Helminthes

Classification of some medically important verms(worms) Common Name Scientific name Phylum :Platyhelminthes a-Class : Cestoda b -Class: Trematoda Tape worm Flukes Taenia , Echinococcus Fasciola,Schistosoma , Clonorchis Phylum: Aschelminthes Class: Nematoda Round worms Ancylostoma ( hooks worm ) , Ascaris (Round worm ) , Enterobius ( pin worm )

Phylum :Platyhelminthes a-Class: Cestoda General – characters of Cestodes: 1. Flattened, ribbon-shaped and segmented 2. Differ in size (few mms to several meters) 3. Covered with protective cuticle 4. The body has Scolex with organs of fixation e.g. suckers, hooks, Neck and Strobila: consists of segments (proglottids) 5. No digestive system 6. Excretion by flame cells 7. Genital system: hermaphrodite, each segment contains usually one set of male and female organs. 8. Habitat as regards man

a.Intestinal cestodes: One: Taenia saginata (The Beef Tapeworm) Disease:Taeniasis , Beef tape worm infection Habitat :upper jejunum Diagnosis: Microscopically be finding the eggs with hexacanth embryo or proglottids. Treatment:Praziquantel

Two: Taenia solium (The Pork Tapeworm) Disease: Taeniasis , Pork tape worm infection Habitat: Upper jejunum. Diagnosis: Microscopically be finding the eggs with hexacanth embryo or proglottids Treatment: Praziquantel

Overy in Taenia

Egg of Taenia spp.

b. Extra - intestinal cestodes ( tissue cestodes ): Echinococcus granulosus Disease :Echinococcosis , hydatid disease , hydatid cyst. Morphology: This is the smallest of all tapeworms (3 to 9 mm long) with only 3 proglottids. ( eggs is similar to those in Taenia = eggs with hexacanth embryo = Oncosphere)

Diagnosis : -Clinical symptoms -Pulmonary cysts can be visualized by using x-rays. - ELISA or indirect hemagglutination test. Treatment: -Treatment involves surgical removal of cyst or inactivation of hydatid sand by injecting the cyst with 10% formalin and its removal within few (4-5) minutes. -Prazequantel effective in many cases, Albendazole, in high doses, is an alternative.

Phylum :Platyhelminthes b –Class: Trematoda(Flukes) General characters: 1. Flattened dorsoventrally 2. Bilaterally symmetrical unsegmented 3. No body cavity 4. Suckers usually two 5. Alimentary canal: blind tube without anus 6. Excretory system: flame cells and collecting tubes 7. Genital system: hermaphrodite except schistosomes

Hepatic fluke: a. Fasciola hepatica b. Clonorchis sinensis Intestinal flukes : Heterophyes heterophyes Pulmonary flukes: Paragonimus westermani Blood flukes : Schistosoma spp.

Blood flukes : Male Schistosoma spp. General: 1.Shorter and broader than the female 2.Two suckers

Female Schistosoma spp. Longer and thinner than the male Cylindrical Suckers: poorly developed

Phylum: Aschelminthes Class: Nematoda ( Round Worms): General characters: 1. Elongated, cylindrical, round in cross - section,unsegmented 2. Size: varies from less than one mm to one meter 3. Covered with protective cuticle 4. Digestive system: simple tube 5. Separate sexes Male: Smaller in size than the female with curved posterior end Female: Larger in size with straight posterior end.

a. Intestinal nematodes 1. Ascaris lumbricoides 2. Enterobius vermiculares 3. Trichuris trichiurs 4. Hookworms b. Tissue nematodes: 1. Trichinella spiralis 2 Filariae

Ascaris lumbricoides: Female Ascaris lumbricoides Elongated, cylindrical, unsegmented, pink or creamy in colour with tapering ends Size: 20 - 35 x 0.5 cm Posterior end: straight Male Ascaris lumbricoides Resembles the female but : smaller in size 15 – 25 x 0.4 cm Posterior end : curved ventrally

Ancylostoma duocenale (hook worms): Ancylostoma duocenale female: Size: 1,2 cm in length Ancylostoma duodenale male: -Resembles the female except: Slightly smaller in size 1.0 cm

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