Introduction and Protozoa

Define parasitism

one individual living at the expense of another

What are parasites to their hosts?

to some degree metabolically dependent

What is a direct lifecycle?

Only one species of host

What is the name for parasites that follow a direct lifestyle?

Monoxenous parasites

What is an indirect lifecycle?

Hosts of different species

What is the definitive most?

Where the parasite reaches sexual maturity

What is the intermediate host?

required for development but not the site of sexual maturity

What are the 2 types of resting stages of protozoans?

cysts or spores

Where are protozoan parasites found?

intra or extracellular

What are protozoans similar to?

metazoan cells (multicellular animals)

Do protozoans reproduce sexually or asexually?

both

How do protozoans reproduce asexually

binary fission

How do protozoans reproduce sexually

conjugation

two protozoans fuse briefly and exchange DNA

What is the “false foot” of the protozoa called?

pseudopod

What is protozoa gliding?

actin + myosin act to pull

the front (apex) releases lubricant proteins

Which protozoans typically glide?

Apicomplexa

What is the most prevalent protozoan parasite

Giardia

What are giardia resistant to?

chlorine treatment

What can giardia pass through?

advanced membrane filters

Where do giardia attach?

small intestine

What are the two life forms of giardia

trophozite (food animal) and cyst

What is the large portion of the Giardia trophozite surface called?

ventral disc

What is the shape of the Giardia trophozite

pear shaped

Describe the structure of the Giardia trophozoite

Two nuclei, 4 pair of flagella, 2 median bodies

Describe the structure of the Giardia cyst

4 nuclei and oval shaped

What is the life cycle of Giardia

direct

How do Giardia infect hosts?

pingestion of cysts in contaminated goods

What triggers excitation of Giardia

gastric acid during passage through stomach

What triggers encytation of Giardia

exposure to bile salts and ph 7.8

Where are cysts of Giardia shed from the host to?

Feces

What is the causative agent of tyoxoplasmosis?

Toxoplasma gondii

Why is Toxoplasma gondii so successful?

Can infect all warm blooded animal cells

Cysts can survive inside immune cells

What is the survivable temperature range of toxoplasma gondii?

12-65

What individuals are particularly at risk from toxoplasmosis?

foetus

immuno-comprimised

sea mammels and marsupials

What can toxoplasmosis do to the intermediet host?

behavioural changes

What is the definitive host of toxoplasmosis?

felines

What is the intermediate host of Toxoplasma gondii?

any nucleated mammalian or avian cell?

virtually any warm-blooded animal

Describe how toxoplasma gondii cysts exit a feline?

undeveloped cysts exit and becomes infectious in the envrioment (sporogony)

Where does Toxoplasma gondii replicate?

asexual multiplication occurs in the intermediate host

Whats a Tachyzoites

the fast multiplying phase of a protozoan parasite

Whats a bradyzoite?

A persistant cyst

How does Toxoplasma gondii infect foetus?

transplacental

What transmits malaria?

female mosquitoes

Where does maleria develop?

hepatocytes and red blood cells of humans

What are hepatocytes?

liver cells

What is the causative agent of maleria?

plasmodium

What is the lifecycle of plasmodium

indirect

What are thw two hosts of plasmodium (maleria)

female mosquitoes

humans

What is the specific species of mosquitoes which carry plasmodium as the definative host?

Anopheles