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Intestinal Nematodes Protozoa helminths Unicellular Single cell for all function Multicellular Specialized cells Amoebae: move by psudobodia. Flagellates: move by flagella. Ciliates : move by cilia Apicomplexa (sporozoa) Tissue parasites Round worms (Nematodes) cylindrical, unsegmented Flat worms 1-Trematodes: leaf-like, unsegmented. 2-Cestodes: tape-like, segmented HELMINTHS • Round worms (nematodes): Elongated, cylindrical, unsegmented. • Flat worms: -Trematodes: leaf-like, unsegmented. -Cestodes : tape-like, segmented NEMATODES Common intestinal nematode infections: • Enterobius (Oxyuris) vermicularis (Pinworm,seatworm,threadworm) • Trichuris trichiura (whipworm) • Ascaris lumbricoides (roundworm) • Ancylostoma duodenale & Necator americanus (hookworm) • Strongyloides stercoralis ENTEROBIUS VERMECULARIS Enterobius vermicularis Pathology & Clinical picture Most infections asymptomatic. Intense anal pruritus dermatitis & bacterial infection. Heavy reinfection vulvovaginitis and appendicitis. Diagnosis: scotch tape preparation to collect eggs from perianal skin microscopy Enterobius vermicularis scotch tape preparation Section of adult pinworm in appendix Enterobius eggs Trichuris trichiura (Whipworm) Trichuris trichiura Embryonated egg Unembryonated egg Pathology & Clinical picture Light infections: asymptomatic. Heavy infection: abdominal symptoms and diarrhea leading to rectal prolapse in children. Diagnosis: eggs in stools rectal prolapse Trichuris trichiura eggs Ascaris lumbricoides Ascaris lumbricoides Pathology & Clinical picture Adult worm: Light infections asymptomatic. Migrating adult worm may obstruct bile duct Heavy infections intestinal obstruction. Larvae: Loeffler's syndrome Diagnosis: eggs in stools, larvae in sputum Ascaris lumbricoides Ascaris adult Ascaris adults Embryonated egg Unembryonated Ascaris eggs Ascaris eggs Ascaris larva in lung Ascaris eggs Ascaris larva emerging from egg Hookworms Ancylostoma dudenale & Necator americanus Hookworms Pathology & Clinical picture Low worm burden: no symptoms. Moderate to heavy burden: epigastric pain vomiting, hemorrhagic enteritis, severe anemia, protein loss hypoproteinaemia and oedema. Diagnosis: eggs in stools Hookworms Hookworms eggs Hookworms Hookworms Strongyloides stercoralis Strongyloides stercoralis Pathology & Clinical picture Cutaneous: little or no reaction on penetration. Intestinal: inflammation of upper small intestine mucosa, diarrhea, upper abdominal pain. Disseminated strongyloidiasis: in patient with immunodeficiency-invasion of liver lungs and brain. Diagnosis: Identification of larvae in stools, duodenal aspirate or tissues. Drug Treatment for intestinal nematodes The most commonly drugs used (antihelmintic) for intestinal nematodes are: • Albendazole • Mebendazole