Parasitology
Lab # 2- Helminthology
Helminths
Helminths (worms) are multicellular parasites.
1- Flat Worms
(Platyhelminths)
(Flukes)
(Tape worms)
Class Trematoda
Class Cestoda
2- Round
Worms
(Nemathelminths)
Class
Nematoda
Class Trematoda
(Flukes)
Questions form
 Name of the parasite
 Intermediate host
 Infective stage
 Mode of transmission
 Location in the host
 Lab diagnosis (Diagnostic stage)
 Disease
General Characters
Adult worm
• Flat (no body cavity), not segmented,
bilaterally flattened (except
Schistosoma is cylindrical).
• No respiratory nor vascular system.
• Hermaphrodite (except
Schistosoma).
• Body has 2 suckers for attachment:
oral, ventral, (except Heterophyes
has a 3rd genital sucker).
General Characters
Host
• Show sexual phase (definitive host)
and asexual phase (intermediate host)
• Require one or more intermediate
host, 1st intermediate host is a snail
Eggs
• Have an operculum (except
Schistosoma)
Infective stage
• Encysted metacercaria (except
Schistosoma: cercariae)
General life cycle of class Trematoda
Animal
or Plant
Classification of Class Trematoda
1- Intestinal
Fluke
Heterophyes
heterophyes
2- Liver
Fluke
Fasciola spp
3- Blood
Fluke
Schistosoma spp
1- Intestinal Fluke
Heterophyes heterophyes
Infective Stage
Definitive Host
2ry Intermediate Host
1st Intermediate Host
Diagnostic Stage
1- Intestinal Fluke
Heterophyes heterophyes
Location of adult in the
body
Intermediate host
Infective stage
Mode of transmission
Lab Diagnosis
(Diagnostic stage )
Disease caused by the
worm
• Small intestine.
• Primary: Pirenella conica.
• Secondary: Bolti and Bouri fish.
• Encysted metacercaria.
• Ingestion of raw or udercooked fish
containing encysted metacercaria.
• Eggs in stool.
• Heterophiasis.
1- Intestinal Fluke
Heterophyes heterophyes
Adult worm :
Pear shaped.
Very small size (2mm).
Has oral, ventral, & genital
suckers.
Vitelline glands.
2 testis, 1 ovary.
(L.P)
1- Intestinal Fluke
Heterophyes heterophyes
Eggs:
Small, operculated, yellowish
brown, thin shell (H.P).
Snail:
Pirenella conica.
1- Intestinal Fluke
Heterophyes heterophyes
Intestinal villi
Heterophyes heterophyes
adult in small intestine.
Adult worm
Adult worm is attached to
intestinal villi (L.P).
1- Intestinal Fluke
Heterophyes heterophyes
Encysted metacercaria
Heterophyes heterophyes
encysted metacercara in Bouri
and Bolti fish muscles (L.P).
2- Liver Fluke
Fasciola spp
Infective Stage
2ry Intermediate Host
Definitive Host
1ry Intermediate Host
Diagnostic Stage
2- Liver Fluke
Fasciola spp
Location of adult in the
body
• Bile duct.
• Primary : Lymnaea truncatula (F. hepatica)
Intermediate host
Infective stage
Mode of transmission
Lymnaea cailliaudi (F. gigantica).
• Secondary: leaves of fresh-water plants.
• Encysted metacercaria.
• Ingestion of raw water-plant
containing encysted metacercaria.
Lab Diagnosis
(Diagnostic stage )
• Eggs in stool.
Disease caused by the
worm
• Fascioliasis.
2- Liver Fluke
Fasciola hepatica Fasciola gigantica
-2 prominent
shoulders
-Less
prominent
shoulders
-Converging
margins
-Parallel
margins
-Smaller in size
(Magnifier)
-Larger in size
(Magnifier(
2- Liver Fluke
Fasciola spp
Eggs:
very large, operculated, yellow,
thin shell (H.P)
Snail:
Lymnaea cailliaudi
Fasciola redia (4X)
3- Blood Fluke (Schistosoma spp)
Infective Stage
Definitive Host
Intermediate Host
Diagnostic Stage
3- Blood Fluke (Schistosoma spp.)
S. mansoni
S. haematobium
 Veins
Veinsofofurinary
urinary
• Veins of large intestine,
Location of adult in Veins of large intestine
bladder(venous
(venousplexus
colon
(lower
mesentric bladder
colon
(lower
mesentric
the body
plexus of urinary
vein)
vein)
of
urinary bladder)
bladder)
• Biomphalaria
alexandrina
alexandrina
 Bulinus
Bulinustruncatus
truncatus
Intermediate host Biomphalaria
Infective stage
Mode of
transmission
Lab Diagnosis
(Diagnostic stage )
Disease
•
Cercariae
Cercariae
 Cercariae
Direct skin penetration of cercariae during
• Direct skin penetration of cercariae
swimming
during swimming
Eggs in stool
• Eggs in stool
Intestinal Bilharziasis
Eggs in urine
 Eggs in urine
Urinary Bilharziasis
• Intestinal Bilharziasis
 Urinary Bilharziasis
Schistosoma spp.
Adult male:
8-10 mm, has gynaecophoric canal.
(Magnifier)
Adult female:
14 mm, taller and thinner, vitelline
glands occupy 2/3 of the body
.(Magnifier)
Schistosoma spp.
Adult male & female
(Magnifier)
Cercaria
(H.P)
Schistosoma mansoni
Eggs:
Oval with lateral spine (H.P)
Snail:
Biomphlaria alexandrina
Schistosoma haematobium
Eggs:
Oval with terminal spine (Picture)
Snail:
Bulinus truncatus