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Tissue Nematodes II BPT. 08/04/09 Classification – Tissue Nematodes LymphaticWuchereria bancrofti Brugia malayi SubcutaneousLoa loa (african eye worm)

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Presentation on theme: "Tissue Nematodes II BPT. 08/04/09 Classification – Tissue Nematodes LymphaticWuchereria bancrofti Brugia malayi SubcutaneousLoa loa (african eye worm)"— Presentation transcript:

1 Tissue Nematodes II BPT

2 08/04/09 Classification – Tissue Nematodes LymphaticWuchereria bancrofti Brugia malayi SubcutaneousLoa loa (african eye worm) Onchocerca volvulus (blinding filaria) Dracunculus medinensis (thread worm) Brugia timori ConjunctivaLoa loa

3 08/04/09 Wuchereria bancrofti (Filarial worm) Definitive hostMan Intermediate hostFemale Culex, Aedes or Anopheles mosquito Infective formThird stage larva Mode of transmissionInoculation – bite of mosquito Site of localizationLymphatics / lymph nodes of man

4 08/04/09 Life cycle

5 08/04/09 Clinical features Infection - Wuchereriasis/ Lymphatic filarisis/ Bancroftian filariasis Pathogenic states are produced only by adult worm (living/ dead) – classical filariasis Occult filariasis – lesions produced by microfilaria Clinical states in classical filariasis can be classified as: Asymptomatic ( in endemic areas) Inflammatory – lymphadenitis, lymphangitis, fever, lymphoedema Obstructive – elephantiasis, lymphangiovarix, chyluria, hydrocele Tropical pulmonary eosinophilia

6 08/04/09 Obstructive stage Lymphatic obstruction – occurs with the death of worms Causes of obstruction – Blocking of lumen by dead worms Excessive proliferation & thickening of walls of lymphatic vessels Fibrosis of lymphatic vessels

7 08/04/09 Consequences of Lymphatic Obstruction Elephantiasis of organs like leg, scrotum, penis, vagina, breast, arm etc – fibrotic thickening of skin & subcutaneous tissue Lymphangiovarix – dilatation of afferent lymphatics. Rupture of Lymphangiovarix into urinary tract – chyluria Hydrocele

8 08/04/09 Lymphatic filariasis

9 08/04/09 chyluria

10 08/04/09 Classical v/s Occult filariasis Classical filariasisOccult filariasis CauseDeveloping worms & adultsMicrofilariae Basic lesionsAcute inflammation followed by an epitheloid granuloma surrounding the adult worm & a fibrous scar An eosinophilic granuloma (hypersensitivity reaction) Organs involvedLymphatic systemLymphatic system, lungs, liver & spleen MicrofilariaPresent in BloodPresent in affected tissues not in blood Therapeutic response No response to any drugResponds to microfilaricidal drug, DEC.

11 08/04/09 Laboratory diagnosis Specimen - blood collected at night, preferably capillary blood from ear lobes, chylous urine, hydrocele fluid, exudate from lymphangiovarix Microscopic examination – wet mount or stained with giemsa: sheathed microfilaria with no nuclei at tail tip

12 08/04/09 Laboratory diagnosis Concentration techniques – for capillary blood, venous blood (Knott’s technique) DEC provocation test – 100 mg of DEC orally, examine peripheral blood smear after 30 to 45 minutes Serology – using non specific Ags 1. Passive hemagglutination test 2. Fluoresecent ab test 3. ELISA

13 08/04/09 Treatment DEC (Diethylcarbamazine) – microfilaricidal: 6mg/ kg/day for 2-3 weeks Elevation of the affected limbs, use of elastic bandages & local foot care – reduces symptoms of lymphatic obstruction Surgical treatment of hydrocele Prevention Destruction of mosquitoes Protection against mosquito bites Treatment of carriers

14 08/04/09 Brugia sps Two species infect humans : B.malayi & B.timori Causes lymphatic filariasis Transmitted by Mansonia & Anopheles species of mosquitoes Life cycle, pathogenesis, clinical features, diagnosis & treatment – similar to W. bancrofti, with a following differences Children commonly affected Rapid development of signs & symptoms Elephantiasis affect lower extremities Chyluria & hydrocele rare

15 08/04/09 Onchocerca volvulus Definitive hostMan Intermediate hostBlack flies (simulium) Infective form Larva Mode of transmissionInoculation Site of localizationSubcutaneous tissue, dermis & eye (Blinding filaria – 2 nd most common cause of infectious blindness)

16 08/04/09 Clinical features Incubation period - 10 to 12 months Eosinophilia and urticaria. Nodular and erythematous lesions (Onchocercomata) in the skin and subcutaneous tissue Photophobia, lacrimation, keratitis and blindness – due to trapping of microfilaria in the cornea, choroid, iris and anterior chambers.

17 08/04/09

18 Diagnosis & Treatment Nodular biopsy – adult worm Skin snip – unsheathed microfilaria with no nuclei Treatment – Ivermectin, surgical removal, DEC in non ocular onchocercosis

19 08/04/09

20 Loa loa Definitive hostMan Intermediate hostChrysops (deer fly) Infective formLarva Mode of transmissionInoculation Site of localizationSubcutaneous & deep connective tissue (African eye worm)

21 08/04/09 Clinical features Subcutaneous swelling – Calabar or fugitive swelling, measuring 5 to 10 cm, marked by erythema and angioedema, usually in the extremities Migrating worm in subconjunctival tissue

22 08/04/09 Diagnosis & Treatment Peripheral blood smear - Sheathed microfilaria with nuclei upto rounded tail tip Isolation of worms from the conjunctiva or subcutaneous biopsy Treatment - Ivermectin, surgical removal, DEC (effective against adult & microfilaria)

23 08/04/09 Dracunculus medinensis Adult wormsMale 2 to 4 cm Female 70 –120 cms, viviparous Infective formLarva inside Cyclops Mode of transmissionIngestion of water contaminated with cyclops Site of localizationSubcutaneous tissue (Guinea Worm) Human Intermediate host Definitive host Cyclops

24 08/04/09

25 Clinical Features Disease – Dracunculosis Clinical features develop an year after infection following the migration of worm to the subcutaneous tissue of the leg Blister formation – rupture of blister when in contact with water - ulceration – release of larvae by adult female worm Secondary bacterial infection of ulcer

26 08/04/09 Diagnosis & Treatment Detection of adult worm – when it appears at the surface of skin Detection of larva – in milky fluid released by worm on exposure to water Radiology – calcified worm in deeper tissues Treatment – 1. Thiabendazole/ Metronodazole – symptomatic relief, easy removal of worm 2. Gradual extraction of worm by winding of a few cms on a matchstick per day, over 3 to 4 weeks 3. Surgical excision

27 08/04/09 Prevention Provision of safe water supply Education to discourage people from entering water source Filtering water through a double folded cloth Boiling water before drinking Discouraging the use of step wells


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