Lecture1 Protozoa

8/9/2019 Lecture1 Protozoa

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Clinical Parasitology

Tropical Medicine

International Health

www.medicine.mcgill.ca/tropmed


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ParasitologyClinical parasitology

Tropical Disease

Epidemiology

International Health

MicrobiologyClinical microbiology

Infectious Disease

Epidemiology

Public Health


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Institute of Parasitology, MacDonald Campus

McGill Centre for Tropical Disease, MGH

Department of Microbiology, Lyman Duff

International Health Office, Dept of Epidemiology


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Protozoa

Nematode

Cestode

Trematode


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Kingdom Animalia

Subkingdom Protozoa

Phylum Sarcomastigophora

Phylum Apicomplexa

Phylum Ciliophora

Phylum Microspora

Subkingdom MetazoaPhylum Nematoda

Phylum Platyhelminthes

Taxonomy


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Intestinal protozoa


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Kingdom Animalia

Subkingdom Protozoa

Phylum Sarcomastigophora

Subphylum Sarcodina Entamoeba

Subphylum Mastigophora GiardiaPhylum Apicomplexa malaria

Phylum Ciliophora Balantidium

Phylum Microspora microsporidium

Taxonomy


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Mastigophora: movement with flagella - e.g. Trichomonas,Giardia

Sarcodina: pseudopodia, e.g. Entamoeba histolytica

Apicomplexa: apical complex, no locomotor apparatus;sexual reproduction, e.g. cryptosporidium,

malaria, toxoplasma

Ciliophora: movement with cilia, e.g. Balantidium.


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INTESTINAL PROTOZOA

Pathogenic

Entamoeba histolytica

Balantidium coli

Giardia lamblia Dientamoeba fragilis

Cryptosporidium parvum

Enterocytozoon bieneusiSeptata intestinalis

Cyclospora cayetanensis

Isospora belli

Commensal

Entamoeba hartmani

Entamoeba dispar

Entamoeba coli Endolimax nana

Iodamoeba bütschlii

Chilomastix mesniliTrichomonas hominis

Blastocystis hominis


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Trophozoite: any stage in a protozoan’s life cycle

which can ingest food. In practice also

refers to the motile form.

Cyst: the non motile form which is protected by

a distinct membrane or cyst well. This is

an infective stage of the parasite.

Excystation: the process of emergence of the

trophozoite from the cyst (vs.

encystation)

Pseudopod: literally means false foot; temporary

cytoplasmic processes at the surface of

the trophozoite


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Intestinal protozoa


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(amoebiasis)

Subphylum sarcodina


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Entamoeba histolytica trophozoite with ingested RBCs


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Epidemiology of Entamoeba histolytica

Man the only source (not a zoonosis)

Fecal-oral transmission

Our understanding is in transition

because of mis-identified cases.

Seen in travellers, Saskatchewan native population


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AMOEBIASIS

1) assymptomatic carrier state

2) acute amoebic dysentry

3) amoebic liver abscess

4) amoeboma


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AMOEBIC LIVER ABSCESS

Presentation

1. persisting fever

2. RUQ or epigastric pain and/or shoulder pain3. rarely diarrhea

Diagnosis1. ultrasound

2. raised WBC

3. serology4. aspirate microscopy

5. response to metronidazole 750 t.i.d.


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Laboratory problems

1. sensitivity

2. specificity


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Sequential Stool Examination for E. histolytica

93 %88796541direct, concentration

and stain

69 %61513821direct andconcentration

50 %43342513direct

54321


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Cogwheel distribution of chromatin and central karyosome

Entamoeba . histolytica


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Entamoeba histolytica/dispar

E. histolytica E. dispar (antigen capture, PCR, culture and zymodemes)


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Drugs for Entamoeba histolytica

Tissue: ..metronidazole, tinidazole, secnidazole, ornidazole

..emetine..dehydroemetine

..chloroquine

Bowel lumen: ..paromomycin (Humatin)

..diiodochlorhydroxyquin (Diodoquin)

..diloxanide furoate (Furamide)


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Giardia lamblia

Subphylum mastigophora


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Normal

small intestine mucosa


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Villus atrophy

Crypt hyperplasia


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Giardia epidemiology:- faecal oral spread

- prevalence 3-5% in Canada; increased intravellers, backpackers, institutions, day

care centres- zoonosis - found in most mammals; esp.

beaver (“beaver fever”), cattle, cats,dogs, etc.

GIARDIASIS


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GIARDIASIS

Symptomsdiarrhea

flatulence

abdominal cramps

decreased appetite

+ weight loss

+ nausea

no fever

Signsmild abdominal

tenderness

Laboratoryno leukocytes in

stool

no mucous in stool

giardia cystsintermittent in stool

giardia cysts induodenal aspirate


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3-5 microns


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CRYPTOSPORIDIUM

Epidemiology: - bovine reservoir

- epidemic contamination of

municipal water

Biology: - lives in small intestine epithelialcell membrane

- Apicomplexa life cycle

Clinical: - diarrhea 2-3 weeks (chronic in

AIDS)- cholecystitis


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Taxonomy: Apicomplexa

Epidemiology: in travellers to tropics (Nepal, Americas): raspberries from Guatemala

Biology: lives in small intestine epithelial cells

Clinical: prolonged diarrhea (2-6 wks)

Treatment: Septra


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Treatment of intestinal protozoa


Giardia

Cryptosporidium

Cyclospora

metronidazole

diloxanide furoate

diodohydroxyquinoline

metronidazole

atabrine

nil

Septra


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INTESTINAL PROTOZOA STAINS

1. Hematoxylin - E. histolytica, Giardia,

D. fragilis, Isospora

2. Modified Ziehl-Neelsen - Cryptosporidium

Cyclospora

3. Trichrome - Microsporidium

Trichomonas vaginalis


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g

Taxonomy: Mastigophora

Epidemiology: reservoir is human

urogenital tract

Biology: causes inflamation ofvaginal and urethral epithelium

Clinical: vaginal discharge

Treatment: metronidazole


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Your present understandingcommensalism

zoonosis

Your future challenges

1. Host immunological reaction to protozoa2. The protozoan’s host immune avoidance

3. Laboratory diagnostic tools PCR, antigen capture,

proteomics4. Orphan drugs

5. Lack of Cryptosporidium treatment

Lecture1 Protozoa

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