1. Helminthology Helminths Helminths (worms) are multicellular parasites.
They are divided into:
1- Round Worms Flat Worms
(Nemathelminths) (Platyhelminths)
Class Nematoda (Flukes) (Tape worms)
Class Trematoda Class Cestoda

2. Helminthology Questions form: Name of the parasite Intermediate host
Infective stage
Mode of transmission
Location in the host
Lab diagnosis (Diagnostic stage)
Disease

3. Class Trematoda (Flukes)

4. General Characters
1- Flat worms (no body cavity), not segmented, bilaterally flattened (except Schistosoma is cylindrical) 2- No respiratory nor vascular system. 3- Hermaphrodite (except Schistosoma)

5. 4- Body has 2 suckers for attachment: oral, ventral, (except Heterophyes has a 3 rd genital sucker) 5- Life cycle show sexual phase (definitive host) and asexual phase (intermediate host) 6- Require one or more intermediate host 7- 1st intermediate host is a snail 8- Eggs have an operculum(except Schistosoma) 9- Infective stage is encysted metacercaria (except Schistosoma: cercariae)

6. General life cycle of trematodes
1. Eggs are released from human (in feces or urine) in fresh water.
2. Eggs hatch into first larval stage (miracidial larva) that invade a snail as 1ry intermediate host.
3. All trematodes except Schistosoma sp. require a second intermediate host which is mostly a water plant or animal.
4. The second larval stage (cercarial or metacercarial larva) comes out of the intermediate host(s).
5. Humans are infected through direct penetration of cercaria (Schistosoma) or ingestion of encysted metacercaria in water plant or animal (all other trematodes).

8. 1- Intestinal Fluke Heterophyes heterophyes
Heterophyes heterophyes adult
Heterophyes heterophyes eggs
Heterophyes heterophyes snail
Heterophyes heterophyes encysted metacercaria
Heterophyes heterophyes in small intestine

9. pear shaped,
very small size, (2mm)
oral, ventral, & genital suckers
vitelline glands
2 testis, 1 ovary
simple intestinal ceaca
(L.P)

10. Snail: Pirenella conica
Eggs: small, operculated, yellowish brown, thin shell (H.P)
Snail: Pirenella conica

11. Heterophyes heterophyes adult in small intestine
Adult worm is present in intestinal villi

12. Heterophyes heterophyes encysted metacercaria in Bouri and Bolti muscles

13. Location of adult: small intestine
Intermediate host:
Primary: Pirenella conica
Secondary: Bolti and Bouri fish
Infective stage: encysted metacercaria
Mode of transmission: ingestion of raw or undercooked fish containing encysted metacercaria
Diagnosis: eggs in stool
Disease: heterophiasis

14. 2- Liver Fluke Fasciola Fasciola hepatica adult
Fasciola gigantica adult
Fasciola gigantica snail: (lymnaea cailliaudi )
Fasciola egg
Fasciola metacercaria

16. OS: oral sucker
VS: ventral sucker
OV: ovary
TE: testis
Vi: vitelline glands
UT: uterus
INC: intestinal caeca
GP: genital pore

17. Fasciola hepatica Fasciola gigantica
Less prominent shoulders, parallel margins, medial branches are T or Y shaped, larger in size
2 prominent shoulders, converging margins, simple medial branches of intestinal caeca, smaller in size

18. Snail (Lymnaea cailliaudi)
Fasciola egg: very large, operculated, yellow, thin shell

19. secondary: leaves of fresh-water plants
Location of adult: bile duct
Intermediate host :
primary : snail Lymnaea truncatula for F. hepatica and Lymnaea cailliaudi for F. gigantica
secondary: leaves of fresh-water plants
Mode of transmission: ingestion of raw water-cress containing encysted metacercariae
Infective stage: encysted metacercaria
Diagnosis: eggs in stool
Disease: Fascioliasis

20. 3- Blood Fluke Schistosoma sp.
Schistosoma mansoni male
Schistosoma mansoni female
Schistosoma mansoni male & female
Eggs of Schistosoma mansoni
Eggs of Schistosoma haematobium
Snail of Schistosoma mansoni
Snail of Schistosoma haematobium
Schistoma cercaria

21. S. mansoni
S. mansoni male: 8-10 mm, has gynaecophoric canal, dorsal surface covered with tubercle
S. mansoni female: 14 mm, taller and thinner, vitelline glands occupy 2/3 of the body
S. mansoni male & female

22. S. mansoni snail Biomphlaria alexandrina
S. mansoni egg: oval with lateral spine
Cercaria of S. mansoni: elongated head, biforked tail

23. S. haematobium
Egg: oval with terminal spine
Snail: Bulinus truncatus

24. S. mansoni S. haematobium
Location:
veins of large intestine, colon (lower mesentric vein)
Intermediate host:
Biomphalaria alexandrina
Diagnosis:
eggs in stool
Infective stage: cercariae
Mode of transmission:
direct skin penetration of cercariae during swimming
Disease:
Intestinal Bilharziasis
veins of urinary bladder (venous plexus of urinary bladder)
Bulinus truncatus
Eggs in urine
Cercariae
direct skin penetration of cercariae during swimming
Urinary Bilharziasis