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
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