Parasitology

• Classification: The parasites of humans are classified within:

• 1. Protozoology = study of protozoa (primitive single cells)

• 2. Helminthology = study of helminths (worms) including

• multicellular parasites with organs (also known as metazoa)

• 3. Entomology = study of arthropods (insects).

Protozoa

Classification of pathogenic protozoa according to the site of

infection Site of infectionSpecies

Intestinal tract Amoeba

* Entamoeba histolytica

Intestinal flagellates

* Giardia lamblia

Intestinal ciliate *Balantidium coli

Urogenital tractUrogenital flagellate

* Trichomonas vaginalis

Blood and tissueHemoflagellates * Trypanosoma sp, Leishmania sp.

Blood Sporozoans * Plasmodium sp.

Tissue Sporozoans *Toxoplasma gonidii

Questions form for Protozoa

• Type of protozoan (amoeba, ciliate, flagellate:intestinal or blood & tissue, sporozoan)

• Disease caused by protozoan• Infective stage• Lab diagnosis (diagnostic stage)• Form of protozoan under the microscope• Vector for the protozoan• Location (site of infection) of the protozoan in

the body

Intestinal protozoa (General life cycle)

• Entamoeba histolytica• Balantidium coli

ingestion(food, water...)

In large intestine (Ent., B. coli)Excystation

Trophozoite

pass in feces

mature cyst

encyst

Multiply

Entamoeba histolytica

• Type of protozoan: amoeba

• Disease caused by protozoan:amoebic dysentery

• Infective stage:cyst

• Diagnostic stage: Cyst or trophozoite in stool

• Forms of the protozoan:trophozoite or cyst

• Location in the body: large intestine

Entameba histolytica trophozoite

Entameba histolytica cyst

Balantidium coli

• Type of protozoan: ciliate• Disease caused by the protozoan:

Balantidial dysentery• Infective stage: cyst• Lab diagnosis(diagnostic stage):

trophozoite or cyst in stool• Forms of the protozoan: trophozoite or

cyst• Location in the body: large intestine

Balantidium coli trophozoite

Urogenital flagellate

• Trichomonas• vaginalis• Type of protozoan: urogenital flagellate• Disease caused by protozoan: Trichomoniasis• Infective stage: trophozoite• Form of protozoan: Trophozoite only. No cyst• Location in the body: urogenital tract of male

(urethra and prostate) and female (vagina)• Diagnostic stage: trophozoite in vaginal swab or

prostate secretion

Hemoflagellates

• Trypanosoma sp.• Leishmania sp.• Forms of

Hemoflagellates

according to the

Position of organ

Of locomotion

Amastigote has no

Free flagellum

Trypanosoma cruzi

• Type of protozoan:hemoflagellate• Disease caused by the protozoan: Chagas

disease• Infective stage:Metacyclic trypomastigote• Form of the protozoan under

microscope:trypomastigote in blood film• Vector of the protozoan: Bug (Triatoma)• Location of the protozoan in the body: blood and

tissue(heart muscle, liver ,spleen, brain)• Diagnostic stage: Trypomastigote in blood film

• Trypomastigote in blood film

Leishmania sp.

• Type of the protozoan: hemoflagellate• Disease caused by the protozoan: Leishmaniasis

(visceral, cutaneous or mucocutaneous)• Infective stage:Promastigote• Vector of the protozoan: Sand fly• Form of the protozoan under the microscope: amastigote

(leishmania bodies) released from macrophage• Location in the body: blood& tissue• Diagnostic stage: Amastigote (leishmania body) released

from macrophage in tissue.

Amastigote released from macrophage

Blood sporozoans

• Plasmodium sp

Plasmodium vivax

Plasmodium malaria

Plasmodium falciparum

Plasmodium ovale

Plasmodium sp.

• Type of protozoan: blood sporozoan• Disease caused by the protozoan: Malaria• Infective stage:sporozoite in the saliva of female

Anopheles mosquito• Form of the protozoan under microscope:Different

stages of the Plasmodium sp. in red blood cells• Vector of the protozoan: Female anopheles mosquito• Location of the protozoan in the body: blood • Lab diagnosis (diag stage) Different stages of the

Plasmodium sp. in red blood cells in blood film

Arthropods

• Class Insecta:flea, louse, bed bug, mouth parts of female Anopheles mosquito

• Class Arachnida: hard tick, mites

• Class Crustacea: Cyclops

• Question form: Medical importance

Flea

• Medical importance:

• Vector of plague

• Intermediate host for H.diminuta, D. caninum

• Transmit endemic typhus or murine typhus

Bed bug

• Medical importance:

• Insomnia, irritation

Bed bug

Louse

• Medical importance:

• Pediculosis

• Could transmit trench fever and epidemic typhus

Louse

Mouth parts of Female Anopheles mosquito

• Medical importance: transmit malaria

Female Anopheles mosquito

Hard tick

• Medical importance:

• Mechanically: bite, bleeding

• Systemically: tick paralysis

• Could transmit rocky mountain spotted fever

Hard tick

Mite

• Medical importance: Sarcoptes scabei mite cause scabies

Mite

Cyclops (male and female)

Medical importance:

• Intermediate host for: Diphylobothrium latum, Diphylobothrium mansoni, Dracunculus medinensis

Cyclops