Protozology 1. ( Amoebas., and Ciliate.)

Protozoa are microscopic, one-celled organisms that can be free-living or parasitic in nature. They are able to multiply in humans, which contributes to their survival and also permits serious infections to develop from just a single organism.

1. Medical Parasitology
Huda AlislamTalab
B.Sc., M.Sc. Medical Parasitology
University of Medical Sciences and Technology (UMST)

2. MedicalParasitologyisthesciencedealingwithparasites
thatinfectmanandcausingdisease,hostresponse,
diagnosis,preventionandcontrol.
Medicalparasitologyisgenerallyclassifiedinto:
MedicalProtozoology.
MedicalHelminthology.
MedicalEntomology.

3. MedicalProtozoology-Dealswithstudyofmedically
importantprotozoa(unicellular)
MedicalHelminthology-Dealswithstudyofhelminthes
MedicalEntomology-Dealswithstudyofarthropods
witchcauseortransmitdiseasetoman

4. Parasites
•Parasitesarelivingorganisms,whichdependonalivinghost
fortheirnourishmentandsurvival.
•Theymultiplyorundergodevelopmentinthehost.

5. Types of parasite
Parasitescanbeclassifiedas:
Endoparasite(endozoa):
Parasitelivesinsidethehost
Ectoparasite(ectozoa):
•Ectoparasitesinhabitonlythebodysurfaceofthehostwithout
penetratingthetissue.Lice,ticks,andmites.
•Theterminfestationisoftenemployedforparasitizationwith
ectoparasites.

6. Free-livingparasite:
Itreferstononparasiticstagesofactiveexistence,whichlive
independentofthehost,e.g.cysticstageofNaegleriafloweri
Obligatoryparasite:
Whichcannotexistwithoutahost,e.g.Toxoplasmagondiiand
Plasmodium.
Facultativeparasite:
Thatcanchangeitslifestylebetweenfree-livingintheenvironment
andparasiticaccordingtothesurroundingconditions.e.g.
Strongyloidesstercoralis.

7. Accidentalparasite:
Whichinfectanunusualhoste.g.Echinococcusgranulosusinfects
manaccidentally,givingrisetohydatidcysts
Opportunisticparasite
Capableofproducingdiseaseinanimmunedeficienthoste.g.
ToxoplasmagondiiandCryptosporidiumparvum.

8. Zoonoticparasite
Primarilyinfectsanimalsandistransmittabletohumanse.g.
Cryptosporidiumparvum,andleishmania.
Wanderingoraberrantparasite:
Whichinfectahostwheretheycannotdevelopfurthere.g.Toxocara
canis(dogroundworm)infectinghumans.

9. Host
Host is defined as:
an organism that harbors a parasitic stage, providing nourishment
and/or shelter to the parasite.

10. Types of host
Definitivehost:
Thehostinwhichtheadultparasitelivesandundergoessexual
reproduction.
Intermediatehost:
Thehostinwhichthelarvalstageoftheparasitelivesorasexual
multiplicationtakesplace.

11. Reservoirhost:
Ahostthatmakestheparasiteavailableforthetransmissionto
anotherhostandisusuallynotaffectedbytheinfection.
Accidentalhost:
Thehostinwhichtheparasiteisnotusuallyfound,e.g.manisan
accidentalhostforEchinococcusgranulosus.

12. Types of life cycle
Directlifecycle:
Whenaparasiterequiresonlysinglehosttocompleteits
development,e.g.Entamoebahistolyticarequiresonlyahumanhost
tocompleteitslifecycle.
Indirectlifecycle:
Whenaparasiterequires2ormorespeciesofhosttocompleteits
development,e.g.malarialparasiterequiresbothhumanhostand
mosquitotocompleteitslifecycle.

13. Host-parasite relationship (symbiosis)
Symbiosis:
An association in which both organisms are so dependent upon each
other, that one can not live without the help of the other.

14. Types of symbiosis
Commensalism:
Anassociationinwhichtheparasiteonlyisderivingbenefitwithout
causinginjurytoitshost.(+/0).
Parasitism:
Asymbioticrelationshipinwhichoneorganism(theParasite)
benefitandother(host)sufferssomeinjury(+/-).
Mutualism:
Mutualismisanyrelationshipinwhichbothorganismsbenefit
(+/+).

17. Classification of parasites
Parasites are classified into:
Protozoa ( unicellular parasites)
Metazoa(helminths)(multicellular parasites)

18. Protozoa
Protozoa are unicellular eukaryotic cells, single cell which
performs all necessary function of metabolism and reproduction.
Belong to Kingdom Protista, Phylum Protozoa.
Morphologically consists of cytoplasm and one or more nucleus.

19. Classification of Parasites

21. Classification of protozoa
Medically important protozoa classified into four subdivisions
according to the methods of locomotion:
1.The amoebae (Sarcodina):move by means of pseudopodia.
2.The flagellates (Mastigophora): typically move by long, whip
like structure called flagella.
3.The ciliates (Ciliata): are move by rows of cilia with a
synchronized wave-like motion.
4.The Apicomplexa(Coccidian) (Sporozoa): lack specialized
organelles of motility.

22. The amoebae

23. The flagellates

24. The ciliates

25. The Apicomplexaor Coccidian

26. Parasites port of entry to
humans
Oral transmission: e.g. Entamoebahistolyticaand Giardia lamblia.
Skin transmission:e.g. schistosomiasis.
Sexual contact: e.g. Trichomonas vaginalis.
Vertical transmission (Congenital ): e.g. Toxoplasma gondii.
Inhalation: e.g. Entrobiusvermicularis.
Kissing: e.g. Entamoebagingivalis.
Blood transfusion: e.g. malaria parasite.
Vectors :e.g. leishmania

27. Amoeba
1.Free-livingamoebas:Theyarewidelydistributedinnature,
foundinfreshwater.FewFree-livingamoebasproducehuman
disease,althoughtwogenera,NaeglariaandAcanthamoebae,
havebeenimplicatedoccasionallyascauseof
meningoencephalitis.
2.Parasiticamoebas:Severalgeneraofamoebasareobligate
parasitesofhumanalimentarytract.

28. Parasitic amoebas :
1.Pathogenic:e.g.Entamoebahistolytica
2.Non-pathogenic:e.g.-Entamoebacoli
-Entamoebahartmanni
-Endolimaxnana
-Iodamoebabutschlii
-Entamoebagingivalis

29. Entamoebahistolytica
Transmission:
•Feco-oralroute(common)
•Vector:fliesandcockroachesmaymechanicallytransmitthecysts
fromfeces,andcontaminatefoodandwater.
•Sexualcontact:especiallyindevelopedcountriesamonghomo-
sexualmales

32. Theamoebaeinvadethecolonicmucosacauselowabdominal
painandacuteattacksofdysenterywithbloodandmucusin
thefaeces(amoebicdysentery).
Systemicinfectionmayarise,leadingtoabscessformationin
internalorgans,especiallytheliver.

33. Intestinal amoebiasis:
•Amoebicdysentery,occurwhenE.histolyticainvadethewallof
thelargeintestine,forminglargeflask-shapedulcers.Theparasite
ingestredbloodcellsfromdamagedcapillaries.

35. The lesion penetrates below the superficial epithelium, it meets the resistance of
the colonic musculature and spreads laterally in the submucosa , producing a
flask-like lesion with narrow mucosal neck and a large submucosal body

37. Complication of intestinal amoebiasis
•Amoebiccolitis
•Intestinalperforation
•Appendicitis
•Amoeboma(amoebicgranuloma)
•Extra-intestinalamoebiasis

39. Extra-intestinal amoebiasis
Amoebasmayalsoentertheportalcirculationandbecarriedto
theliver,lung,brain,andspleen.
Intheseorgans,liquefactionnecrosisleadstotheformationof
abscess.
Amoebicliverabscessispainandtendernessovertheliver,
feverwithchillsandnightsweats.Patientswithlargeormultiple
abscessesmaybecomejaundicedandanaemic

40. Amoebic liver abscess

41. Detection of parasite in aspirates from abscesses

43. Cutaneous amoebiasis
•Whenaliverabscessdrainsthroughtheskinfollowingruptureor
surgicaldrainage,adestructivecutaneousamoebiasismay
developduetotheprolongedcontactoftheskinwithpathogenic
amoeba.

44. Free-living amoeba
•The majority of protozoan species are free -living and have little
impact on human health.
•Free-living protozoa can be found in the environment and are
particularly abundant in soil and water.
•Free-living amoebae which can cause pathology if introduced into
the human host.

45. Pathogenic free-living amoeba
Free-living amoebae known to cause human disease are:
Naegleriafowleri
•Acute Primary Amebic Meningoencephalitis (PAM)
Acanthamoebaspp
•Chronic Granulomatous Amebic Encephalitis (GAE); amebic
keratitis; granulomatous skin and lung lesions.

46. Naegleriafowleri
•Is free-living amoeba typically found in warm fresh water, It causes
a very rare but severe brain infection
•So-called brain-eating amoeba .
•This a species discovered in 1965 by Fowleriin Australia.
•There are several species of Naegleriabut only the fowlerispecies
causes human disease.

47. Morphology of parasite
Exists in 3 form;
•Trophozoite .
•Flagellate form.
•Resistant cyst form.

48. Morphology of trophozoite
Amoeboid form
•Vegetative or feeding
stage.
•This form is found in
CSF or in tissue.

49. Morphology of trophozoite
•The trophozoite is actively motile
with the help of a broadly
rounded, granule-free projection
(lobopodium)

50. Morphology of trophozoite
Flagellateform
•Also known as the
ameboflagellate stage.
•Is a temporary form of the amoeba
in which it neither feeds nor
divides .

51. Morphologyofcyst
•The resistant form of the
parasite.

52. Lifecycle
•The trophozoitestage infect
humans or animals by
penetrating the nasal mucosa
and migrating to the brain via
the olfactory nerves .

53. Lifecycle
•The trophozoites replicate .
•They often turn into
temporary non-feeding
flagellated forms which
usually revert back to the
trophozoite stage.

54. Life cycle
•The amoeboid forms can also
encysted resulting in a stage
resistant to desiccation

58. Sign and symptoms
•Symptomsbegin2-14daysfromexposure.
•Changeintaste/smell.
•Causingprimaryamoebicmeningoencephalitis(PAMorPAME).

59. Sign and symptoms
•PAMisasyndromeaffectingthecentralnervoussystem,
characterizedbychangesinolfactoryperceptionfollowedby
vomiting,nausea,fever,headacheandtherapidonsetofcomaand
deathintwoweeks.

60. Laboratory diagnosis
•Diagnosisisalmostalwayspost-mortemandtheprognosisisnot
good.
•About75%ofdiagnosesaremadeafterthedeathofthepatient.
•DetectNaegleriafowleriorganismsincerebrospinalfluid(CSF)
•Biopsy
•Tissuespecimens.
•PCR.
•Amoebaculture.

61. Prevention
•Holdyournoseshut,usenoseclips,orkeepyourhead
abovewaterduringswimming.
•Avoidwater-relatedactivitiesinwarmfreshwater
duringperiodsofhighwatertemperatureandlow
waterlevels.

62. Acanthamoebaspecies
•ThefamilyAcanthamoebidaeconsistsofthetwogeneracalled
AcanthamoebaandBalamuthia.
•Theseorganismsliveasparasiteswhentheyinvadehumansand
animals.
•TheamoebabelongingtoAcanthamoebaandB.mandrillariscan
leadtovariousillnessesinhumansespeciallyin
immunocompromisedhosts.

63. Distribution
•Are found worldwide.
•They are found in soil, dust, air and water (e.g.
swimming pools).
•Also been isolated in hospitals and contact lenses.

64. Morphology
Active feeding trophozoite
stage:
Actively dividing by feeding on bacteria
and yeast.
Characteristic spine-like pseudopodia.
Dormantcyststage:
•Cysts form when there is a
change in the environment
of the trophozoites, e.g.
nutrient or changes in
temperature.

66. Life cycle
•The amoebas may enter the
respiratory tract by the
inhalation of aerosols or
dust containing cysts
•Spread to the CNS
•In most cases, the portal of
entry is a minor corneal
lesion

68. Sign and symptoms
•Granulomatous amoebic encephalitis
•Cutaneous acanthamoebiasis(Skin lesions)
•Amoebic keratitis

69. Laboratory diagnosis
In cases of granulomatous amebic encephalitis
•Is not diagnosed until after or, at best, shortly before death.
•Computed tomography (CT).
•Magnetic resonance imaging of the brain (MRI).
•Examination of cerebrospinal fluid and brain biopsy specimens
•Immunofluorescence or PCR

70. Laboratory diagnosis
In the case of amebic keratitis
•Scrapings of the corneal ulceration and biopsy specimens may
contain amebic trophozoites and cysts.
•Amoeba may be cultured at 37C.

71. Control
•Hold your nose shut, use nose clips, or keep your head above water
during swimming.
•Correct sterilization of contact lenses.
•Tap water should not be used to rinse contact lenses.
•Health education.

72. Ciliates
Balantidiumcoli

73. Introduction
Balantidiumcoliisthelargestprotozoanandonlyciliateknown
toparasitizehumans.
IsaprotozoanparasiteresponsibleforthediseaseBalantidiasis.
BelongstothephylumCiliophora.
ThiswasfirstdiscoveredbyMalmstenin1857inthefaecesof
twopatientwithacutedysentery.

74. Geographical distribution
•Balantidiumcoli is found world-wide distribution.

75. Morphology of trophozoite
Trophozoite is characterized by:
The presence of cilia on the cell
surface .
A bean shaped macronucleus
which is often visible .
Micronucleus
Contractile vacule and food
vacule.

76. Morphology of cyst
Thick-walled.
Cillia may be seen in
younger cysts.
Macronucleus visible in
stained prepration.

77. Life cycle
•Followingingestion,excystationoccursinthesmallintestine,and
thetrophozoitescolonizethelargeintestine.
•Thetrophozoitesresideinthelumenofthelargeintestineof
humansandanimals,wheretheyreplicatebybinaryfission.

78. Life cycle
•Trophozoitesundergoencystationtoproduceinfectivecysts.
•Sometrophozoitesinvadethewallofthecolonandmultiply.
•Somereturntolumenanddisintegrate.
•Maturecystsarepassedwithfeces.

80. Symptoms and clinical features
•Mostcasesasymptomatic
•Clinicalmanifestationwhenpresentinclude:(diarrheaoccasionally
dysenterywithmucusandblood,abdominalpainandweightloss).
•Inamajorityofpatients,recoveryoccursin3-4daysevenwithout
treatment.
•Symptomscanbesevereindebilitatedpersons.

81. Complication
•Perforationofcolon.
•Peritonitis.
•Gastrointestinalbleeding.

82. Laboratory diagnosis
•Stoolexamination
•FindingB.coliciliatesindysentericfaecalspecimen.
•FindingB.colicystsinformedorsemiformedfaeces.
•Biopsywiththehelpofsigmoidoscopy.
•Culture.

83. Prevention and control
Infection with B.colican be avoided by
•Avoid ingestion of material contaminated with animal feces.
•Improving personal hygiene especially among those who keep
pigs.
•The cysts are rapidly killed by drying but in moist condition they
can remain infective for several weeks.

84. Thank you