Malaria

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Malaria

  1. 1. 1Introduction to ProtozoaPlasmodiumRumala MorelDepartment of ParasitologyUniversity of PeradeniyaY2S2
  2. 2. 2protozoans – unicellular, eukaryotic(1)AMOEBAETrophozoites & Cyst(growing stage)pseudopodia(false feet)(3) CILIATESBalantidium coli- cilia(2) FLAGELLATESGiardia lambliaflagella
  3. 3. 3(4).Apicomplexa= SPOROZOANo organelle formotility(5). MICROSPORIDIAspore-formingPlasmodium Coccidia
  4. 4. Plasmodium species: Objectives• List the human malarial parasites indicating thespecies found in Sri Lanka• Describe the life cycle (LC)• Identify stages that are useful in diagnosis• Evaluate methods of laboratory diagnosis• Identify points in the LC where preventivemeasures are applicable4
  5. 5. 5MALARIAMal-aria (bad air)Very importanttropical disease200 millioninfected1 milliondeaths/year –African childrenNot only in Man.Mammals, reptiles, birds have their own malarialparasites
  6. 6. 65 Plasmodium spp. causing HUMAN MALARIA3.P.malariaeband form1. P.falciparumsmall rings2. P.vivaxlarge rings & schizonts4.P.ovalered cell has oval shapeFound in SL Not in SLCommonSpeciesworldwide5. P.knowlesiMonkey parasite.Human diseaseSouth-East Asia
  7. 7. 7Exo-erythrocytic phase
  8. 8. 8Life cycle- 2 hostsMAN & MOSQUITO (Anopheline female)Asexual- SCHIZOGONY in MANExo / pre - erythrocytic (liver) phaseSporozoites - schizonts merozoitesErythrocytic cycleTrophozoites schizonts merozoitesSexual- SPOROGONY in MOSQUITOgametocytes-gametes-zygote-oocystsporozoites
  9. 9. 9Liver phase= Exo Erythrocytic PhasesporozoitesSCHIZOGONYRBCMEROZOITESHepaticschizont
  10. 10. 10HYPNOZOITESSporozoitesExo ErythrocyticschizontsHypnozoites =dormant forms in liverin P.vivax & P.ovale
  11. 11. 11Plasmodium vivax- Vivax MalariaEarlier called ‘benign tertian malaria’World wide highest in Asia.Africa: Pf higherWest Africa – no Pvbecause NO Duffy Blood Group Antigen)Liver cycle- av. 8 days; hypnozoites ++Erythrocytic cycle: reticulocytes preferredParasitaemia less than 2%
  12. 12. 12ERYTHOCYTIC CYCLE - P vivaxTrophozoitesrings-amoeboid-compact-Schizonts-early/late - 24-48hGametocytesfemale & maleRbc: enlargedSchuffner’s stippling(fine, numerous, pink-red)12-24 merozoites 6 h16 h24 h&
  13. 13. 13
  14. 14. 14P falciparum: FALCIPARUM MALARIAearlier called malignant tertian malariaSevere complicated disease - fatalErythrocytic stages:Rings -multiple infection commonfine, hair –like rings(1/5thrbc)nucleus single/ fragmented (ear phone)marginal forms (accole/applique)Red Blood Cell -NOT ENLARGEDMaurer’s clefts (few, coarse, pink-red)Black malaria pigment
  15. 15. 15P.falciparum – high parasitaemia
  16. 16. 16late trophozoite 24h -compact, pigment blackSchizogony in capillaries of internalorgans - SEQUESTRATIONSchizonts 24-48hMerozoites 8-24Gametocytes- late (10 days)persists- 4 monthsCrescent shapeFemale & MaleP falciparum- No amoeboidor schizontsin peripheralblood
  17. 17. 17Infectedcells‘sticky’attach touninfectedcellsP falciparum - Rosetting of red cells-
  18. 18. 18Plasmadium malariae - quartern malariaMature rbc preferred.Trophozoites: ringsband-formpigment dark brownRbc: not enlarged; Zeimann’s stippling (v fine)SCHIZOGONY- 72 hSchizont: 6-12 merozoites(daisy head)Gametocytes: Similar to vivax but rbc not enlarged
  19. 19. 19Plasmodium ovale- ovale malariaConfined to Africa. Common in West Africa(P.vivax absent – Duffy blood gp Ag absent)Parasitized red cells appear ovalparasite ‘vivax -like’
  20. 20. 205thHuman Malaria ParasitePlasmodium knowlesiRapidly multiply –Quotidian 24hErythrocytic cycleEarly Trophozoites:small rings similar toP.falciparumLate Trophozoites :band-forms likeP.malariae
  21. 21. 21P. knowlesi – late trophozoitesBand forms like P.malariae
  22. 22. 22AnophelesculicifaciesMalaria vector in SL
  23. 23. 23SPOROGONYGametocytes escape from rbc (in mosquito gut)mature into gametesFemale- macrogameteMale- 6-8 microgametes by exflagellationFertilization - zygote (Ookinete)Motile -penetrates gut wall
  24. 24. 24Sporogony
  25. 25. 25Oocysts on mosquito gut wall
  26. 26. 26Formation of oocyst & sporozoitesSporozoites- 14 µ mDuration of sporogony in mosquito•Temperature•Humidity•Mosquito species•Parasite speciesPv,Pf10-12 dPm15-20 doocyst
  27. 27. 27FEVER with chills & rigorsPalpableSPLEENANAEMIA – Falciparum malariaSevere anaemia = leading causeof death in children
  28. 28. 28Severe falciparummalaria3yr old cerebral malaria& opisthotonosDysconjugate (asymmetric)gaze in comatose Gambianchild with cerebral malaria.
  29. 29. 29Malaria - Laboratory diagnosis2 Main Methods :(1) Microscopy – thin & thick blood film x 3(2) Antigen detection= detection of parasite derived productsproteins or enzymes(3) PCR – only for research(4) Antibody detection – screen blood donorsin non-endemic countries
  30. 30. 30Microscopy – identify parasiteThin & Thick film x3 Consecutive daysGOLD STANDARDTHICK FILM(3-5 µl)Very SensitiveLimit of detection 10-20 p/µlCan quantify against WBCsTHIN FILM(1µl)Accurate speciesidentification
  31. 31. 31Falciparum malaria - peripheral parasitaemiacould underestimate the total parasite burdenThe parasites causing the clinical symptoms areSEQUESTERED in the capillaries of deep organs- In microvascular circulationIn synchronous cycles:peripheral parasitaemia could be (-)veRepeat blood films daily – 3 consecutive days
  32. 32. 32Pf schizonts rare in peripheral blood
  33. 33. 33
  34. 34. 34
  35. 35. 35P. falciparum – thin ringsThin blood smear Thick blood smear
  36. 36. 36Disadvantages1.Need trained experienced personnel2.Can’t do in fieldMicroscopyAdvantages1.Less costly2.High sensitivity3.Can quantify
  37. 37. 37(2). ANTIGEN DETECTIONRAPID DIAGNOSTIC TESTS [RDTs]Dipstick/card methods2. Pf only DetectsHistidine Rich Protein = pf HRP2in plasma, urine+ve for 3 weeks after parasites killed.Not suitable to assess drug resistance1. Most useful commercial tests detectingPf + PvDetectsparasite Lactate dehydrogenase ( pLDH)depends on LIVE parasitesCAN USE TO TEST DRUG RESISTANCE
  38. 38. 2. RDTs – sensitivity is low(won’t detect below 100 – 200 parasites/μl)38ANTIGEN DETECTIONRAPID DIAGNOSTIC TESTS [RDTs]WHO malaria RDT performance evaluation - Round 21. High costDisadvantagesAdvantages1.Easy to do in field2.Don’t need trained persons
  39. 39. Prevention & Control of Malaria40Interrupt transmission @ different stages1. MAN3. PARASITE2. VECTORACBAA
  40. 40. 41A.Prevent Man-Vector Contact &B.Reduce Vector Densitymost useful strategies Insecticide Treated Nets [ITN] Insecticide Residual Spraying [IRS]Prevention & Control of MalariaC. Reduce Parasite PopulationEarly detection & treatment of patients
  41. 41. Prevention & Control of Malaria in SLMinistry of Health – Anti Malaria CampaignELIMINATION of Malaria transmission in SL by 201542200,000 cases in 200023 in 2012(99.99% reduction)2012 lowest number ofmalaria cases since1963Dramatic reduction of microscopically confirmed case loadhttp://www.malariacampaign.gov.lk
  42. 42. 43SL – MalariaControl MapPreviouslyMinistry of HealthAnti Malaria CampaignGoal -ELIMINATIONof malaria transmissionin SL by 2015Highest no. of casesKilinochchiMullaitivuVavuniyaHambantotaMoneragala
  43. 43. Sri Lanka Malaria transmissionHigh risk groupsOCCUPATIONS• construction workers working inrehabilitation projects in North East• persons engaged in “slash & burn” typecultivations• illegal gemming in dry zone44Traveller’s malaria -increased travel tomalarial areas of theworld
  44. 44. ReferencesWebsites• World health Organization: WHO - www.who.int/• Centers for Disease Control and Prevention (cdc)website : www.cdc.gov/Books1. Manson’s Tropical Diseases – 22ndEd2. Worms & Human Disease – Ralph Muller & DerekWakelinAtlases• Color Atlas of Tropical Medicine and Parasitology. WallacePeters, Herbert M. Gilles.

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