general info on protozoans

protozoan charcateristics

• microscopic

• single cell - unicellular eukaryotes

• widely dispersed in all enviroments

• heterotrophic

protozoan main groups

• intestinal

• blood and tissue

different ways protozoans can move around

amoeboid movement

flagella

cilia

non-motile

amoeboid movement

movement achieved by extension of pseudopodia

flagella movement

whiplike appendages that propel the organism

cilia movement

numerous, hair-like structures used for movement

non-motile protozoans

cant move, lack specialized locomotor structures

fulminating infection by protozoans

protozoans can multiply quickly in the host causing serious disease and pathology

parasitic protozoans can evade/escape the host’s immune system by

Antigenic Variation

Intracellular Residence

antigenic variation

parasite can change the antigens expressed on its surface, makes it difficult for the host’s immune system to adapth and defend against the parasite.

intracellular residence

parasite enters and lives within one of the host cells

amoeba epidemeology

endemic in US

ciliate epidemeology

endemic in US

flagellate epidemiology

some endemic  / some exotic

sporozoite epidemiology

all exotic

general life cycle types in protozoans

• direct transmission

• fecal/oral transmission

• vector-borne transmission

• predator/prey transmission

direct transmission

intimate body contact → sexual intercourse

organism never leaves host

fecal/oral transmission

usually through environmentally resistant cyst

cyst getting into food and water

vector-borne transmission

blood sucking arthropods infected/pass on the organisms to hosts

predator/prey transmission

parasite in prey tissue, predator gets infected

general life cycle stages

• trophozoite form

• cyst form

cyst form

protective covering secreted by the parasite to safeguard it for survival

trophozoite form

multiplication stage for protozoans

also the stage where they feed and grow

how do protozoans multiply

binary fission

what are the main types of cysts

• protective

• reproductive

protective cyst

protects the organism, no internal changes

reproductive cyst

protects and allows the nuclei of the protozoan to multiply

triggers of the cyst form

excess or reduced food

excess waste product

desiccation (drying out)

changes in oxygen

changes in temperature