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Helminths(General Features) 1..Helminth Greek word means Worm. 2. Their outer covering which is resistant to intestinal digestion is called cuticle. 3. Their mouth is provided with teeth/cutting plates. 4. Hooks are for attachment to host. 5.Helminths do not possess complete digestive system and depend on predigested nutrients available from the host. Helminths(General Features Contd:) 6.Males are smaller than females. 7.They do not multiply in the host. 8.Oviparous/Viviparous/Ovoviviparous Classification(Worm Shape) 1..Nematodes: (Cylindrical shape,unsegmented) Ancylostoma,Entrobius,Dracunculus,Trichuri s,Ascaris lumbricoides,Trichinella spiralis 2. Trematodes: (Leaf-like called Flukes,unsegmented) Shistosomes,Fasciola hepatica 3. Cestodes: (Tape-like,segmented) T saginata, T solium, E granulosus, D latum, H nana General features of Nematodes: 1..The name nematode means threadlike. 2.Nematodes are elongated, cylindrical, unsegmented worms with tapering ends. 3.They are bilaterally symmetrical. 4.The adults vary in size from about 1mm to about 1 meter in length. General features of Nematodes(Contd:) 5.The body is covered with a tough smooth cuticle. 6.The sexes are separate. 7.Nematodes may produce eggs(oviparous),or larvae(viviparous). Some lay eggs containing larvae (ovoviviparous). General features of Nematodes(Contd:) 8.The life cycle consists of 4 larval stages and the adult form. The cuticle is shed from one stage to another. 9.The shedding of cuticle in order to acquire new growth is called Moulting. Ancylostoma duodenale(Hook Worm) Morphology: 1.Live in small intestine mostly jejunum. 2.They are reddish brown in color due to ingested blood. 3.Anterior end curved, hence name hook worm 4.Male 8-11mm in length and 0.4mm thick. 5.Female 10-13mm in length and 0.6mm thick. 6.Eggs are oval containing 4-8 segmented ovum measuring 6oµm by 40µm. Adult forms male and female Geography Ancylostoma duodenale is found in 1.Pakistan and India 2.Middle East 3.North Africa 4.Europe It infects about 1 billion people of the world(1/5 of world population is effected). Life Cycle 1.Eggs passed in feces. In sandy soil develop into rhabditiform larva in two days which is non-infectious and feed on vegetation. It is about 250µm long. 2.On 3rd or 5th day infective filariform larva develops after two moults which does not feed and wait for human host. It is about 500µm long. 3.When person walks bare-footed it penetrates the skin. Life Cycle(Contd:) 4.Then enters S/C tissue and penetrates into venules. 5.Through blood circulation reaches right side of heart and then in lungs. 6.Then it breaks out the capillaries to reach alveoli. 7.Migrates upwards, crawls over epiglottis, reaches jejunum when swallowed. Life Cycle(Contd) 8.In jejunum it matures into male or female adult after two moults. It takes about 6 weeks to become sexually mature. 9.In small intestine they attach to the intestinal wall and feed on blood. 10.After mating female produces eggs and cycle is repeated. Egg of Ancylostoma duodenale Rhabditiform larva Filariform larvae Life cycle Pathogenesis and C/F 1.Local itching where larva enters skin and if it is associated with secondary bacterial infection it is called ground itch. 2.Pneumonitis and cough. 3.Eosinophilia Pathogenesis and C/F(Contd:) 4.Iron deficiency anemia(Hypochromic microcytic anemia) 5.Epigastric pain, vomiting 6.Diarrhea,reddish/black stools 7.Hypoproteinemia 8.Dyspnea,palpitation Diagnosis 1.Presence of eggs in feces by direct microscopy. 2.Adult hook worm may be seen in feces. 3.Eosinophilia. 4.Microcytic hypochromic anemia. Egg of Ancylostoma duodenale Adult forms male and female Treatment 1.Mebendazole / Pyrantel pamoate. 2. Iron to treat iron deficiency anemia. Prevention 1.Do not defecate in places other than latrines, toilets. 2.Do not walk barefooted.