WEEK 4: PROTOZOAL DISEASES Flashcards
Define the following terms:
*Parasite
*Infection
*Infestation
*Definitive host
*Intermediate host
Parasite: An organism that spends a significant portion of its life in or on the living tissue of a host organism and causes harm to the host without immediately killing it.
Infection: invasion of endoparasites
Infestation: external parasitism of ectoparasites such as arthropods.
Definitive host: harbors the adult or sexual stage.
Intermediate host: part or all of the larval or asexual stage takes place
What are protozoa?
State physical characteristics of protozoa.
Means “first animal “.
They are esimplestandprimitiveof all animals.
- Unicellular eukaryotes:
*Lack cell wall,
*Contain membrane-bound organelles, including one or more nucleus. - Size ranges from 10–50um, some up to 1 mm, seen under a microscope.
- Body protoplasm is differentiated into an outerectoplasmand innerendoplasm.
- Locomotor organs are fingers likepseudopodia, whip-likeflagella, hair-likeciliaor none.
- Respiration occurs bydiffusionthrough the general body surface.
Protozoans exhibit mainly two forms of life.
State them.
Free-living(aquatic, freshwater, seawater)
Parasitic(ectoparasites or endoparasites)
List 3 ways in which protozoa obtain food.
How does excretion occur in protozoa?
What is encystment?
Why do protozoa do that?
Food obtained by:
*Absorption through the ectoplasm–diffusion /active transport
*Surround food and engulf it (phagocytosis)
openings or “cytostomes” into which they sweep food.
* Digest food intracellularly in stomach-like compartments - vacuoles
Excretion occurs through thegeneral body surface temporary opening in the ectoplasm or through a permanent pore call-CYTOPYGE.
Usually exists in the trophozoite or cystic stage.
Encystment- A process which goes on in protozoans, by which, the pseudopodia or other prolongations of the body being withdrawn, the animal assumes a spherical shape, and becomes coated with a comparatively tough resisting layer, which thus forms a cyst.
*To resist unfavorable conditions of food, temperature, moisture.
*Helps in dispersal.
*Non-feeding
*Non-motile
*Non-growing
What organism is described above?
Cyst
Protozoa reproduce asexually or sexually.
Describe the 2 ways of asexual reproduction.
Asexual reproduction by:
*Binary fission
*Schizogony
BINARY FISSION
-Nucleus divides into 2 parts
-Portions of cytoplasm then concentrate around each nucleus.
-Cell separates into 2 daughter cells.
SCHIZOGONY: multiple fission
-Nucleus undergoes multiple divisions
-Portions of cytoplasm then concentrate around each nucleus.
-Cell separates into multiple daughter cells.
State the sexual reproduction method of protozoa.
Sexual reproduction: Sporogony
Plasmodium
The life cycle is often complicated with alternation of asexual and sexual phases (alternation of generation).
Name the phylum in which plasmodium is found.
Phylum Apicomplexa
Give examples of the range of conditions resulting from protozoal infections, and the main types of organism responsible.
*Intestinal tract
*Urogenital tract
*Blood and tissue
- Entamoeba histolytica- Amoebiasis
Cryptosporidium spp.- Cryptosporidiosis
Cystoisospora belli- Isosporiasis
Cyclospora cayetanensis- Cyclosporiasis
Microsporidia- Microsporidiosis
Giardia intestinalis- Giardiasis
Balantidium coli- Balantidiasis - Trichomonas vaginalis- Trichomoniasis
3.
State 4 main types of protozoa that are the leading cause of death.
-Malaria
-Amoeba
-Toxoplasma
-Trypanosoma
Describe Entamoeba histolytica.
It exists in 2 forms. State them.
A pseudopod-forming nonflagellate amoebic protozoa
Move by means of flowing cytoplasm with the production of pseudopodia
Humans are the only host
Found in human colon
Exists in two forms-
*Cysts (formed stool) –infective form
*Trophozoites (diarrheal stools)
Both forms are passed in feces.
Cysts ingested from faecally contaminated food or water.
Sexual transmission through oral–anal sexual practices
State the Intestinal Amebiasis and its complications.
State Extraintestinal Amebiasis and its complications.
Asymptomatic Colonization
E. histolytica, E. dispar
Intestinal Amebiasis and Its Complications
-Amebic dysentery/ acute necrotizing colitis
-Ameboma
-Toxic megacolon
-Peritonitis
-Cutaneous amebiasis
-Rectovaginal fistulas
Extraintestinal Amebiasis
-Amebic liver abscess (hepatitis)
-Splenic abscess, Brain abscess, Empyema
-Pericarditis
State the lab diagnosis methods for Entamoeba Infection.
Lab diagnosis:
1.Microscopy
2.Antigen detection
3.Serologic tests
4.PCR
5.CT for abscess and granulomas
6.Colonoscopy
Treatment
*Luminal infection: iodoquinol, paromomycin, and diloxanide furoate
*Invasive amebiasis (colitis, liver abscess) *nitroimidazole -metronidazole and tinidazole
Describe the following free-living amoeba.
1. Acanthamoeba culbertsoni
2. Naegleria fowleri
3.Balamuthia mandrillaris
Acanthamoeba culbertsoni
Contaminated water
Keratitis, Uveitis in contact lens users.
Skin lesions – ulcers, hard nodules.
Granulomatous dissemination- lungs
Granulomatous necrotizing encephalitis.
Naegleria fowleri: Brain eating amoeba
Primary Amoebic Meningoencephalitis.
Fresh water
Balamuthia mandrillaris
Granulomatous amoebic encephalitis
From dust, soil
Transmission by inhalation, ingestion or skin injury
Give characteristics of Cryptosporidium.
Cryptosporidium parvum and Cryptosporidium hominis causes diarrheal disease - cryptosporidiosis.
Cryptosporidium oocysts in 87% of the raw water samples
Domesticated animals and birds - primary reservoir
AIDS patients and children excrete millions of oocysts a day, survive for months in sewage.
Spread by direct person-to-person contact.
The median infectious dose in healthy adult volunteers is 132 oocysts
Oocysts highly resistant to chlorination.
The hallmark of cryptosporidial infection is voluminous
watery diarrhea, explosive and foul smelling with abdominal cramps, fatigue, and anorexia.
