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Filariasis
 

 

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    Filariasis Filariasis Presentation Transcript

    • Filarial WormsRumala MorelDept. of ParasitologyPeradeniyaY2S2
    • Teaching Learning Objectives: Name the major tissue nematodes of humans indicating theirlocation in the human body. List the major characteristics of the filarial parasites ofhumans indicating those found in Sri Lanka Name the vectors of those parasites found in Sri Lanka Outline the life cycle of a typical filarial parasite Describe the life cycle of Wuchereria bancroftiDescribe the phenomenon ‘Periodicity of microfilaria’ State the stages that cause pathogenic effects Identify stages of diagnostic importance Outline laboratory methods of visualization/identification ofparasites/products Identify points in the life cycle where preventive measuresare applicable
    • FILARIAL WORMS: Filariasis tissue nematodes adults thread like; female embryos (early first stage larvae)microfilariae (mf)• transmitted by insect vectors• adults in different habitats in body• mf in blood/ subcutaneous tissue
    • Human filarial parasites grouped according toHABITAT of the ADULT WORM in man Lymphatic filariae Subcutaneous filariae filarial infections of the body cavities& associated tissue
    • LIFE CYCLEMAN2 moults Adultsmf in blood /subcutaneous tissueINSECT VECTOR2-moultsNO multiplicationInfective larva-L3
    • Microfilaria- periodicityIn some species mf in peripheral blood onlyduring certain times during 24 h period. Non periodic Periodic - nocturnally- diurnally Sub periodic- mf present at all timesbut peak nocturnally or during daytime
    • Periodicity of microfilariaphysiological adaptation to biting habits of vectorMf bldpatency6h 12h 24h 2h 6hNocturnallyperiodicNonperiodicDiurnallyperiodicSub periodic
    • LYMPHATIC FILARIAEmosquito borneadults in lymphatics / mf in blood Wuchereria bancrofti-widespread tropics Brugia malayi- SE Asia, India Brugia timori- Timor island,other islands nearby
    • HydrocoeleLymphoedema
    • Distribution of lymphatic filariaeSub periodic W. b
    •  Dog filarial wormDirofilaria repens- zoonosis in Sri LankaFilarial infections of Man in Sri Lanka Bancroftian filariasis- W bancrofti(nocturnally periodic)
    • Wuchereria bancrofti (nocturnally periodic)High prevalence in hot,humid, tropics.associated with ‘poor’ urbanizationVector-common urban mosquitoCulex quinquefasciatusIn E Africa- vector rural-Anopheles gambiaePacific islands- diurnally sub periodicvector day biting -Aedes spp
    • life span 7-16 yrs
    • Larva developing in themosquito thoracic muscle
    • Infective larvae L3 emerging from proboscisof mosquito
    • Adults ofWuchereria bancroftiare long and threadlike.MALES (left) measureup to 40 mm longand FEMALES (right)are 80-100 mm long.
    • tail nucleiWuchereria bancrofti -mf Brugia malayi300 x10 µm 260 µmLie- graceful curves kinked (acute angles)head space- short longnuclei- countable, overlapping,tail nuclei+head space
    • Laboratory Diagnosis of Filariasis:Direct Detection of mf in bloodThick film- 10pm-2 am (20-60µl)wet mount/ stain GiemsaConcentration-•Knott’s method-1ml blood +2% formalin, centrifuge,examine deposit for mf•Membrane filtration- pore size 5µmDetection of adults in biopsy- rareDetection of Filarial Specific AbDetection of Circulating Filarial Ag.Indirect
    • A). Detection of filarial antibodies in serum Indirect immunofluorescent test- IFA/FATAntigen used - microfilariae of W bancroftisections of adult worms (cattle filariae) ELISA (enzyme linked immunosorbent assay)Disadvantage: Ab long lastingB). Detection of Circulating Filarial Ag•Antigen detection ELISA•Immunochromatographic [ICT] Card TestINDIRECT TESTS
    • Antigen detection strip (card) tests- RDTsSample origin(whole bloodserum/plasma)polyclonal Ab+ colloidal goldMabW bancroftiT Cabsorbent padtest controlRDT = Rapid Detection TestsImmunochromatographic Card Test=
    • ImmunochromatographicCard TestAg detectionELISA plate
    • ICT card testImmunochromatographic card test-detects specific circulating W bancrofti Agin serum/whole blood using monoclonal Ab IgG4 simple, no equipment required quick results <15 min no need for night blood 100% sensitive in mf +s Not quantitative (+/-)But disease severity not dependant on mf densityDisadvantage: High cost > Rs. 1600/test
    • Filariasis in Sri Lanka-1937-39: Brugia malayi predominant1947: Anti Filariasis Campaign1960’s: Brugian filariasis eradicatedcontrol of larval breedingresidual action of DDT on adultstreatment with DECBancroftian filariasis is the ONLYlymphatic filariasis in SL now
    • LF is endemicin eight of the25 districts.Confined tourbanizedcoastal belt:9.5 million(50%)populationexposedinland foci:Gampaha,WarakapolaVeyangoda
    • Global Elimination of LymphaticFilariasis• Global Programme to Eliminate Lymphatic Filariasis -WHO 1998• Global Alliance to Eliminate Lymphatic Filariasis - 2000– public-private partnership– WHO, national Ministries of Health,– Private drug companies donating albendazole &ivermectin (Mectizan®)– NGOs• 1 billion at risk population• > 120 million people are already infected• > 40 million incapacitated or disfigured
    • Bancroftian filariasis control in Sri Lankavector control:prevent mosquito breedingclear drains, cess pits, sealing of septic tankslarviciding with insecticides, larvivorous fish Selective treatment of mf + caseswith 2-week DEC (6 mg/kg) Mass chemotherapy- eradication of parasite bykilling mf and disrupting transmission- continued for4-5 yearsMorbidity control clinics – disability managementtraining
    • Culex quinquefasciatus breeding sitesDirty water in blocked drains, cess pits etc.
    • Brugia malayi - Confined to AsiaNot detected in Sri Lanka since 1962aduAdults in lymphatics of lower limbs, groin. Rare in genitalia.Mf sheathed, characteristic morphologyPre patent period- 1-3 monthsSub periodic form- SE Asia-zoonoses(monkeys,dogs & cats)B malayi- nocturnally periodicVector: Mansonia speciesFemale mosquito of Mansonia spplays eggs on the under surface ofleaves of water plantseg. Pistia, Salvinia, Eichonia
    • Subcutaneous filariasis of humansdifferent fly vectorsmf in blood / subcutaneous tissuebiting habits of vectorOnchocerca volvulus- OnchocerciasisMajor public health problem - tropical Africavector- black flies, mf – subcutaneousLoa loa- Tabanids, mf in bloodBody cavities:Mansonella spp- culicoides, mf in blood
    • Dirofilaria repens - DirofilariasisZoonotic filariasis in Sri Lankaa common subcutaneous filarial infection of dogs inSri LankaTransmitted by several species of mosquitoesAedes, Armigeres & Mansonia spp.Human disease commonCauses subcutaneous nodulesdue to granulomatous reactionto adult wormbutnot known toproduce microfilariaein humansD.repens adult
    • Cross-sections of Dirofilaria sp. from a subcutaneous nodulestained with hematoxylin and eosin (H&E).100x 200x
    • Onchocerciasis = River BlindnessSimulium (black fly)fast flowing riversRiver Volta-W Africa
    • mff causes eye lesions:blindnessIn skin: itching, depigmentationloss of elasticityAdults cause subcutaneous nodules
    • Loa loa- loasisAdults in subcutaneous tissueMf in blood- diurnally periodictransmitted by blood sucking day-biting fliesVectors: Tabanid fliesConfined to Tropical Africa where vectors arefoundMf in bloodAdult worm underthe conjunctiva- 10 mmTransient swellings-days
    • Tabanid flyadult worm underthe conjunctiva
    • Filarial worms- Wucheraria bancrofti [SRI LANKA]Brugia malayi• Subcutaneous filariae- Onchocerca volvulus [River blindness]- Loa loa- Dirofilaria repens [ZOONOSIS in SRI LANKA]• filarial infections of the body cavities& associated tissue•Lymphatic filariae