum,,(if u
suspect between them , refer to the
geographical distribution)

8. S. japonicum; eggs :
• typically oval or subspherical , with knob
(vestigial spine) on side.
• - Differential Diagnose : it’s similar to S.
mekongi.
• - S. japonicum eggs are sometimes carried to :
(1) CNS , resulting in : headache,
disorientation, amnesia & coma. (2) heart ,
resulting in : arteriolitis & fibrosis →
enlargement & failure of Right ventricle.

10. ‫أبو‬‫ذنيبة‬

11. • - There is No vehicle of infection (( Its direct
infection )) ‫ناقل‬ ‫بدها‬ ‫ما‬ ‫المرض‬ ‫بتسبب‬ ‫نفسها‬ ‫هي‬ ‫يعني‬
• it will mature in the liver and became adults in ≈3
weeks , then reach a specific place depend on the
type : - it will reach the mesenteric if its (S.
mansoni & S. japonicum) - it will reach the
bladder venous vessels if its (S. hematobium)
where they live & ovulate for Duration of host's
life ( they live through out the host life )
Schistosomes

14. Schistosomes
• ** Pathology :
• - clinically , the Penetration of cercariae (
the initial penetreation if the intact skin )
will result in transient dermatitis
(swimmers' itch).
• - Adult worms are innocuous (not harmful)
, even that they are coating themselves
with host Ags to evade immune
responses.
• - ((very important )) Deposition of eggs , is
an inducer of pathological changes

15. Schistosomes

16. Schistosomes

17. INTESTINAL FLUKES
• Fasciolopsis buski (Giant intestinal fluke)
• - Adult :
- Lives attached to small
intestinal mucosa of
mammalian hosts
(humans & pigs).
- result in inflammation,
ulceration & abscesses.

18. Fasciolopsis buski
• Eggs :
• •Immature eggs are discharged into
intestine, passed in
• stool & become embryonated in water.

20. Fasciolopsis buski
• Human Infection ( or the infective
stage infection for human or pigs )
is by ingesting water plants (water
chestnuts) contaminated with
encysted metacercaria

21. Fasciolopsis buski
• ** Clinical Picture :
- Light infectons: epigastric pain, nausea &
diarrhea, esp. in morning.
- Heavier infections: generalized edema &
ascites.
** Treatment : Praziquantel

22. ** Heterophyes heterophyes
(Minute = very small intestinal
fluke)
• - linked to
fresh/brackish water
fish ! ‫سمك‬‫ني‬

24. Heterophyes heterophyes
• ** Clinical picture :
• - Intestinal main symptoms: diarrhea &
colicky ‫مغص‬ abdominal pain.
• Treatment : DOC is Praziquantel

25. ** Metagonimus Yokogawai

26. Liver Flukes
• a. Fasciola hepatica
• Mostly, the infection occurs from ingestion of
raw/undercooked watercress
• Adult: leaf shaped
• - Eggs : in stool , and It is notable that the eggs
are indistinguishable from those of F. Buski

27. Fasciola hepatica
• snails as the intermediate host would ingest it
• here, their sole presence would elicit
hepatomegaly hence tenderness during
palpation
• * explains the upper quadrant pain
• Medication: Praziquantel is not effective like
the case of F. Buski.
• we instead Use Triclabendazole ( very
important )

28. Fasciola hepatica
• Halzoun :
Among the notable disease from such infection of F.
Hepatica.
It is a common disease in the Middle East as some people
enjoys eating raw livers. These may contain immature
flukes of F.Hepatic , which would lead to the disease.
the (immature) flukes would attach itself at the
pharyngeal mucosa; Dysphagia
* Dsypnea
* Edema
* All pt are presented with Immune-allergic like
symptoms in the eye, nose, ears, throat (airway
obstruction)

29. b. Opisthorchis
• The old name is Clonorchis.
• - It is of three types: 1. O. Sinensis - a.k.a
Chinese liver flukes.
ingested by freshwater fish.
• 2. O. Felinus - the word 'feline' refers to cat
• 3. O. Viverini - related to dogs
cholangiosarcoma which is the tumor for connective
tissue surrounding bile duct
The proper and effective medication would be
Praziquantel

30. O. Sinensis

31. Lung Flukes
• A. Paragonimus Westermani
• (transmitted by craps
• Infects man and ( pigs , dogs).
• infection may persist up to 20 years
• The adult takes form, size and color of a coffee
bean