Parasitology ReviewParasitology Review

Margie MorganMargie Morgan

Clinical presentationClinical presentation

Travel history or poor sanitation put you at Travel history or poor sanitation put you at the highest risk for parasitic infectionthe highest risk for parasitic infection

Sporadic symptoms, Sporadic symptoms, Poor immune status higher riskPoor immune status higher risk Dysentery not common (amebiasis)Dysentery not common (amebiasis) Most usual symptoms:Most usual symptoms:

• Abdominal pain, cramping, long term nausea, Abdominal pain, cramping, long term nausea, and malaise, mucous in stool, and +/- feverand malaise, mucous in stool, and +/- fever

Laboratory DiagnosisLaboratory Diagnosis

Currently based on Currently based on microscopic exam, however microscopic exam, however molecular panels are in the molecular panels are in the near futurenear future• StoolStool• Non-stoolNon-stool

Perianal specimenPerianal specimen Sigmoidoscopic specimenSigmoidoscopic specimen Duodenal aspiratesDuodenal aspirates Liver abscessLiver abscess SputumSputum UrineUrine UrogenitalUrogenital

• BloodBlood• TissueTissue

Limited Limited utility/availability of:utility/availability of:• SerologySerology• Fluorescent stainsFluorescent stains• PCRPCR

Two-vial collection kit for StoolTwo-vial collection kit for Stool10% formalin10% formalin Concentration with Concentration with

ethyl acetate to ethyl acetate to eliminate fecal debriseliminate fecal debris

Wet mount and DFA Wet mount and DFA stainingstaining

Helminth eggs, larvae, Helminth eggs, larvae, microsporidia, and microsporidia, and protozoan cystsprotozoan cysts

PVA with fixativePVA with fixative Polyvinyl alcoholPolyvinyl alcohol Permanent stained Permanent stained

smearsmear• Trichrome stainTrichrome stain

Protozoan Protozoan trophozoites and cyststrophozoites and cysts

Mercury based Mercury based fixatives being phased fixatives being phased out for safetyout for safety – – Zinc Zinc fixatives are now usedfixatives are now used

Most Common Pathogens Most Common Pathogens ProtozoaProtozoa

• Intestinal & urogenitalIntestinal & urogenital E histolytica, Blastocystis hominis, Giardia lamblia, E histolytica, Blastocystis hominis, Giardia lamblia,

Dientamoeba fragilis, Balantidium coli, Cryptosporidium Dientamoeba fragilis, Balantidium coli, Cryptosporidium sp., Cyclospora sp, Cyclospora, (Isospora) belli, sp., Cyclospora sp, Cyclospora, (Isospora) belli, andand MicrosporidiaMicrosporidia

• Blood & tissueBlood & tissue Plasmodium, Babesia, TrypanosomesPlasmodium, Babesia, Trypanosomes Toxoplasma gondii, LeishmaniaToxoplasma gondii, Leishmania Naegleria, Acanthamoeba, BalamuthiaNaegleria, Acanthamoeba, Balamuthia

HelminthsHelminths• NematodesNematodes

Ascaris, Trichuris, hookworm, pinworm, and StrongyloidesAscaris, Trichuris, hookworm, pinworm, and Strongyloides• CestodesCestodes

Taenia, Hymenolepis, DiphyllobothriumTaenia, Hymenolepis, Diphyllobothrium• TrematodesTrematodes

Fasciola, Fasciolopsis, Schistosoma, Paragonimus, Fasciola, Fasciolopsis, Schistosoma, Paragonimus, ClonorchisClonorchis

PROTOZOAPROTOZOA Amebae (found in stool)Amebae (found in stool)

• Entamoeba coli Entamoeba coli • Entamoeba histolytica Entamoeba histolytica • Endolimax nanaEndolimax nana• Iodamoeba butschliiIodamoeba butschlii• Dientamoeba fragilisDientamoeba fragilis

Flagellates (found in stool)Flagellates (found in stool)• Giardia lambliaGiardia lamblia• Chilomastix mesniliChilomastix mesnili

Ciliates, Coccidia, BlastocystisCiliates, Coccidia, Blastocystis• BalantidiumBalantidium• CryptosporidiumCryptosporidium• Isospora belliIsospora belli• SarcocystisSarcocystis• CyclosporaCyclospora• MicrosporidiumMicrosporidium• Blastocystis hominisBlastocystis hominis

Blood-Borne ProtozoaBlood-Borne Protozoa• BabesiaBabesia• LeishmaniaLeishmania• Trypanosoma bruceiTrypanosoma brucei• T. cruziT. cruzi• PlasmodiumPlasmodium

Other Other • ToxoplasmaToxoplasma• Naegleria fowleriNaegleria fowleri• AcanthamoebaAcanthamoeba

Protozoa Found in Stool: Amebae Protozoa Found in Stool: Amebae pathogen

Intestinal amoebaIntestinal amoeba Entamoeba coliEntamoeba coli

Entamoeba histolytica/disparEntamoeba histolytica/dispar Entamoeba hartmanniEntamoeba hartmanni

Endolimax nanaEndolimax nana Iodamoeba butschliiIodamoeba butschlii

Entamoeba histolytica/disparEntamoeba histolytica/dispar

E. histolytica is a pathogen and E. dispar is a nonpathogenic E. histolytica is a pathogen and E. dispar is a nonpathogenic species that can also occur in the large intestine. species that can also occur in the large intestine. Morphologically indistinguishableMorphologically indistinguishable

E histolyticaE histolytica• Cysts = infectious form Cysts = infectious form • trophozoites = invasive formtrophozoites = invasive form• Contaminated water and poor sanitationContaminated water and poor sanitation• Colon biopsy shows “flask-shaped” ulcerColon biopsy shows “flask-shaped” ulcer• Non-intestinal disease = extraintestinal amebiasis (liver Non-intestinal disease = extraintestinal amebiasis (liver

abscess)abscess) SerologySerology

Entamoeba histolytica/dispar

Cysts <= 10 umIn diameter Up to 4 nuclei in the cyst

Clean chromatinBulls-eye nucleoli

Entamoeba histolytica/disparEntamoeba histolytica/dispar

Trophozoites & Cysts

Trophozoite with ingested rbcs

Amebic abscessAmebic abscess

Flask-shaped ulcer of intestinal amebiasis

Amebic liver abscessEntamoeba histolyticaSerology – high % positive in extra-intestinal cases

Entamoeba coli cyst and trophozoite

Cyst >=15 mmUp to 8 nucleiShed from hostLives in environment

Trophozoite is the form that invades intestines

Nucleus has a chromatin ringThe cytoplasm appears dirty

Entamoeba coliEntamoeba coli

Trophozoites & Cysts

Endolimax nana trophozoite

Mostly thought to be a non-pathogen, Seen in HIV/AIDS patients, Some literature suggesting it can cause intermittent or chronic diarrhea

Iodamoeba butschlii cysts with starchStaining inclusion

Iodine preparation – name from appearance with iodine staining

FlagellatesFlagellates Giardia lambliaGiardia lamblia Dientamoeba fragilisDientamoeba fragilis Trichomonas vaginalisTrichomonas vaginalis

Protozoa Found in Stool: FlagellatesProtozoa Found in Stool: Flagellates

Giardia lambliaGiardia lamblia Contaminated water, Contaminated water,

undercooked foodsundercooked foods Mild diarrhea to severe Mild diarrhea to severe

malabsorptionmalabsorption Foul, watery diarrheaFoul, watery diarrhea Day-care center outbreaksDay-care center outbreaks Cysts/trophozoites may be Cysts/trophozoites may be

seen in stool, but can be seen in stool, but can be hard to find; Fluorescent hard to find; Fluorescent stains availablestains available

Duodenal aspirationsDuodenal aspirations

TROPHOZOITE“falling leaf” motility

CYSTS

Giardia lamblia trophozoiteWaxing and waning symptomsCan be irregularly Shed in stool material& can be difficult to find

Russia & Mexico-Hot beds

Only invades intestine

Flagyl (Metronidazole) is drug of choice

Giardia lamblia cysts

Giardia lamblia Giardia lamblia cystscysts

Giardia lamblia Giardia lamblia trophozoitestrophozoites

Only invades intestinal tissue

Chilomastix mesniliChilomastix mesnili cyst cyst NonpathogenNonpathogen Mimics Giardia lamblia Mimics Giardia lamblia

cyst – except for clear cyst – except for clear space at end of cystspace at end of cyst

Internal structure looks Internal structure looks like “shepherd’s crook” like “shepherd’s crook” or safety pinor safety pin

Chilomastix mesnili cyst

Clearing Nipple Chilomastix mesnili trophozoite

Dientamoeba fragilisDientamoeba fragilis Diarrhea, anal pruritusDiarrhea, anal pruritus Co-infection with Co-infection with EnterobiusEnterobius

(pinworm)(pinworm)

Trichomonas vaginalisTrichomonas vaginalis Urogenital Urogenital

protozoanprotozoan Scant, watery Scant, watery

vaginal dischargevaginal discharge Four flagella, short Four flagella, short

undulating undulating membranemembrane

Protozoa Found in Stool: Protozoa Found in Stool: Ciliates, Coccidia, Ciliates, Coccidia, BlastocystisBlastocystis

CiliatesCiliates

Balantidium coliBalantidium coli• Mainly in swineMainly in swine• Contact with swine & poor hygieneContact with swine & poor hygiene• Only ciliate that’s pathogenic to humansOnly ciliate that’s pathogenic to humans• Similar disease as amebiasis, but Similar disease as amebiasis, but

extraintestinal invasion rareextraintestinal invasion rare• Largest (50-200 um) trophozoite; Largest (50-200 um) trophozoite;

surface covered with cilia; macronucleussurface covered with cilia; macronucleus• Cyst 40-60 umCyst 40-60 um• Readily identified in fresh, wet mountsReadily identified in fresh, wet mounts

In intestine can cause flask-shaped ulcers like those caused by E. histolytica

Only protozoa with cilia

50 microns

Intestinal Sporozoa (coccidia)Intestinal Sporozoa (coccidia) IsosporaIsospora CryptosporidiumCryptosporidium CyclosporaCyclospora SarcocystisSarcocystis

All are Partial acid fast +

Isospora belliIsospora belli Contaminated food/water, oral-analContaminated food/water, oral-anal Found most commonly in HIV/AIDSFound most commonly in HIV/AIDS Infects intestinal epitheliumInfects intestinal epithelium Malabsorption syndrome mimicking Malabsorption syndrome mimicking

giardiasisgiardiasis

Modified acid fast stain

Isospora belliIsospora belli

Cryptosporidium parvumCryptosporidium parvum Contaminated waterContaminated water Resistant to usual water-purification Resistant to usual water-purification

procedures (chlorination, ozone)procedures (chlorination, ozone) Daycare center outbreaks (fecal-oral)Daycare center outbreaks (fecal-oral) Watery diarrhea; more severe in Watery diarrhea; more severe in

AIDSAIDS

CryptosporidiumCryptosporidiumPartial Acid Fast Positive

Direct Fluorescence Antibody stain – Cryptosporidium parvum

Enzyme immunoassay for the antigen of C. parvum is also available.

False negatives may result due to low organisms numbers (Asymptomatic carriers) in both the EIA and DFA assays

Giardia

C. parvum

Combo stain for CryptosporidiumAnd Giardia lamblia

C. Parvum in intestine

C. Parvum in intestinejust below the plasma membrane

Cyclospora cayetanensisCyclospora cayetanensis Contaminated fruits and vegetablesContaminated fruits and vegetables Watery diarrhea; more sever in Watery diarrhea; more sever in

HIV/AIDSHIV/AIDS Infects upper small bowelInfects upper small bowel Found in vacuoles in cytoplasm of Found in vacuoles in cytoplasm of

jejunal epithelium, villous atrophy, jejunal epithelium, villous atrophy, crypt hyperplasiacrypt hyperplasia

Cyclospora cayetanensis

PAF +6-8 microns

Autofluorescence on FA scope

Also positive on Calcofluorwhite stain

MicrosporidiaMicrosporidia Obligate intracellular pathogenObligate intracellular pathogen Enterocytozoon and Encephalitozoon Enterocytozoon and Encephalitozoon

speciesspecies Primitive eukaryotic organism (fungi)Primitive eukaryotic organism (fungi) Many generaMany genera Infection by ingestion of sporesInfection by ingestion of spores Chronic diarrhea in AIDS patientsChronic diarrhea in AIDS patients Myositis, hepatitis, peritonitis, keratitisMyositis, hepatitis, peritonitis, keratitis

Microsporidia-Common in HIV/AIDS-Watery persistent diarrhea

Positive on modified Trichrome and Calcofluor white stains-Longer staining time will eventually allow for it to work its way into the spore

Blastocystis hominisBlastocystis hominis cysts cysts

Can be a pathogenCan be a pathogen Small #s: can be commensalSmall #s: can be commensal Large #s: pathogenicLarge #s: pathogenic Dirty H20 Dirty H20 Traveler’s diarrhea Traveler’s diarrhea Iodine wet mount

Nuclear blobs Around the periphery Trichrome

stain

None; None; self resolving. self resolving.

Maltese cross in rbcMaltese cross in rbcHemolytic anemia, Hemolytic anemia, Jaundice, fever, Jaundice, fever, hepatomegalyhepatomegaly

Ixodes tickIxodes tickBabesia microtiBabesia microti

Pentosam; Pentosam; Pentamidine Pentamidine isethionate. isethionate.

Intracellular Intracellular (macrophages) (macrophages) leishmanial bodies leishmanial bodies with kinetoplastwith kinetoplast

Visceral leishmaniasis Visceral leishmaniasis (Kala-azar), (Kala-azar), granulomatous skin granulomatous skin lesions lesions Iraq/Iran/AfghanistanIraq/Iran/Afghanistan

Phlebotomine Phlebotomine sandfly sandfly

Leishmania Leishmania donovani donovani

CNS: CNS: melarsoperolmelarsoperolNifurtimox and Nifurtimox and Benzonidazole. Benzonidazole.

Hemoflagellate in Hemoflagellate in blood or tissue. blood or tissue. C- or comma-C- or comma-shapedshaped

American American trypanosomiasis;trypanosomiasis;Chagas disease: Chagas disease: megacolon, cardiac megacolon, cardiac failure.failure.

Reduvid (kissing) Reduvid (kissing) bugbug

T. cruzi T. cruzi

Blood stage: Blood stage: Suramin or Suramin or petamidine petamidine isethionateisethionate

Hemoflagellate in Hemoflagellate in blood or lymph blood or lymph nodenode

African African trypanosomiasis; trypanosomiasis; Sleeping sicknessSleeping sicknessEncephalitis; Encephalitis; cardiac failurecardiac failure

Tsetse flyTsetse flyTrypanosoma Trypanosoma bruceibrucei

TreatmentTreatmentDiagnosisDiagnosisDisease/SymptomsDisease/SymptomsTransmissionTransmissionOrganismOrganism

Blood-Borne Protozoa

TrypanosomesTrypanosomes 2 different diseases2 different diseases

• Chagas disease (American Chagas disease (American trypanosomiasis)trypanosomiasis)

Trypanosoma cruziTrypanosoma cruzi Reduviid / Triatome (kissing) bugReduviid / Triatome (kissing) bug

• African sleeping sickness (African African sleeping sickness (African trypanosomiasis)trypanosomiasis)

T. brucei (gambiense T. brucei (gambiense andand rhodesiense) rhodesiense) Tsetse flyTsetse fly

Trypanosoma bruceiTrypanosoma brucei Sleeping Sleeping sickness (African trypanosomiasis)sickness (African trypanosomiasis)

Vector: Tsetse flyVector: Tsetse fly The two The two T. bruceiT. brucei species that cause species that cause

African trypanosomiasis are African trypanosomiasis are indistinguishable morphologically indistinguishable morphologically • T. b. gambienseT. b. gambiense• T. b. rhodesienseT. b. rhodesiense

A typical trypomastigote has:A typical trypomastigote has:• A small kinetoplast located at the posterior A small kinetoplast located at the posterior

endend• A centrally located nucleusA centrally located nucleus• An undulating membrane, andAn undulating membrane, and• A flagellum running along the undulating A flagellum running along the undulating

membrane, leaving the body at the membrane, leaving the body at the anterior endanterior end

• 14 to 33 µm in length14 to 33 µm in length Trypomastigotes are the only stage found Trypomastigotes are the only stage found

in patients. in patients. 

Trypanosoma brucei gambiense in a blood film

Filamentous structures found in blood

TRYPANOSOMA GAMBIENSE

Trypanosoma cruziTrypanosoma cruzi Chagas Chagas (American trypanosomiasis)(American trypanosomiasis)

Vector: Reduvid/Triatoma (kissing) bugVector: Reduvid/Triatoma (kissing) bug TrypomastigotesTrypomastigotes are the only stage found in are the only stage found in

the the bloodblood of an infected person; may be seen in of an infected person; may be seen in CSF in CNS infectionsCSF in CNS infections

Motile circulating trypomastigotes are readily Motile circulating trypomastigotes are readily seen on slides of fresh anticoagulated blood in seen on slides of fresh anticoagulated blood in acute infection but are rarely detectable by acute infection but are rarely detectable by microscopy in chronic microscopy in chronic T. cruziT. cruzi infection.  infection. 

A typical A typical trypomastigotetrypomastigote has: has:• A large, subterminal or terminal kinetoplast, A large, subterminal or terminal kinetoplast, • A centrally located nucleus, A centrally located nucleus, • An undulating membrane, andAn undulating membrane, and• A flagellum running along the undulating A flagellum running along the undulating

membrane, leaving the body at the anterior end.  membrane, leaving the body at the anterior end.  • 12 to 30 µm in length.  12 to 30 µm in length. 

AmastigoteAmastigote stage parasite may be seen in stage parasite may be seen in histopathology specimens from affected organs.histopathology specimens from affected organs.

C-shape

Trypanosoma cruzi- Possible cardiac infiltration->Chagas

Reduvid bug

LeishmaniaLeishmania Obligate intracellular parasiteObligate intracellular parasite Vector: female sand fly biteVector: female sand fly bite Visceral leishmaniasis (kala azar)Visceral leishmaniasis (kala azar)

• L. donovaniL. donovani Cutaneous leishmaniasisCutaneous leishmaniasis

• L. tropica L. tropica • L. braziliensisL. braziliensis

LeishmaniaLeishmania

Leishmania Leishmania amastigotesamastigotes • Macrophages filled with Macrophages filled with

amastigotes (arrows), several amastigotes (arrows), several of which have a clearly visible of which have a clearly visible nucleus and kinetoplastnucleus and kinetoplast

• Amastigotes are being freed Amastigotes are being freed from a rupturing macrophagefrom a rupturing macrophage

LeishmaniaLeishmania – Clinical Disease – Clinical Disease CutaneousCutaneous

• Single or few chronic, ulcerating Single or few chronic, ulcerating lesions; many specieslesions; many species

• Latin America, southern Europe, Latin America, southern Europe, Middle east, southern Asia, Middle east, southern Asia, AfricaAfrica

• Mucocutaneous in Latin AmericaMucocutaneous in Latin America VisceralVisceral

• primarily primarily L. donovani L. donovani complex complex (Asia), L. infantum/chagasi (Asia), L. infantum/chagasi (Africa and Latin America), (Africa and Latin America), othersothers

• Hepatosplenomegaly, anemia, Hepatosplenomegaly, anemia, cytopenias, systemic symptomscytopenias, systemic symptoms

• India, Bangladesh, Nepal, Sudan, India, Bangladesh, Nepal, Sudan, and Brazil and Brazil

• Important OI in HIV infectionImportant OI in HIV infection

LeishmaniaLeishmania DiagnosisDiagnosis

• Biopsy of infected tissue (skin, bone marrow)Biopsy of infected tissue (skin, bone marrow) Multiple, tiny 2-5 um amastigotes within histiocytesMultiple, tiny 2-5 um amastigotes within histiocytes Distinct Distinct kinetoplastkinetoplast (bar-like structure adjacent to (bar-like structure adjacent to

nucleus)nucleus)• PCRPCR• Urinary antigens (visceral)Urinary antigens (visceral)

DDx of multiple tiny intracellular organismsDDx of multiple tiny intracellular organisms• Leishmania – kinetoplastLeishmania – kinetoplast• Histoplasma – buddingHistoplasma – budding• Toxoplasma – somewhat curved, mostly Toxoplasma – somewhat curved, mostly

extracellularextracellular

Leishmania donovani

Kinetoplast next to nucleusSkin lesion

Sand Fly

BabesiaBabesia Protozoan: Protozoan: B. microti, B. divergensB. microti, B. divergens Zoonosis (deer, cattle, rodents; humans accidental host)Zoonosis (deer, cattle, rodents; humans accidental host) Transmission by Transmission by IxodesIxodes tick bite tick bite Infects red blood cellsInfects red blood cells Found world-wideFound world-wide B. microtiB. microti along the Northeast US along the Northeast US

• Nantucket Island, Martha’s vineyard, Shelter IslandNantucket Island, Martha’s vineyard, Shelter Island Malaria-like syndrome Malaria-like syndrome

• Fever but without periodicity, “B-symptoms”, hemolytic Fever but without periodicity, “B-symptoms”, hemolytic anemia, hemoglobinuria, renal failureanemia, hemoglobinuria, renal failure

Dx:Dx:• Blood smear examinationBlood smear examination

Ring form only (mimics P. falciparum)Ring form only (mimics P. falciparum) Tetrads (unlike P. falciparum)Tetrads (unlike P. falciparum)

Maltese cross(tetrads)

Ixodes tick

Babesia

MALARIAMALARIA ProtozoanProtozoan Transmitted by the anopheles Transmitted by the anopheles

mosquitomosquito Endemic to tropical areasEndemic to tropical areas

Malaria SymptomsMalaria Symptoms Fever and chillsFever and chills SplenomegalySplenomegaly HeadacheHeadache Abdominal painAbdominal pain Diarrhea Diarrhea MyalgiaMyalgia Blackwater fever (hemolysis, Blackwater fever (hemolysis,

hemoglobinuria, renal failure) – P hemoglobinuria, renal failure) – P falciparum onlyfalciparum only

Malaria SymptomsMalaria Symptoms Fever patternFever pattern

ParasiteParasite DiseaseDiseasePlasmodium Plasmodium falciparumfalciparum

MalignantMalignant tertiantertian malariamalaria

P. vivaxP. vivax Benign Benign tertiantertian malaria malariaP. ovaleP. ovale Benign Benign tertiantertian malaria malariaP. malariaeP. malariae QuartanQuartan malaria malaria

Tertian = q 48 hours (every other day)Quartan = q 72 hours

MalariaMalaria Physical exam findingsPhysical exam findings

• FeverFever• SplenomegalySplenomegaly• P. falciparumP. falciparum

JaundiceJaundice HepatomegalyHepatomegaly Increase in respiratory rateIncrease in respiratory rate CNS involvementCNS involvement

Diagnosis: peripheral blood smear (gold standard)Diagnosis: peripheral blood smear (gold standard) Molecular tests are available but not yet widely Molecular tests are available but not yet widely

usedused

MalariaMalaria Distinction is between Distinction is between P. falciparumP. falciparum and and

non-falciparumnon-falciparum• P. falciparumP. falciparum = rapidly progressive and = rapidly progressive and

LETHAL LETHAL ((malignantmalignant tertian fever), often tertian fever), often chloroquine-resistant chloroquine-resistant

• Non-falciparum = rarely cause severe Non-falciparum = rarely cause severe manifestations, often chloroquine sensitivemanifestations, often chloroquine sensitive

Relapsing malariaRelapsing malaria• Dormant hepatic phaseDormant hepatic phase

Hypnozoites of Hypnozoites of P. vivaxP. vivax and and P. ovaleP. ovale

Two in the Liver/Two Not!!Two in the Liver/Two Not!!

Two types of malaria that Two types of malaria that don’tdon’t recur from recur from the liver: the liver: • P. falciparumP. falciparum – high incidence and severity – high incidence and severity• P. malariaeP. malariae – lower incidence and severity – lower incidence and severity

Two types of malaria that Two types of malaria that do do recur from the recur from the liver: liver: • P. vivaxP. vivax – high incidence, most of the world – high incidence, most of the world

except Western Africaexcept Western Africa• P. ovaleP. ovale – lower incidence, occupies the niche in – lower incidence, occupies the niche in

Western AfricaWestern Africa

MALARIA

Life Cycle of Plasmodium Species

RBC formsRBC forms

Ring form Ring form Trophozoite Trophozoite Schizont Schizont

Gametocyte

Merozoites(ruptured schizont)

PlasmodiumPlasmodium species species Plasmodium falciparumPlasmodium falciparum Plasmodium vivaxPlasmodium vivax Plasmodium ovalePlasmodium ovale Plasmodium malariaePlasmodium malariae

P. falciparumP. falciparum P. vivax, P. P. vivax, P. ovaleovale

P. malariaeP. malariae BabesiaBabesia

VectorVector MosquitoMosquito MosquitoMosquito MosquitoMosquito Ixodes tickIxodes tickRBC RBC Any RBCAny RBC Young RBC; Young RBC;

enlargedenlargedMature RBC;Mature RBC;Not enlargedNot enlarged

RingRing Multiple can Multiple can be seen; be seen; delicate; delicate;

“appliqu锓appliqué”

Rarely >1;Rarely >1;thickenedthickened

1-121-12Tetrads Tetrads

((Maltese Maltese crosscross))

DelicateDelicateRings onlyRings only

SchizontSchizont Rarely seenRarely seen Commonly seenCommonly seen ““rosette”rosette” nonenoneGametocyteGametocyte Banana-Banana-

shapedshapedRoundRound nonenone

Extra-RBC Extra-RBC formform

NoneNone NoneNone PresentPresent

Schüffner dotsSchüffner dots NoNo YesYes NoNoPigmentationPigmentation BrownBrown NoNoInfection rateInfection rate >2%>2% <2%<2% 5-10%5-10%Protective Protective polymorphismpolymorphismss

Hemoglobin S, Hemoglobin S, C,E, alpha and C,E, alpha and

beta thal, G6PDbeta thal, G6PD

Duffy negative Duffy negative (P. vivax)(P. vivax)

Dormant Dormant hepatic phase hepatic phase (relapse)(relapse)

NoNo YesYes NoNo

Malarial PreparationsMalarial Preparations

Thick smearThick smear Drop of blood on slideDrop of blood on slide Water rinse to Water rinse to

eliminate rbc’seliminate rbc’s Stain with Giemsa Stain with Giemsa

stain (not Wright-stain (not Wright-Giemsa) with Giemsa) with proper proper pHpH

Concentrated to spot Concentrated to spot malaria parasitesmalaria parasites

Thin smearThin smear Feather edge smearFeather edge smear For optimal For optimal

morphology, stain with morphology, stain with GiemsaGiemsa (not Wright- (not Wright-Giemsa) stain with Giemsa) stain with proper pHproper pH

SpeciationSpeciation of malaria of malaria Parasitemia (%)Parasitemia (%)

MalariaMalariaDiagnosisDiagnosis

Microscopy is most often usedMicroscopy is most often used Antigen detection – EIA availableAntigen detection – EIA available Molecular methods Molecular methods

P. ovaleP. ovale

“Rosette” schizont

P. malariaeP. malariae

P. vivaxP. vivax

Amoeboid ring form

P.Vivax – benign tertian malaria (every 48 hours), Duffy negative RBC is protectiveAfricans lack Duffy rbc antigen and this prevents rbc invasion.Untreated infections last several years; dormant in the liver for yearsPatients can survive years without treatment, but chronic infection can lead to brain, kidney and liver damage

P. falciparumP. falciparum

Malignant tertian malariaBlack water fever

P. falciparumP. falciparum

PlasmodiumPlasmodiumspeciesspecies

P. falcipriumP. falciprium Non-Non-FalciparumFalciparum

BabesiaBabesia

VectorVector MosquitoMosquito MosquitoMosquito Ixodes tickIxodes tickRBC RBC All RBCAll RBC Young RBCYoung RBCRingRing 1-31-3

delicatedelicateRarely >1Rarely >1thickenedthickened

1-121-12TetradsTetradsDelicateDelicateRings onlyRings only

GametocyteGametocyte Banana Banana shapedshaped

roundround nonenone

Extra-RBC Extra-RBC formform

NoneNone NoneNone PresentPresent

PigmentationPigmentation BlackBlack brownbrown nonenoneInfection rateInfection rate >2%>2% <2%<2% 5-10%5-10%Protective Protective polymorphispolymorphismsms

Hemoglobin S, Hemoglobin S, C,E, alpha and C,E, alpha and beta thal, G-6-beta thal, G-6-PDPD

Duffy negativeDuffy negative

Other ProtozoaOther Protozoa

• ToxoplasmaToxoplasma

OrganismOrganism TransmissionTransmission Disease/Disease/SymptomsSymptoms

DiagnosisDiagnosis TreatmentTreatment

Toxoplasma Toxoplasma gondiigondii

Oral from cat fecal Oral from cat fecal materialmaterialor meator meat

Adult: flu like;Adult: flu like;congenital: congenital: abortion, neonatal abortion, neonatal blindness and blindness and neuropathiesneuropathies

Intracellular (in Intracellular (in macrophages) macrophages) tachyzoites tachyzoites

SulphonamidesSulphonamides, , pyemethaminepyemethamine, possibly , possibly spiramycin spiramycin (non-FDA)(non-FDA)

Toxoplasma gondiiToxoplasma gondii Coccidian protozoanCoccidian protozoan House cat = definitive hostHouse cat = definitive host Ingestion of infective oocysts from contaminated Ingestion of infective oocysts from contaminated

cat fecescat feces Ingestion of improperly cooked meat from Ingestion of improperly cooked meat from

animals that serve as intermediate hosts animals that serve as intermediate hosts (rodents)(rodents)

SymptomsSymptoms• Predilection for lung, heart, lymphoid organs, CNS/eyePredilection for lung, heart, lymphoid organs, CNS/eye• Infectious mono-like; lymphadenitis, hepatitis, rash, Infectious mono-like; lymphadenitis, hepatitis, rash,

encephalomyelitis, myocarditis, chorioretinitisencephalomyelitis, myocarditis, chorioretinitis• Transplacental infectionTransplacental infection

11stst trimester trimester spontaneous abortion, stillbirth or severe spontaneous abortion, stillbirth or severe diseasedisease

22ndnd/3/3rdrd trimester trimester CNS infections (epilepsy, encephalitis, CNS infections (epilepsy, encephalitis, intracranial calcifications, MR, chorioretinitis, blindness, intracranial calcifications, MR, chorioretinitis, blindness, hearing loss), jaundice, rashhearing loss), jaundice, rash

• AIDS - Encephalitis; mass lesions in brainAIDS - Encephalitis; mass lesions in brain

Toxoplasmagondii

Strongly associated with young Kittens

Toxoplasma gondiiToxoplasma gondii DiagnosisDiagnosis

• Serology EIASerology EIA Anti-toxo IgM – congenital and acute Anti-toxo IgM – congenital and acute

infection; may persist for monthsinfection; may persist for months Anti-toxo IgG – common; if positive, Anti-toxo IgG – common; if positive,

gestations safe from intrauterine gestations safe from intrauterine toxoplasmosis infectiontoxoplasmosis infection

• PCRPCR

Toxoplasma gondii

Can be diagnosed by serology

Toxoplasma gondiiToxoplasma gondii

Toxoplasma gondiiToxoplasma gondii cyst in brain tissue cyst in brain tissue stained with hematoxylin and eosinstained with hematoxylin and eosin

Free-living AmoebaFree-living Amoeba Naegleria fowleriNaegleria fowleri AcanthamoebaAcanthamoeba BalamuthiaBalamuthia

Amoebic meningoencephalitisAmoebic meningoencephalitis Most commonly caused by Most commonly caused by Naegleria Naegleria

fowlerifowleri Granulomatous amoebic encephalitis Granulomatous amoebic encephalitis

or brain abscess(es) caused by or brain abscess(es) caused by AcanthamoebaAcanthamoeba and and BalamuthiaBalamuthia

Clinical scenario: swimming or Clinical scenario: swimming or diving in fresh-water poolsdiving in fresh-water pools

Brain tissue with Naegleria fowleri trophozoite

Naegleria fowleri-Found in warm fresh water-Breath-in through nose-> brain

Brain tissue with Naegleria fowleri trophozoites

Contact-lens keratitisContact-lens keratitis Caused by Caused by AcanthamoebaAcanthamoeba Can be cultured on a “lawn of Can be cultured on a “lawn of E. coliE. coli””

• Take corneal scapingsTake corneal scapings• Visible trail of ameba moving across Visible trail of ameba moving across

plate ingesting plate ingesting E. coliE. coli

AcanthamoebaAcanthamoeba

HELMINTHSHELMINTHS Nematodes (roundworms)Nematodes (roundworms) Trematodes (flukes)Trematodes (flukes) Cestodes (tapeworms)Cestodes (tapeworms)

NematodesNematodes EnterobiusEnterobius AscarisAscaris TrichurisTrichuris Necator and Ancylostoma Necator and Ancylostoma

(Hookworm)(Hookworm) Microfilaria – Wucheria, Brugia, Loa Microfilaria – Wucheria, Brugia, Loa

loa, Mansonella, and Onchocercaloa, Mansonella, and Onchocerca

Enterobius vermicularis (pinworm)Enterobius vermicularis (pinworm) Humans considered only hostHumans considered only host Females 8-13mm, males 2-5 mmFemales 8-13mm, males 2-5 mm Dwell in the cecumDwell in the cecum ¼-1/2 inch in thickness, white, lloks like ¼-1/2 inch in thickness, white, lloks like

string in stoolstring in stool Lay up to 15,000 eggsLay up to 15,000 eggs

• Oval with a flattened side: 50-60um by 20-30umOval with a flattened side: 50-60um by 20-30um Diagnosis- Scotch tape test or anal swabDiagnosis- Scotch tape test or anal swab Most common helminth in USMost common helminth in US

Enterobius vermicularis (pinworm) eggs

Asymmetrical eggs

Pinworm larvae

Ascaris lumbricoides (roundworm)Ascaris lumbricoides (roundworm)

1-1.2 billion people infected1-1.2 billion people infected• More common in childrenMore common in children

20,000 death20,000 death Largest helminth to affect humansLargest helminth to affect humans Females 20-35cm long, males 15-Females 20-35cm long, males 15-

30cm with a curved tale30cm with a curved tale• Can cause intestinal obstruction Can cause intestinal obstruction

Ascaris lumbricoides

Ascaris eggs

Unfertilized eggs-large & oval, mammillated layer is pronounced

Fertilized eggs- smaller, rounder, mammillated layer is less obvious

Trichuris Trichiura (whipworm)Trichuris Trichiura (whipworm) Soil transmittedSoil transmitted Can be similar to amebiasisCan be similar to amebiasis PVA preserved samples inferior to formalinPVA preserved samples inferior to formalin Adults attach to large intestine and are Adults attach to large intestine and are

rarely recoveredrarely recovered Thinnest part- headThinnest part- head Males are smaller than femalesMales are smaller than females

Trichuris trichiura

Necator americanus, Anclyostoma Necator americanus, Anclyostoma duodenale (Hookworms)duodenale (Hookworms)

Soil transmittedSoil transmitted 22ndnd most common helminth infection most common helminth infection Enter via exposed skinEnter via exposed skin

Necator or Ancylostoma – Hookworm egg

Hookworm life cycle

Strongyloides stercoralisStrongyloides stercoralis Soil transmittedSoil transmitted Larval form-does not have eggs or other formsLarval form-does not have eggs or other forms It has internal structuresIt has internal structures

Strongyloides larvae

Strongyloides stercoralis

Can be found in intestines or stoolsIn real sick can go to lung and cause pneumonia

Trichinella spiralis

-Tissue nematode-All stages occur in single host-usually an incidental findingin muscle

MicrofilariaeMicrofilariae SheathedSheathed

• Wucheria bancrofti Wucheria bancrofti and and Brugia malayiBrugia malayi Elephantiasis (lymphangitis/lymphedema)Elephantiasis (lymphangitis/lymphedema)

• Loa loaLoa loa Calabar swellings & migrating worms in the Calabar swellings & migrating worms in the

conjunctivaconjunctiva Not sheathedNot sheathed

• Onchocerca volvulusOnchocerca volvulus• MansonellaMansonella species species

Allergic skin reactions, edema, Calabar swellingsAllergic skin reactions, edema, Calabar swellings

How to tell them apartHow to tell them apart Are they sheathed?Are they sheathed?

• Yes: Wucheria, Brugia, Loa loaYes: Wucheria, Brugia, Loa loa• No: Onchocerca, MansonellaNo: Onchocerca, Mansonella

How far do nuclei extend?How far do nuclei extend?• Terminal and subterminal nucleus: Terminal and subterminal nucleus:

BrugiaBrugia• To the end: Loa loaTo the end: Loa loa

 Identification of microfilariae is based on the presence of a sheath covering the larvae, as well as the distribution of nuclei in the tail region

A, W. bancrofti. B, B. malayi. C, L. loa. D, O. volvulus. E, Mansonella perstans. F, Mansonella streptocerca. G, Mansonella ozzardi.

FilariaFilariaIdentificationIdentification

a.a. W. bancroftiW. bancrofti• Sheathed, nuclei Sheathed, nuclei

stop short of end of stop short of end of tailtail

b.b. B. malayiB. malayi• Sheathed, two small Sheathed, two small

nuclei in tailnuclei in tailc.c. O. volvulusO. volvulus

• Unsheathed, from Unsheathed, from skin, not bloodskin, not blood

d.d. Loa loaLoa loa• Sheathed, nuclei to Sheathed, nuclei to

continue to end of continue to end of tailtail

Wucheria bancrofti

Wuchereria bancroftiWuchereria bancrofti

Sheath

Brugia malayi

Brugia malayiBrugia malayi

Loa loa

Loa loaLoa loa (eye worm) (eye worm)

Mansonella perstans

OnchocerciasisOnchocerciasis

Black fly

Onchocerciasis

Trematodes (Flatworms)Trematodes (Flatworms)

Intestinal and Liver flukesIntestinal and Liver flukes• Fasciolopsis buskiFasciolopsis buski• Fasciola hepaticaFasciola hepatica

Liver flukesLiver flukes• Clonorchis sinensis (Chinese liver fluke)Clonorchis sinensis (Chinese liver fluke)

Paragonimus westermani – oriental lung flukeParagonimus westermani – oriental lung fluke SchistosomesSchistosomes

• S mansoni – intestinal bilharziasisS mansoni – intestinal bilharziasis• S haematobium - urinaryS haematobium - urinary• S japonicum – blood fluke, found in intestinesS japonicum – blood fluke, found in intestines

Intestinal and liver flukes

Fasciola hepatica

Distinct nose

Fasciolopsis buski Fasciola hepatica

Fasciolopsis buski

Fasciolopsis buski

Clonorchis sinensis

knobbin

Shouldersoperculates

Transmission: Crab or crayfishSymptoms: chest pain, hemoptysiscough, pulmonary infiltrates, cerebral lesionsDiagnosis: Eggs is sputum or feces

Egg is operculate, unembryonated, thick shell, asymmetrical and large

Paragonimus westermani

Schistosoma mansoniiParagonimus westermani

Schistosoma mansoni Schistosoma haematobium Schistosoma jajonicum

Cestodes (Tapeworms)Cestodes (Tapeworms)

ExamplesExamples Diphyllobothrium Diphyllobothrium

latumlatum Taenia saginataTaenia saginata Taenia soliumTaenia solium Hymenolepis nanaHymenolepis nana Hymenolepis diminutaHymenolepis diminuta Echinococcus Echinococcus

granulosisgranulosis

Flattened dorsoventrally, segmentedHead with armed or unarmed scolexProglottids immature, mature (sex organs)Gravid (with eggs)

Internal structure of proglottidsHermaphroditic-ovary, testes, vitellaria, uterus, genital pore and ducts

Lateral excretory and nervous system

No gut-tegument absorbs nutrients

Muscles-longitidinal and horizontal

Diphyllobothrium latum

Diphyllobothrium latumDiphyllobothrium latum Poorly-cooked fresh-water fish(salmon)Poorly-cooked fresh-water fish(salmon) Scandinavian, Russia, Canada, N. USA, Scandinavian, Russia, Canada, N. USA,

AlaskaAlaska Broad fish tapewormBroad fish tapeworm Longitudinal suckerLongitudinal sucker Eggs have non-shouldered operculum and Eggs have non-shouldered operculum and

knobknob• They are not embryonatedThey are not embryonated

Causes Vit B12 deficiencyCauses Vit B12 deficiency

Diphyllobothrium latum

Sucking plate

Diphyllobothrium latum

Taenia saginata

Beef tapeworm 4 suckers on scolex >13 uterine branches in proglottidsIngestion of cysticerci in beef

Intestinal infestationIngestion of eggs ->

Non-human pathogen

Taenia Solium

Pig tapewormRing of thorns/crown on scolex<13 uterine branches in proglottidsIngestion of cysticerci in pork

Intestinal infestationIngestion of eggs ->

Cysticercosis

Taenia Species – two speciesOutstanding characteristics

Taenia species

Taenia eggsIdentical eggs for the two species

Taenia saginata

Proglottid > 12 uterine branches

Taenia solium

Proglottis – fewer uterine branches(<=12 uterine branches)

Scolex - Ring of thorns

Cysticercosis

Caused by the ingestion of T. solium eggsNot eating infected pork

Cysts of Cysticercosis

Hymenolepis nana

Hymenolepis nanaMost common cestode recovered in USAWorm is 2-4 cmEgg has inner & outer shell separated

spaceWater /food contaminated by rodent droppings

Hooklets inside

Larger outer shellNo radial striations

Hymenolepis diminutaUncommon tapewormBig egg @ 80 microns in diameter

Echinococcus – hydatid cyst

Echinococcus – hydatid cyst

Short tapewormSand like materialContained in the cyst

Tapeworms

Relative size of Helminth eggsRelative size of Helminth eggs

http://www2.bc.cc.ca.us/bio16/pal/Parasitology.htm

Insects of interest – not already Insects of interest – not already mentionedmentioned

Maggots

Bot fly larvae

Extrudes from the skin

Ticks of importance

Soft tick -Expands with bloodengorgement

Hard Ticks

Black Widow spider

Hour glassOn tummy

FleaBody louse

Crab louse

Hair nitBody Louse

Scabies

Tiny

egg

s un

der s

kin

Mite