Parasitology Review 2017

Parasitology Review2017MARGIE MORGAN

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

Infections associated with sporadic symptoms Poor immune status higher risk Dysentery not common (amebiasis) Most usual symptoms:

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

Laboratory DiagnosisCurrently based on microscopic exam, and molecular panels for the most common (select) parasites

◦ Stool (PCR applicable)◦ Non-stool

◦ Perianal specimen◦ Sigmoidoscopic specimen◦ Duodenal aspirates◦ Liver abscess◦ Sputum◦ Urine◦ Urogenital

◦ Blood◦ Tissue

Alternative methods:◦ Serology◦ Fluorescent stains

Two-vial collection kit for Stool

10% formalin Concentration with ethyl acetate to eliminate fecal debris

Wet mount, DFA staining and NAAT

Helminth eggs, larvae, microsporidia, and protozoan cysts

PVA with fixative Polyvinyl alcohol Permanent stained smear

◦ Trichrome stain

Protozoan trophozoites and cysts

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

Most Common Pathogens Protozoa

◦ Intestinal & urogenital◦ E histolytica, Blastocystis hominis, Giardia lamblia, Dientamoeba fragilis,

Balantidium coli, Cryptosporidium sp., Cyclospora sp, Cyclospora, Cytoisospora(Isospora) belli, and Microsporidia

◦ Blood & tissue◦ Plasmodium, Babesia, Trypanosomes◦ Toxoplasma gondii, Leishmania◦ Naegleria, Acanthamoeba, Balamuthia

Helminths◦ Nematodes

◦ Ascaris, Trichuris, hookworm, pinworm, and Strongyloides◦ Cestodes

◦ Taenia, Hymenolepis, Diphyllobothrium◦ Trematodes

◦ Fasciola, Fasciolopsis, Schistosoma, Paragonimus, Clonorchis

PROTOZOA Amebae (found in stool)

◦ Entamoeba coli ◦ Entamoeba histolytica ◦ Endolimax nana◦ Iodamoeba butschlii◦ Dientamoeba fragilis

Flagellates (found in stool)◦ Giardia lamblia◦ Chilomastix mesnili

Ciliates, Coccidia, Blastocystis◦ Balantidium◦ Cryptosporidium◦ Cystoisospora (Isospora) belli◦ Sarcocystis◦ Cyclospora◦ Microsporidium◦ Blastocystis hominis

Blood-Borne Protozoa◦ Babesia◦ Leishmania◦ Trypanosoma brucei◦ T. cruzi◦ Plasmodium

Other ◦ Toxoplasma◦ Naegleria fowleri◦ Acanthamoeba

Protozoa Found in Stool: Amebae pathogen

Intestinal amoeba Entamoeba coli

Entamoeba histolytica/dispar

Entamoeba hartmanni

Endolimax nana

Iodamoeba butschlii

Entamoeba histolytica/dispar E. histolytica is a pathogen and E. dispar is a nonpathogenic species that can also occur in the large intestine. Morphologically indistinguishable◦ Antigen testing or molecular methods to distinguish the two species

E histolytica◦ Cysts = infectious form ◦ Trophozoites = invasive form◦ Cysts found in contaminated water and poor sanitation◦ Colon biopsy shows “flask-shaped” ulcer with Trophs◦ Non-intestinal disease = extra-intestinal amebiasis (liver

abscess) with Trophs◦ Serology can be useful


Cysts @10-12 umIn diameter Up to 4 nuclei in the cyst

Peripheral chromatin is evenClean chromatin

Bulls-eye nucleoli


Trophozoites & Cysts

Trophozoite with ingested rbcs

Elongated chromatoidbody

Amebic abscess

Flask-shaped ulcer of intestinal amebiasis

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

Entamoeba coli cyst and trophozoiteConsidered a commensal in the intestine

Cyst @ 20 – 25µmUp to 8 nucleiShed from hostLives in environment

Trophozoite is the invasive form that invades the intestine

Single nucleus with a large karyosome located eccentrically irregular chromatin ring.The cytoplasm appears dirty and vacuolated

Entamoeba coli – important to differentiate from the pathogen E. histolytica

Trophozoites & Cysts

Cysts usually15-25µm, with 5or more nucleivisible.

Endolimax nana trophozoite

Cysts – 8-10 µm in size, one nucleusMostly thought to be a non-pathogen, seen in stool specimens from HIV/AIDS patients, some literature suggesting it can cause intermittent or chronic diarrhea

Iodamoeba butschlii cysts, 10 – 12 µm insize with starch inclusion (glycogen mass)

Iodine preparation – glycogen inclusion stains with iodine

Flagellates Giardia lamblia Dientamoeba fragilis Trichomonas vaginalis

Protozoa Found in Stool: Flagellates

Pathogen

Giardia lamblia Contaminated water, undercooked foods

Mild diarrhea to severe malabsorption

Foul, watery diarrhea Day-care center outbreaks reported, traveler’s diarrhea

Cysts/trophozoites may be seen in stool, but can be hard to find; Fluorescent stains and NAAT for more sensitive detection

Duodenal aspirations can be used if stool specimens are negative

TROPHOZOITE“falling leaf” motility

CYSTS

Giardia lamblia trophozoiteWaxing and waning symptomsCan be irregularly shed in stool materialmaking antigen and molecular methods necessary for detection

Russia & Mexico-Hot beds of infection

Confined to intestine

Flagyl (Metronidazole) is drug of choice

Giardia lamblia cysts

Clearing between the cell wall and the cell membrane

Giardia lamblia cysts

Giardia lambliaonly invades intestinal tissue

Chilomastix mesnili cyst Nonpathogen Mimics Giardia lamblia cyst – except for clear space at end of cyst

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

C. mesnili trophozoite

Dientamoeba fragilis Diarrhea, anal pruritus Only a trophozoite stage 5 – 15 µm (No cyst) Usually two nuclei visible in the trophozlite Can occur in Co-infection with Enterobius (pinworm)

Trichomonas vaginalis Urogenital protozoan Scant, watery vaginal discharge

Four flagella, short undulating membrane

Protozoa Found in Stool: Ciliates, Coccidia, Blastocystis

Ciliates Balantidium coli

◦ Mainly in swine◦ Contact with swine & poor hygiene◦ Only ciliate that’s pathogenic to humans◦ Similar disease as amebiasis, but extraintestinal invasion

rare◦ Largest (50-200 um) trophozoite; surface covered with

cilia; macronucleus◦ Cyst 40-60 um◦ Readily identified in fresh, wet mounts◦ Can cause flask shaped ulcer in intestine

Intestinal Sporozoa (coccidia)

Isospora (Cystoisospora) Cryptosporidium Cyclospora Sarcocystis

Isospora(Cystoisospora) belli

Contaminated food/water, oral-anal Found most commonly in HIV/AIDS Infects intestinal epithelium Malabsorption syndrome mimicking giardiasis

PositiveModified acid fast stain

Cryptosporidium sppC. parvum and C. hominis

Contaminated water Resistant to usual water-purification procedures (chlorination, ozone)

Daycare center outbreaks (fecal-oral), swimming pools

Watery diarrhea; more severe in AIDS

Cryptosporidiosis: DiagnosisPartial Acid Fast Stain Positive

Not detected in routine O & P exams (left)Requires modified acid-fast stains for detection, oocysts measure4-6 µm , Antigen, DFA and Molecular assays aid detection.

PAF stain Positive

Direct Fluorescence Antibody stain – Cryptosporidium spp

Molecular assays (PCR) and Enzyme immunoassay for antigen available.

Giardia

Cryptosporidium

Combo stain for Cryptosporidiumand Giardia lamblia

Cryptosporidia in intestine

Cryptosporidia in the intestine - locatedjust below the plasma membrane

Cyclospora cayetanensis Contaminated fruits and vegetables – particularly ones with plant hairs

Watery diarrhea; fatigue, anorexia, weight loss, flu like symptoms. More severe in immune suppressed, can last for months

Infects upper small bowel Treatment Oral Trimethoprim/sulfamethoxazole Found in vacuoles in cytoplasm of jejunal epithelium, villous atrophy, crypt hyperplasia

Cyclospora cayetanensis

Modified acid fast positive8-10 microns

UV autofluorescence

Also positive on Calcofluorwhite stain

Microsporidia Obligate intracellular fungal parasite Enterocytozoon and Encephalitozoon species most common genera

Primitive eukaryotic organism (fungi) Infection by ingestion of spores Chronic diarrhea in AIDS patients Myositis, hepatitis, peritonitis, keratitis, gastrointestinal and biliary tract

Microsporidia-Diagram of detailed internal sporestructures

Positive on modified Trichrome and Calcofluor white stains

-Longer staining times will eventually allow for it to work its way into the spore

Blastocystis hominis (algae)

Small #s: can be commensal Large #s: may be pathogenic Contaminated food and H20 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 sandfly Phlebotomine sandfly Leishmania donovani Leishmania donovani

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

Hemoflagellate in Hemoflagellate in blood or tissue. blood or tissue. C- or comma-shapedC- or comma-shaped

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

Reduvid (kissing) bugReduvid (kissing) bugT. cruzi T. cruzi

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

Hemoflagellate in Hemoflagellate in blood or lymph nodeblood or lymph node

African African trypanosomiasis; trypanosomiasis; Sleeping sicknessSleeping sicknessEncephalitis; cardiac Encephalitis; cardiac failurefailure

Tsetse flyTsetse flyTrypanosoma bruceiTrypanosoma brucei

TreatmentTreatmentDiagnosisDiagnosisDisease/SymptomsDisease/SymptomsTransmissionTransmissionOrganismOrganism

BLOOD BORNE PROTOZOA

Trypanosomes 2 Diseases

◦ Chagas disease (American trypanosomiasis)◦ Trypanosoma cruzi◦ Vector: Reduviid / Triatome (kissing) bug

◦ African sleeping sickness (African trypanosomiasis)◦ T. brucei (gambiense and rhodesiense)◦ Vector: Tsetse fly

Trypanosoma cruzi Chagas (American trypanosomiasis)

Vector: Reduvid/Triatoma (kissing) bug Trypomastigotes are the only stage found in the blood of an infected person; may be seen in CSF in CNS infections

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

A typical trypomastigote has:◦ A large, subterminal or terminal kinetoplast, ◦ A centrally located nucleus, ◦ An undulating membrane, and◦ A flagellum running along the undulating membrane, leaving the body

at the anterior end. ◦ 12 to 30 µm in length.

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

C-shape

Trypanosoma cruzi – TrypomastigotePeripheral blood – Giemsa stain

Reduvid bug

Amastigote of T. cruzi in cardiactissue

Trypanosoma brucei Sleeping sickness (African trypanosomiasis)

The two T. brucei species that cause African trypanosomiasis are indistinguishable morphologically

◦ T. brucei gambiense◦ T. brucei rhodesiense

A typical trypomastigote has:◦ A small kinetoplast located at the posterior end◦ A centrally located nucleus◦ An undulating membrane, and◦ A flagellum running along the undulating membrane, leaving

the body at the anterior end◦ 14 to 33 µm in length

Trypomastigotes are the only stage found in patients. kinetoplast

nucleus

TRYPANOSOMA BRUCEI GAMBIENSE

Leishmania Obligate intracellular parasite Vector: female sand fly bite Two forms of disease

◦ Visceral leishmaniasis (kala azar)◦ L. donovani

◦ Cutaneous leishmaniasis◦ L. tropica ◦ L. braziliensis

Leishmania

Leishmania – Clinical Disease

Cutaneous◦ Single or few chronic, ulcerating lesions;

many species◦ Latin America, southern Europe, Middle east,

southern Asia, Africa◦ Mucocutaneous in Latin America

Visceral◦ primarily L. donovani complex (Asia), L.

infantum/chagasi (Africa and Latin America), others

◦ Hepatosplenomegaly, anemia, cytopenias, systemic symptoms

◦ India, Bangladesh, Nepal, Sudan, and Brazil ◦ Important OI in HIV infection

Leishmania Diagnosis

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

◦ PCR methods◦ Urinary antigens (visceral)

DDx of multiple tiny intracellular organisms◦ Leishmania – kinetoplast◦ Histoplasma – budding◦ Toxoplasma – somewhat curved, mostly extracellular

Leishmania amastigotes ◦ Macrophages filled with amastigotes (arrows),

several of which have a clearly visible nucleus and kinetoplast

Nucleus

Kinetoplast

Babesia Protozoan: B. microti, B. divergens Zoonosis (deer, cattle, rodents; humans accidental host) Transmission vector: Ixodes tick bite Infects red blood cells Found world-wide B. microti along the Northeast US

◦ Nantucket Island, Martha’s vineyard, Shelter Island

Malaria-like syndrome ◦ Fever but without periodicity, “B-symptoms”, hemolytic anemia,

hemoglobinuria, renal failure

Dx:◦ Blood smear examination

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

Maltese cross(tetrads)

Ixodes tick

Babesia

Maltese cross forms

MALARIA Protozoan parasite Transmitted by the anopheles mosquito Endemic in tropical areas

Malaria Symptoms Fever 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

Malaria Physical exam findings

◦ Fever◦ Splenomegaly◦ P. falciparum - most pathogenic species

◦ Jaundice◦ Hepatomegaly◦ Increase in respiratory rate◦ CNS involvement◦ Blackwater fever – hemolysis, renal failure

Diagnosis: peripheral blood smear Antigen screen (EIA) and NAAT

Malaria Primary distinction is P. falciparum and non-falciparum disease◦ P. falciparum = rapidly progressive and LETHAL (malignant

tertian fever), often chloroquine-resistant ◦ Non-falciparum = rarely cause severe manifestations, often

chloroquine sensitive

Relapsing malaria◦ Dormant hepatic phase can recur from liver

◦ Occurs only with P. vivax and P. ovale

MALARIA

Life Cycle of Plasmodium Species

Progression of the RBC formsof Malaria

Ring form Trophozoite Schizont

Gametocyte

Merozoites(ruptured schizont)

Plasmodium species Plasmodium falciparum Plasmodium vivax Plasmodium ovale Plasmodium malariae Plasmodium knowlesi – primates only

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;

“appliqué”“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 PreparationsThick smear Drop of blood on slide Water rinse to eliminate rbc’s Stain with Giemsa stain (not Wright-Giemsa) proper pH

Need the proper pH to stain the Schuffner’s granules

Concentrated to spot malaria parasites

Thin smear Feather edge smear For optimal morphology, stain with Giemsa (not Wright-Giemsa) stain with proper pH

Speciation of malaria Parasitemia (%)

Schuffner’s granules

P. ovale

Fimbriated edge

“Rosette” schizont

P. malariae

P. vivax

Amoeboid ring form

P.vivax – benign tertian malaria (fever every 48 hours), Duffy negative Red blood cell protects from Plasmodium invasion-African natives lack Duffy rbc antigen and this prevents them from P. vivax.Untreated infections last several years remaining dormant in the liver. Patients can survive years without treatment, but recurrent and chronic infection can lead to brain, kidney and liver damage

• P. falciparum-multiple ring forms per cell-accolade forms(ring forms on the edge of cell.-Banana gametocyte

Malignant tertian malariaBlack water fever

P. falciparum

High % parasitism

Accolade form

Banana gametocyte

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

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)

Other Protozoa - Toxoplasma

Toxoplasma gondii Coccidian protozoan House cat (kittens) = definitive host Infection from:

◦ Ingestion of infective oocysts from contaminated cat feces◦ Ingestion of improperly cooked meat from animals that serve as

intermediate hosts Symptoms

◦ Predilection for lung, heart, lymphoid organs, CNS/eye◦ Infectious mono-like; lymphadenitis, hepatitis, rash, encephalomyelitis,

myocarditis, chorioretinitis◦ Transplacental infection

◦ 1st trimester spontaneous abortion, stillbirth or severe disease◦ 2nd/3rd trimester CNS infections (epilepsy, encephalitis, intracranial

calcifications, MR, chorioretinitis, blindness, hearing loss), jaundice, rash◦ AIDS - Encephalitis; mass lesions in brain

Toxoplasma gondii Diagnosis

◦ Serology EIA◦ Anti-toxo IgM – congenital and acute infection; may persist

for months◦ Anti-toxo IgG – common; if positive, gestations safe from

intrauterine toxoplasmosis infection◦ PCR

Toxoplasma gondii

Toxoplasma gondii cyst Toxoplasma

in brain tissue stained tachyzoites

with hematoxylin and eosin

Free-living Amoeba Naegleria fowleri Acanthamoeba Balamuthia

Amoebic meningoencephalitis

Most common cause: Naegleria fowleri Granulomatous amoebic encephalitis or brain abscess: Acanthamoeba and Balamuthia

Clinical scenario: swimming or diving into fresh-water pools

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

◦ Take corneal scrapings◦ Visible trail of ameba moving across plate ingesting

E. coli

Wright’s stain

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

Nematodes Enterobius Ascaris Trichuris Necator and Ancylostoma (Hookworm) Microfilaria – Wucheria, Brugia, Loa loa, Mansonella, and Onchocerca

Enterobius vermicularis (pinworm)

Humans considered only host Females 8-13mm, males 2-5 mm Dwell in the cecum ¼-1/2 inch in thickness, white, lloks like string in stool

Lay up to 15,000 eggs◦ Oval with a flattened side: 50-60um by 20-30um

Diagnosis- Scotch tape test or anal swab Most common helminth in US

Enterobius vermicularis (pinworm) eggs

Asymmetrical eggs

Pinworm larvae -may be seen in stoolspecimens examined for pinworm

Eggs

Ascaris lumbricoides (roundworm)

1-1.2 billion people infected◦ More common in children

20,000 death Largest helminth to affect humans Females 20-35cm long, males 15-30cm with a curved tale◦ Can cause intestinal obstruction

Ascaris lumbricoides

Trichuris Trichiura (whipworm)

Soil transmitted Disease can can be similar to amebiasis PVA preserved samples inferior to formalin Adults attach to large intestine and are rarely recovered – diagnosis by detecting egg in stool specimens

Thinnest part- head Males are smaller than females

Trichuris trichiura

tail

Head

Necator americanus, Ancylostoma duodenale (Hookworms)

Soil transmitted 2nd most common helminth infection Enter via exposed skin

Necator or Ancylostoma – Hookworm egg

Strongyloides stercoralis

Soil transmitted Larval form only Presence of internal structures can separate from artifact In immune suppressed - massive intestinal infection and migration to the respiratory tract (eosinophilic pneumoniae) possible

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

Microfilariae Sheathed

◦ Wucheria bancrofti and Brugia malayi◦ Elephantiasis (lymphangitis/lymphedema)

◦ Loa loa◦ Calabar swellings & migrating worms in the conjunctiva

Not sheathed◦ Onchocerca volvulus◦ Mansonella species

◦ Allergic skin reactions, edema, Calabar swellings

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.

FilariaIdentification

a. W. bancrofti◦ Sheathed, nuclei stop short

of end of tail

b. B. malayi◦ Sheathed, two small nuclei

in tail

c. O. volvulus◦ Unsheathed, from skin, not

blood

d. Loa loa◦ Sheathed, nuclei to continue

to end of tail

Wucheria bancrofti

Brugia malayi

Loa loa

Mansonella perstans

Onchocerciasis

Black fly

Onchocerciasis

Trematodes (Flatworms) Intestinal and Liver flukes

◦ Fasciolopsis buski◦ Fasciola hepatica

Liver flukes◦ Clonorchis sinensis (Chinese liver fluke)

Paragonimus westermani – oriental lung fluke Schistosomes

◦ S mansoni – intestinal bilharziasis◦ S haematobium - urinary◦ S japonicum – blood fluke, found in intestines

Intestinal and liver flukes

Fasciolopsis buski Fasciola hepatica

The two most common intestinal flukes

Fasciola hepatica

Distinct nose

Fascioliasis is a parasitic infection typically caused by Fasciola hepatica, also known as "the common liver fluke" or "the sheep liver fluke. Fascioliasis is found in all 5 continents, especially where sheep or cattle are reared. Infected by eating raw watercress or other water plants contaminated with immature parasite larvae. The immature larval flukes migrate through the intestinal wall, the abdominal cavity, and the liver tissue, into the bile ducts, where they develop into mature adult flukes, which produce eggs. The pathology typically is most pronounced in the bile ducts and liver. Fasciola infection is both treatable and preventable

Intestinal fluke Fasciolopsis buski, causes fasciolopsiasis, is the largest intestinal fluke of humans. Prevented by cooking aquatic plants well before eating them. Found in south and southeastern Asia. Fasciolopsiasis is treatable. Many people do not have symptoms from Fasciolopsis infection. However, abdominal pain and diarrhea can occur 1 or 2 months after infection. With heavy infections Fasciolopsis flukes can cause intestinal obstruction, abdominal pain, nausea, vomiting, and fever.

Clonorchis sinensis

knobbin

Shouldersoperculates

Clonorchis is a liver fluke that can infect the liver, gallbladder and bile duct. Found across parts of Asia, it is also known as the Chinese or oriental liver fluke.

Egg is operculate, not embryonated, thick shell, asymmetrical and large

Paragonimus westermani

Paragonimus is a parasitic lung fluke (flat worm). Infections occur after a person eats raw or undercooked infected crab or crayfish. The illness is known as paragonimiasis. Paragonimus infection also can be very serious if the fluke travels to the central nervous system, where it can cause symptoms of meningitis.

Schistosoma mansonii

Schistosomiasis, also known as bilharzia, more than 200 million people are infected worldwide. In terms of impact this disease is second only to malaria as the most devastating parasitic disease.

The parasites that cause schistosomiasis live in certain types of freshwater snails. The infectious form of the parasite, known as cercariae, emerge from the snail, hence contaminating water. You can become infected when your skin comes in contact with contaminated freshwater. Most human infections are caused by Schistosoma mansoni, S. haematobium, or S. japonicum.

Stool or urine samples can be examined microscopically for parasite eggs (stool for S. mansoni or S. japonicum eggs and urine for S. haematobium eggs).

Cestodes (Tapeworms) Examples

Diphyllobothrium latum

Taenia saginata

Taenia solium

Hymenolepis nana

Hymenolepis diminuta

Echinococcus granulosis

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


Poorly-cooked fresh-water fish (salmon) Scandinavian, Russia, Canada, N. USA, Alaska Broad fish tapeworm Longitudinal sucker Eggs have non-shouldered operculum and knob

◦ They are not embryonated

Infection causes VitaminB12 deficiency

Sucking plate


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 by eating infected pork

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 diseasefound in Africa, Europe, Asia, the Middle East, and Central and South America. Highest prevalence is found in populations that raise sheep. Infection ingestion of egg found in animal feces.

Echinococcus – hydatid cyst

Short tapewormSand like materialcontained in the Cyst, due to inverted folded tapeworms

Relative size of Helminth eggs

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

Additional Insects of interest

MaggotsHouse fly larvae

Bot fly larvae

Bot fly bites human,Larvae develops andextrudes from the skin

Ticks of importance

Soft tick -Expands with bloodengorgement

Hard Ticks

Black Widow spider

Hour glassOn tummy

FleaBody louse

Crab louse

Hair nit

Scabies

Tiny

egg

s un

der s

kin

Mite

Parasitology Review 2017

Science

Transcript of Parasitology Review 2017