Presentation on theme: "Nematodes General Features"— 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 endThe 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 nematodesTissue nematodes (filariae)
2 Main features of Nematodes Intestinal NematodesTissue NematodesShapeLarge size, CylindricalElongated, Slender (slim)HabitatMost adult worms live in the intestinal tractInhabit either lymph vessels; or skin and subcutaneous tissuesDiseasesDiseases are diagnosed by identifying their characteristic eggs in stoolDiseases are diagnosed by demonstrating microfilariae in blood, in tissue or tissue fluids
6 Ascaris lumbricoides Female Male Ascaris unfertilized egg.Ascaris egg containing a larva, which will be infective if ingested.Ascaris fertilized egg.
7 Enterobius vermicularis Geographical distribution Ascaris lumbricoidesNamePinworm, seat wormAscariasis, round wormSizeFemale 8-13 , male 2-5 mmFemale 20-35, male cmDiseaseEnterobiasis (oxyuriasis)AscariasisGeographical distributionWorldwide, most common in temperate regions and in crowded placesWorldwide; high prevalence in tropical and subtropical areas with inadequate sanitation, and where human feces are used as fertilizerInfective stageEmbryonated eggMode of infectionIngestion; or autoinfection via nails scratching the perianusIngestion of eggs in food contaminated with human fecesInfection siteLarge intestineSmall intestine, lung
8 Enterobius vermicularis Ascaris lumbricoides SymptomsPerianal Pruritis, especially at night, appendicitis, abdominal pain,*invasion of girls’ genital tract cause vaginitis, pelvic or peritoneal granulomasMigrating worms cause occlusion of biliary tract or oral expulsion in lung it causes inflammation with pulmonary symptoms, e.g. cough, hemoptysisIdentificationCharacteristic eggs collected mornings from perianal area using transparent adhesive tape adult worm may be found in perianal area or during vaginal examinationCharacteristic eggs in feces, larvae identified in sputum or gastric aspirate adult worm may pass in stool.TreatmentPyrantel pamoateAlbendazole, Mebendazole, Pyrantel pamoate
11 3. HookwormsAncylostoma duodenale Old World hookworm Necator americanus New world hookworm
12 Geographical distribution Worldwide, in areas with warm, moist climateAncylostoma duodnale: Middle East, North AfricaNecator americanus: AmericaDiseaseHookworm infectionInfective stageFilariform larvaMode of transmissionFilariform larvae in moist soil penetrate skin through bare feetSite of infectionSmall intestine, heart, lungDiagnostic stageEgg in feces; oval, colorless, thin- shelled, segmentedClinical 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
14 oval or ellipsoidal shape TreatmentAlbendazole, Mebendazole, Pyrantel pamoateLaboratory diagnosis:Microscopic examination of characteristic egg in stoolEgg of hook worm:oval or ellipsoidal shapewith thin shellHookworm larva
15 Trichuris trichiura adults in gut (preserved post mortem specimen) 4. Trichuris trichiuriaTrichuris trichiura adults in gut (preserved post mortem specimen)Trichuris trichiura: a macroscopic view of a tangled mass of adultsTrichuris trichiuria egg a typical barrel shape with two polar plugs, that are unstained
16 Common nameWhipwormLength of adult wormFemale 20-35, male mmGeographical distributionWorldwide; high prevalence in tropical and subtropical areas with inadequate sanitation, and where human feces are used as fertilizer as AscarisDiseaseTrichuriasis, trichocephaliasisInfective stageEmbryonated eggMode of transmissionIngestion of eggs in food contaminated with human fecesSite 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 retardationLaboratory diagnosismicroscopic examination of characteristic egg in stool adult worm may be identified upon examination of rectal mucosa by proctoscopyTreatmentMebendazole; Albendazole as alternative
18 5.Trichinella spiralisEncysted larvae of Trichinella in pressed muscle tissue. Larvae of Trichinella, freed from their cysts, typically coiled.
19 Common nameTrichinosisLength of adultMale 2.2, female 1.2 mmGeog. distributionWorldwideDiseaseTrichinillosis, trichinosisInfective stageEncysted larvaTransmission modeLarvae in undercooked pork. Pigs are main reservoirSite of infectionStriated musclesDiagnostic stageLarvae in muscles and tissuesClinical findingsLarvae migration in muscular tissues cause facial and periorbital oedema, rash, muscle pain, conjunctivitisLaboratory diagnosisMuscle biopsy to identify larvae in striated muscles *indication of eosinophilia*serologic testsTreatmentSteroid plus Mebendazole in severe infections *thiabendazole
21 II. Tissue (Filarial) Nematodes a. LymphaticWuchereria bancroftiBrugia malayib. CutaneousDracunculus medinensisLoa loaOnchocrca volvulus
22 Wuchereria bancrofti Brugia malayi Elephantiasis Bancroft's filaria Geo. Dist.Worldwide in tropical areasLimited to Asia (Malaysia)DiseaseElephantiasis, Wuchereriasis Bancroftian filariasis, lymphatic filariasisMalayan filariasis,lymphatic filariasisMode of transmnMosquito (Anopheles sp. or Culex sp.)Mosquito (Mansonia sp.,or Aedes sp.)Inf. stageMotile microfilariaSite of infectionLymph 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 findingsInflammation 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.
25 Treatment: Diethylcarbamazine, Surgery in elephantiasis Diagnosis: Demonstration of microfilaria in blood molecular diagnosis using PCRWuchereria bancroftiBrugia malayiTreatment: Diethylcarbamazine,Surgery in elephantiasis
26 b. Cutaneous Nematodes Dracunculus medinensis Loa loa Onchocrca volvulus
27 Dracunculus medinensis Loa loa Onchocerca volvulus Guinea fire wormEye wormBlinding wormGeog. distribAfrica, Yemen, India, South AmericaAfrica,Africa, Latin America, and Middle EastLengthFemale over 100 cm, male 2 cmF: 40-70mm, m: 30-34mmF: cm, male mVectorCyclopeFly of genus Chrysops (deerfly or mango fly)Fly of genus Simulium (black fly )Site of infectioSpread from intestinal walls to tissues and subcutaneous tissuesSubcutaneous tissues, and musclesNodules in subcutaneous tissuesDiseaseDracunculosis, Guinea worm dis.Loiasis, Calabar swellingOnchocerciasis, River blindnessSymptomsUrticaria, skin ulcer (the worm emerges as whitish filament in the center of a painful ulcer), rupture of worm during surgical removalan anaphylactic reactionAngioedema, swelling of various parts of body (Calabar swelling), conjunctivitis, irritation, oedema of eyelids, impaired visionPruritis, papule dermatitis with thickening, scaling and dryness of skin (lizard skin), fibrous onchocercoma subcutaneous nodules, ocular lesion blindnessDiagnosisDemonstration in local lesion or fluid discharge of adult worm (head of worm) or rhabditiform larva seen under the skinDemonstration 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 fluidTreatmentDiethylcarbamazine, thiobenzadole, niridazole, surgeryDiethylcarbamazine for microfilaria and adult, soothing lotion for Calabar swellingIvermectin against microfilaria, Suramin (Bayer 205, antropyl) against adult, surgery
28 1. Dracunculus medinensis The female guinea worm (Dracunculus medinensis) induces a painful blisterRuptured 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