1. VIII. Protozoan Diseases
A. Basic Properties of Protozoa
B. Amebiasis
C. Primary Amebic Meningoencephalitis
D. Giardiasis
E. Trichomoniasis
F. Balantidiasis
G. Toxoplasmosis
H. Malaria
I. Cryptosporidiosis
J. Pneumocystosis

2. VIII. A. Basic Properties of Protozoa
Cellular properties
Eukaryotic microorganisms having animal-like cells
No cell walls
Most have heterotrophic metabolisms
A few protozoa (eg Euglena) are photosynthetic

3. VIII. A. Basic Properties of Protozoa
Cellular properties (cont.)
Many are free-living in soil or aquatic environments; a few are parasitic
Single-celled or simple colonial organization
Classification based predominately on the mechanism of motility

4. VIII. A. Basic Properties of Protozoa
Classification
Class Sarcodina
Motile by pseudopodia & amoeboid movement
Amebas, radiolaria, and foraminifera
Examples:
Amoeba
Entamoeba histolytica
Naegleria fowleri

5. VIII. A. Basic Properties of Protozoa
Classification (cont.)
Class Mastigophora
Motile by flagella
Examples:
Euglena
Giardia lamblia
Trichomonas vaginalis

6. VIII. A. Basic Properties of Protozoa
Classification (cont.)
Class Ciliophora
Motile by cilia
Examples:
Paramecium
Balantidium coli

7. VIII. A. Basic Properties of Protozoa
Classification (cont.)
Class Sporozoa
A class of parasitic protozoa
Most have complex life cycles with both sexual & asexual stages
Adult forms are nonmotile
Examples:
Plasmodium
Toxoplasma gondii

8. VIII. A. Basic Properties of Protozoa
“Trophozoite” and “Cyst”
Some protozoa go through different stages in their life cycle.
This is especially true of certain parasitic protozoa.
Trophozoite: Actively growing and reproducing stage
Cyst: A dormant stage, enclosed in a resistant cyst coat

9. VIII. B. Amebiasis Cause: Entamoeba histolytica
A parasitic ameba; class Sarcodina
Transmitted via contaminated food & water
Cysts are shed in the feces
When ingested: Excystation occurs in the intestine
Trophozoites grow & reproduce in the intestinal tract

10. VIII. B. Amebiasis Symptoms Abdominal pain
Little diarrhea but often blood in the stool (“amebic dysentery”)
Possibly of intestinal ulceration; perforation; infection of internal organs such as liver & lungs

11. VIII. C. Primary Amebic Meningoencephalitis
Cause: Naegleria fowleri
A fresh water, free living ameba
No cyst stage
Several cases of infections in swimmers
Transmission and Symptoms:
Transmission through the nasal & sinus passages
Infection of the brain & meninges
Headaches; delirium; seizures

12. VIII. D. Giardiasis Cause: Giardia lamblia
A flagellate of class Mastigophora
The trophozoite has four pairs of flagella & two nuclei; giving it a face-like appearance
Grows in the intestinal tract
Cysts are shed in the feces

13. VIII. D. Giardiasis Transmission and Symptoms
Transmitted via contaminated water & food
Foul-smelling profuse diarrhea
Sometimes chronic
Often misdiagnosed
Diagnosis via microscopic examination
Enterotest capsule

14. VIII. E. Trichomoniasis Cause: Trichomonas vaginalis
Flagellate of the class Mastigophora
No cyst stage
Transmission & Symptoms
Transmitted via sexual contact
Genital itching
Painful urination with a white, mucoid discharge
Occasional reduction of sperm count or erosion of the cervix

15. VIII. F. Balantidiasis Cause: Balantidium coli Transmission & Symptoms
Ciliated, in Class Ciliophora
Trophozoites grow in the intestinal tract
Cysts are shed in the feces and may remain embedded in intestinal walls, causing chronic infections
Transmission & Symptoms
Contaminated water & food
Ulceration in intestines
Profuse diarrhea

16. VIII. G. Toxoplasmosis Cause: Toxoplasma gondii In Class Sporozoa
Both asexual & sexual stages
Invasion of several areas of the body, including internal organs & muscle tissue
Possibly the most prevalent protozoan parasite of humans

17. VIII. G. Toxoplasmosis Transmission & Symptoms
Transmitted via eating contaminated meat
Cysts are found in the meat, especially of grazing animals such as cattle
Cats can transmit the disease through their feces
Lymph node swelling; flu-like symptoms

18. VIII. G. Toxoplasmosis Transmission & Symptoms (cont.)
Generally mild in non-immunosuppressed persons
Severe infections in immunosuppressed persons
Pregnant women are in danger of fetal damage or miscarriage

19. VIII. H. Malaria Cause: Plasmodium species In Class Sporozoa
Complex life cycle requiring two hosts: a mammal (human) and the mosquito Anopheles

20. VIII. H. Malaria Transmission and Symptoms
The asexual merozoite stage infects human blood from the bite of a mosquito
The parasite invades erythrocytes & reproduces
Erythrocytes break open & release the parasite; this causes the characteristic fever, chills, anemia, weakness, hemorrhaging
Intense fever & chills about hr after exposure, due to the simultaneous rupture of so many erythrocytes

21. VIII. H. Malaria Transmission and Symptoms (cont.)
The sexual stage of Plasmodium develops in the human host and is picked up by a mosquito
The sexual stage is completed in the salivary gland of the mosquito to complete the cycle
Treatment by quinine & other antimalarial drugs

22. VIII. I. Cryptosporidiosis
Cause: Cryptosporidium species
In class Sporozoa
A common protozoan parasite in humans
Transmission and Symptoms
Contaminated water
Mild diarrhea in non-immunosuppressed persons
Severe diarrhea in immunosuppressed persons

23. VIII. J. Pneumocystosis Cause: Pneumocystis carinii
Usually classified as a protozoan of class Sporozoa, but recent evidence suggests that it may be a fungus
Transmission and Symptoms
Transmitted by airborne contact
Usually asymptomatic or with mild respiratory symptoms
Causes severe pneumonia in immunocompromised persons
A major secondary infection & cause of death in AIDS patients