Parasitic Diseases

Human Pathogenic Protozoans

“First Animal”Amoebas

Move by pseudopodsCyst trophozoite

FlagellatesMove by flagellaCyst trophozoite

CiliatesMove by cilia

SporozoansDo not have motility structures

Generalized Protozoa Life Cycle

CystProtective form of the organismPassed into the environment

ReproductionAsexually = binary fission; schizogenySexually = gametes

TrophozoiteMotilereplicate

Kingdom ProtistaPhylum : Protozoa

FlagellatesTrichomonasGiardiaTrypanosomaLeishmania

AmoebaeEntamoebaNaegleriaAcanthoamoeba

Phylum ApicomplexaCoccidia

Eimera, IsosporaToxoplasmaCryptosporidiumPlasmodium

PiroplasmasinaBabesia

Phylum CiliophoraBalantidium

New TaxonomyAlveolatesAmoebaeEuglenozoaArchaezoa

AlvelolatesCiliates

2 nucleiApicomplexans

PathogenicIntracellular organelles as apical complex

DinoflagellatesPlanktonSome produce neurotoxins

ArchaezoaLack several organelles

MitochondriaGolgi apparatusperoxisomes

ExamplesDiplomonadida

GiardiaMicrosporidia

Parabasala

EuglenozoaEuglenoids

Characteristics of plants and animalsPhototrophicChloroplastsFlagella + cytoplasm for movementLack cell walls

KinetoplastidsMitochondrial DNA is kinetoplast

AmoebaeLack mitochondriaPseudopodsBinary fission

AMOEBAEntamoeba histolyticaAcanthoamoeba castillanii

Free living, opportunisticCorneal ulceration

Naegleria fowleriFree living, opportunisticCNS fatal meningitis

Entamoeba histolyticaAmoebic dysenteryHumans are DHContaminated waterCystsTrophozoites in lining of SI, colonClinical syndrome

Mucosal necrosisLiver abscesses

DX: Id cystsTX: Metronidizole

Entamoeba histolytica

cyst

CiliatesBalantidium coli

Zoonotic (pigs_Similar to E. histolyticaTrophozoites

Invade intestinal mucosaSevere diarrhea

DX: Id organismTX: TetracyclinePrevention: Hygiene

Balantidium coli

trophozoiteTrophozoites in intestinal lining

FLAGELLATESGiardiaTrichomonasTrypanosoma species

AfricanAmerican

Leishmania speciesCutaneousVisceral

Giardia lamblia5 flagella for motilityCyst ingestionTrophozoite excyst

Motile due to acidAttach to mucosaAbsorbs nutrients

Clinical SignsDiarrhea, NauseaMalabsorption

DX: Id organismTX: MetronidizolePrevention: Sanitation

Giardia

Trophozoite in GI

trophozoite

cyst

Trichomonas vaginalisSTDFemale

Vaginitis: dischargeMale

Urethritis: burningTrophozoite onlyDX: Id organismTX: MetronidizolePrevention: Safe sex

Trichomonas

Trypanosoma bruceiAfrican Sleeping SicknessArthropod vector (Tsetse fly)Animal reservoir = ZoonoticTrypanosomes

Picked up in bloodDevelopment in fly

GutSalivary gland

Chancre at site of bite

Clinical SignsFever, malaiseCNS coma

Trypanosoma trophozoites

Trypanosoma cruziChagas DiseaseAnimal reservoir = ZoonoticVector = Triatomid bugTrypansome

Multiply in bug gutMetacyclic form in fecesOrgansim circulates in bloodAmastigotes in new cellsTrypomastigotes in blood

Clinical CourseNervous: Megaesophagus, mega colonCardiac: arrythmia, dilationGI: pseudocyst in lining

T. cruzi

Chagas Disease

T. cruzi in heart muscle

Leishmania speciesCutaneous

Localized open soreCan spread locally

VisceralSystemicMacrophage location

Animal reservoir = ZoonoticVector: Sand fliesPromastigotes inoculated

Ingested by macrophagesMultiply

AmastigotesReleased and redigestedPicked up by flyMultiply in gut

Leishmania

Amastigotes infectingmacrophages

Leishmaniasis

APICLOMPLEXACryptosporidiumPlasmodiumToxoplasmaCoccidiaBabesia

Cryptosporidium parvumAnimal reservoir = zoonoticFecal contaminated waterOocysts ingestedSporozoites

Invade intestinal cellsAsexual reproduction

Gametes (oocyst)Oocysts in feces

Clinical SyndromeDiarrhea

Self limiting in childrenSevere if immunocompromised

Dx: OocystsTX: Antiprotozoal

Oocysts

Intestinal infections

Plasmodium speciesMalariaVector: Anopheline Mosquitoes

Gametocytes zygoteOocyst in gutSporozoites in salivary glands

Humans = DHSporozoites in liverSchizonts developMerozoites in RBC gametocytes

Clinical CourseInvasion, Rupture, ReinvasionFever, ChillsAnemiaFree Hgb Renal Failure, death

DX: Symptoms, Id bloodTX: antimalarial drugs

Toxoplasma gondiiToxoplasmosisZoonoticFeline = DH; intestinal phaseOocysts

FecesRelease sporozoites replicateTachyzoites form

Encyst in brain, muscleDevelop bradyzoites

Clinical CourseAsymptomaticFetus: miscarriage, handicapAIDS: brain cysts, inflammation

Dx: Ab titer, biopsyTX: TMPS

Toxoplasmosis

tachyzoite

oocystBradyzoite cyst in brain

Don’t look at me…

I’m parasite free!

CoccidiosisNumber of speciesOocysts

IngestedSporozoites

LiberatedAsexual reproduction

Merozoites-> reinfectGametocytes produced

Gametes zygoteoocyst

Clinical DiseaseGI mucosal damageDiarrhea

DX: Oocysts in fecesTX: TMPS

Coccidia

Eimeria in tissue

Babesia bigeminaPiroplasm organismVector: hard TickHost: Mammal RBCsSplenectimized humansClinical Syndrome

Anemia due to destructionFever, achesJaundiceKidney Failure

DX: Id organism in RBCTX: Ab

Pneumocystis jiroveciFormally P. cariniiProtozoan vs FungalSource: Human RespiratoryTransmission @ early ageClinical Course

Cysts in alveolar wallRuptures bodies releasedTrophozoites develop

Sexual repro = cystsAsexual repro = fission

Pneumonia

DX: Id cystsTX: TMPS

PCP

Protozoal Drug TreatmentsMetronidizole

Nicks in DNA

AntimalarialsChloroquine, Amodiaquine, Mefloquine

Eradicate erythrocytic asexual stages

PrimaquineEradicates exoerythrocytic stages

TMPSInhibits metabolites related to Folic acid synthesis

Parasite Prevention Summary And don’t let the

Bed bugs bite!

Wash handsDrink clean waterCook meat and fishWash vegetables & fruitWear shoesControl VectorsPrevention firstDX before TXFollow up / change TX

Questions?