OVERVIEW OF
PROTOZOAL PATHOGENESIS
&
CLASSIFICATION
LEARNING OBJECTIVES
• At the end of the lecture the student should be able to:
– Know the general features of protozoa
– Enumerate the classification of protozoa
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THE PROTOZOA
Group ..Protos = first, Zoon = animal
Unicellular - eukaryotic microorganisms
Found in the kingdom protista
No common basic structure, size or shape
Size varies greatly- 2 to 5,000 micrometers
Distribution
– free living forms
– Parasitic forms (many animals carry protozoans as normal
flora)
– Factors affecting distribution of free living forms
• NaCl concentration
• pH
• Temperature
• Oxygen requirements
• NUTRITION
– Free living forms - phagocytosis of particulate matter
– Complex nutritional needs
– All are chemoheterotrophs
– Storage products - glycogen, starch and lipids
• REPRODUCTION
– Asexual – binary fission, multiple fission or budding
– Sexual - syngamy or conjugation
CLASSIFICATION (ORGANELLES OF MOTOLITY)
• Kingdom: protista
• Phylum : protozoa
• Groupings:
1. Amoeba
2. Flagellates
3. Ciliates
4. Sporozoa
AMOEBA - PSEUDOPODIA
• No cell wall
– Amoeba proteus - free living
amoeba
– Entamoeba histolytica
– Acanthamoeba sp.
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ENTAMOEBA HISTOLYTICA
Entamoeba histolytica is an anaerobic parasitic protozoan.
a single cell organism
divides by binary fission and can replicate in the intestinal tract,
primarily in the large intestine or colon
Bore their way into the bowel wall
cause ulcerations, severe bloody diarrhea called dysentery, and
abdominal pain
FLAGELLATES
Move by one or more flagella
Flagella (most human pathogens in this group)
– Most primitive of the protozoans
– Characteristics of flagella
Euglena and photosynthesis: Chloroplasts
Mutualism: in the gut of larger organisms
Parasitism: Giardia
PATHOGENIC FLAGELLATES
• Giardia lamblia
• Trichomonas vaginalis
• Trypanosoma sp
EUGLENA Sp.
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CILIATES
Most advanced of the
protozoa
Oral groove
Contractile vacuole
Nuclear dimorphism
Reproduction
Asexually by binary
fission
Sexually by
conjugation
Pathogenic ciliate –
balantidium col
SPOROZOA
• All obligate
intracellular parasites
• All have complex life
cycles
• Pathogenic
sporozoanplasmodium sp.
• Causative agent of
malaria
• Four species cause
malaria
1. P. MALARIAE
2. P. OVALE
3. P. VIVAX
4. P. FALCIPARUM
LIFE CYCLE
• Occurs in two organisms
– MOSQUITO (ANOPHELES sp.) And human body
– Sexual cycle in mosquito
– Asexual cycle in human body
• 3 important stages in life cycle
– Sporozoite
– Merozoite
– Gametocyte
• Life cycle of plasmodium
TREATMENT
• Treatment for protozoan infections is usually an antibiotic called
metronidazole also called flagyl.
REFERENCES
• MEDICAL MICROBIOLOGY BY JAWETZ
25th EDITION
Page # 2-6-665
THANK YOU