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Parasitology is classified into three main groups

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1 Parasitology is classified into three main groups
Protozology (proto = primitive) Study of protozoa Helminthology (Helminth = Worm) Study of helminth Entomology Study of arthropods

2 Helminths (worms) are multicellular parasites.
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

3 Class Trematoda

4 General characters Flat worms (no cavity), not segmented, bilaterally flattened (except Schistosoma is cylindrical) Hermaphrodite (except Schistosoma) Body has 2 suckers for attachment : oral, ventral, (except Heterophyes has a 3rd genital sucker.

5 General characters Life cycle show sexual phase (defenitive host) and asexual phase (intermediate host) Require one or more intermediate host 1st intermediate host is a snail. Eggs have an operculum. Infective stage is encysted metacercaria. (except Schistosoma: cercariae)

6 Snail: Pirenella conica
1. Heterophyes heterophyes Snail: Pirenella conica Eggs: small, operculated, yellowish brown, thin shell (H.P)

7 Heterophyes heterophyes cont.
Pear shaped, Very small size, (2mm) Oral,ventral, genital suckers Vitelline glands 2 testis, 1 ovary simple intestinal ceaca (L.P)

8 Heterophyes heterophyes cont.
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 fish containing encysted metacercaria. Diagnosis: Eggs in stool. Disease: Heterophiasis.

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

10 Fasciola hepatica Fasciola gigantica
Fasciola sp. cont. Fasciola hepatica Fasciola gigantica Less prominent shoulders, parallel margins, larger in size cephalic cone, 2 shoulders, converging margins,smaller in size

11 Snail (Lymnae caillaudi)
Fasciola sp. cont. Snail (Lymnae caillaudi) Fasciola egg:very large, operculated, yellow, thin shell (H.P)

12 Fasciola sp. cont. 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.

13 Schistosoma sp. a. Schistosoma mansoni Schistosoma mansoni male:
8-10 mm, has gynacophoric canal, dorsal surface covered with tubercle (4X) Schistosoma mansoni female: 14 mm, taller and thinner,vitelline glands occupy 2/3 of the body( 4X)

14 Schistosoma mansoni snail Biomphlaria alexandrina
a. Schistosoma mansoni cont. Cercaria of Schistosoma mansoni : elongated head, biforked tail (H.P) Schistosoma mansoni egg: oval with lateral spine (H.P) Schistosoma mansoni snail Biomphlaria alexandrina

15 b. Schistosoma hematobium
Egg: oval with terminal spine (H.P) Snail: Bulinus truncatus

16 Schistosoma mansoni Schistosoma hematobium Location Veins of large intestine, colon (lower mesentric vein Veins of urinary bladder (venous plexus of urinary bladder Interm. host Biomphalaria alexandrina Bulinus truncatus Diagnosis Eggs in stool Eggs in urine Infective stage Cercariae Mode of transmission Direct skin penetration of cercariae during swimming Disease: Intestinal Bilharziasis Urinary Bilharziasis

17 Helminthology Questions form: Name and sex of the parasite
Class to which the parasite belongs Location in the host Intermediate host Definitive host Infective stage Mode of transmission Lab diagnosis Disease

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