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Nematodes General Features Have elongated, cylindrical, smooth, unsegmented, flesh- colored bodies. Body is usually tapered to a pointed posterior end,

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Presentation on theme: "Nematodes General Features Have elongated, cylindrical, smooth, unsegmented, flesh- colored bodies. Body is usually tapered to a pointed posterior end,"— Presentation transcript:

1 Nematodes General Features Have elongated, cylindrical, smooth, unsegmented, flesh- colored bodies. Body is usually tapered to a pointed posterior end, and to a rounded anterior end The body is covered by a noncellular, highly resistant coating the cuticle They have complete digestive system with mouth, oesophagus, midgut and anus. All are separate sexes; the female is usually larger than the male. They are classified into 2 main categories according to their primary location: –Intestinal nematodes –Tissue nematodes (filariae)

2 Main features of Nematodes Intestinal NematodesTissue Nematodes ShapeLarge size, CylindricalElongated, Slender (slim) HabitatMost adult worms live in the intestinal tract Inhabit either lymph vessels; or skin and subcutaneous tissues DiseasesDiseases are diagnosed by identifying their characteristic eggs in stool Diseases are diagnosed by demonstrating microfilariae in blood, in tissue or tissue fluids

3 Medically important Nematodes. Intestinal NematodesTissue (Filarial worms) 1. Enterobius vermicularis I. Lymphatic filariae: 1. Wuchereria bancrofti 2. Burgia malayi 2. Ascaris lumbricoides 3. Hookworms *Ancylostoma duodenale *Necator americanus II. Cutaneous filariae: 1. Dracunculus medinensis 2. Loa loa 3. Onchocerca volvulus 4. Trichuris trichiuria 5. Trichinella spiralis

4 Comparison between 1. Enterobius vermicularis and 2. Ascaris lumbricoides I. Intestinal Nematodes

5 Female Male Enterobius vermicularis Enterobius vermicularis eggs Enterobius vermicularis egg

6 Ascaris fertilized egg. Ascaris egg containing a larva, which will be infective if ingested. Ascaris unfertilized egg. Female Male Ascaris lumbricoides

7 Enterobius vermicularisAscaris lumbricoides Name Pinworm, seat worm Ascariasis, round worm Size Female 8-13, male 2-5 mmFemale 20-35, male cm Disease Enterobiasis (oxyuriasis)Ascariasis Geographica l distribution Worldwide, most common in temperate regions and in crowded places Worldwide; high prevalence in tropical and subtropical areas with inadequate sanitation, and where human feces are used as fertilizer Infective stage Embryonated egg Mode of infection Ingestion; or autoinfection via nails scratching the perianus Ingestion of eggs in food contaminated with human feces Infection site Large intestineSmall intestine, lung

8 Enterobius vermicularisAscaris lumbricoides SymptomsPerianal Pruritis, especially at night, appendicitis, abdominal pain, *invasion of girls genital tract cause vaginitis, pelvic or peritoneal granulomas Migrating worms cause occlusion of biliary tract or oral expulsion in lung it causes inflammation with pulmonary symptoms, e.g. cough, hemoptysis Identificati on Characteristic eggs collected mornings from perianal area using transparent adhesive tape adult worm may be found in perianal area or during vaginal examination Characteristic eggs in feces, larvae identified in sputum or gastric aspirate adult worm may pass in stool. TreatmentPyrantel pamoateAlbendazole, Mebendazole, Pyrantel pamoate

9 Enterobius vermicularis

10 Ascaris lumbricoides

11 3. Hookworms Ancylostoma duodenale Old World hookworm Necator americanus New world hookworm

12 Geographical distribution Worldwide, in areas with warm, moist climate Ancylostoma duodnale: Middle East, North Africa Necator americanus: America DiseaseHookworm infection Infective stageFilariform larva Mode of transmission Filariform larvae in moist soil penetrate skin through bare feet Site of infectionSmall intestine, heart, lung Diagnostic stageEgg in feces; oval, colorless, thin- shelled, segmented Clinical findingsIron deficiency: Anemia due to loss of blood at site attachment in intestine *cardiac problems *local skin manifestations ground itch *respiratory symptoms during larval pulmonary attack

13 Hookworms

14 Laboratory diagnosis: Microscopic examination of characteristic egg in stool Treatment Albendazole, Mebendazole, Pyrantel pamoate Hookworm larva Egg of hook worm: oval or ellipsoidal shape with thin shell

15 4. Trichuris trichiuria Trichuris trichiura: a macroscopic view of a tangled mass of adults Trichuris trichiura adults in gut (preserved post mortem specimen ) Trichuris trichiuria egg a typical barrel shape with two polar plugs, that are unstained

16 Common nameWhipworm Length of adult wormFemale 20-35, male mm Geographical distribution Worldwide; high prevalence in tropical and subtropical areas with inadequate sanitation, and where human feces are used as fertilizer as Ascaris DiseaseTrichuriasis, trichocephaliasis Infective stageEmbryonated egg Mode of transmissionIngestion of eggs in food contaminated with human feces Site of infectionLarge intestine (cecum) Diagnostic stageEgg in feces; are brown, barrel-shaped with a plug at each pole ; contains a fertilized unsegmented ovum. Clinical findingsheavy infection, especially in children can cause gastro- intestinal problems (abdominal pain, diarrhea, rectal prolapsed), and possibly growth retardation Laboratory diagnosismicroscopic examination of characteristic egg in stool adult worm may be identified upon examination of rectal mucosa by proctoscopy TreatmentMebendazole; Albendazole as alternative

17 Trichuris trichiuria

18 5.Trichinella spiralis Encysted larvae of Trichinella in pressed muscle tissue. Larvae of Trichinella, freed from their cysts, typically coiled.

19 Common nameTrichinosis Length of adultMale 2.2, female 1.2 mm Geog. distributionWorldwide DiseaseTrichinillosis, trichinosis Infective stageEncysted larva Transmission modeLarvae in undercooked pork. Pigs are main reservoir Site of infectionStriated muscles Diagnostic stage Larvae in muscles and tissues Clinical findings Larvae migration in muscular tissues cause facial and periorbital oedema, rash, muscle pain, conjunctivitis Laboratory diagnosis Muscle biopsy to identify larvae in striated muscles *indication of eosinophilia *serologic tests TreatmentSteroid plus Mebendazole in severe infections *thiabendazole

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21 II. Tissue (Filarial) Nematodes a. Lymphatic Wuchereria bancrofti Brugia malayi b. Cutaneous Dracunculus medinensis Loa loa Onchocrca volvulus

22 Wuchereria bancrofti Bancroft's filaria Brugia malayi Elephantiasis Geo. Dist.Worldwide in tropical areasLimited to Asia (Malaysia) DiseaseElephantiasis, Wuchereriasis Bancroftian filariasis, lymphatic filariasis Malayan filariasis, lymphatic filariasis Mode of transmn Mosquito (Anopheles sp. or Culex sp.) Mosquito (Mansonia sp., or Aedes sp.) Inf. stageMotile microfilaria Site of infection Lymph nodes, lymphatic glands and vessels in legs, arms and genitalia (testes) Lymph nodes, lymphatic glands and vessels in legs, arms but genitalia is not affected. Clinical findings Inflammation of vessels, rupture of lymphs, fibrosis, leading to obstruction. Thickening, hypertrophy of tissues, enlargement of tissues (especially extremities and genitalia) Inflammation of vessels, rupture of lymphs, fibrosis, leading to obstruction. Thickening, hypertrophy of tissues, enlargement of tissues (especially extremities) but genitalia enlargement is not seen.

23 Life cycle of wuchereria bancrofti

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25 Diagnosis: Demonstration of microfilaria in blood molecular diagnosis using PCR Treatment: Diethylcarbamazine, Surgery in elephantiasis Wuchereria bancrofti Brugia malayi

26 b. Cutaneous Nematodes 1.Dracunculus medinensis 2.Loa loa 3.Onchocrca volvulus

27 Dracunculus medinensisLoa loaOnchocerca volvulus Guinea fire worm Eye wormBlinding worm Geog. distrib Africa, Yemen, India, South America Africa, Africa, Latin America, and Middle East LengthFemale over 100 cm, male 2 cmF: 40-70mm, m: 30-34mm F: cm, male m VectorCyclope Fly of genus Chrysops (deerfly or mango fly) Fly of genus Simulium (black fly ) Site of infectio Spread from intestinal walls to tissues and subcutaneous tissues Subcutaneous tissues, and muscles Nodules in subcutaneous tissues Disease Dracunculosis, Guinea worm dis. Loiasis, Calabar swellingOnchocerciasis, River blindness Sympto ms Urticaria, skin ulcer (the worm emerges as whitish filament in the center of a painful ulcer), rupture of worm during surgical removal an anaphylactic reaction Angioedema, swelling of various parts of body (Calabar swelling), conjunctivitis, irritation, oedema of eyelids, impaired vision Pruritis, papule dermatitis with thickening, scaling and dryness of skin (lizard skin), fibrous onchocercoma subcutaneous nodules, ocular lesion blindness Diagnos is Demonstration in local lesion or fluid discharge of adult worm (head of worm) or rhabditiform larva seen under the skin Demonstration of microfilaria in blood (since adult worm lives in subcutaneous tissue and microfilaria in blood) Examination of nodule aspirate, histopathology of skin near nodule; adult lives in subcutaneous tissue, microfilaria in subcutaneous fluid Treatm ent Diethylcarbamazine, thiobenzadole, niridazole, surgery Diethylcarbamazine for microfilaria and adult, soothing lotion for Calabar swelling Ivermectin against microfilaria, Suramin (Bayer 205, antropyl) against adult, surgery

28 The female guinea worm (Dracunculus medinensis) induces a painful blister Ruptured blister, the worm emerges as a whitish filament in the center of a painful ulcer which is often secondarily infected. Rolling of the worm over a rod 1. Dracunculus medinensis

29 2. Loa loa

30 3. Onchocerca volvulus Black flies of the genus Simulium. Nodules containing Onchocerca volvulus on the head of a man in Guatemala

31 Dracunculus medinensis

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