Any one (Host –parasite relatonships )

Associaton between organisms of two diferent species such as lichens

one benefts at the expense of the other, sometmes without killing the host organism

Example( Entamoeba coli) in the large intestne of man ,(one partner benefts but the other is not hurt

Parasites divided in general depending on:

habitat on the host and direct life cycle

Heteroxenous parasites :requiring at least three kinds of host
And direct life cycle

As to their dependence on host

An organism that cannot survive in any other manner and died without its host, such as Schistosoma and tape worm.

free- living state such as Strongyloides sp

It is obligatory parasites invade a stranger host such as Fasciola of sheep

According to their habitat on the host

Lives inside the systems and tssues of host body, mostly from helminthes.

visits the host for feeding only, such as mosquitoes

From mother to infant ex: Toxoplasmosis.

Trichomonas vaginalis

Elephantasis microflariae

Giarda lamblia, Trichomonas vaginalis, Trypanosoma spp, Leishmania spp

Cyst of Amoeboid is 10-60μm

The———— cyst has inclusions namely; glycogen mass and chromatoidal bars.

cyst wall of Amoebae is resistant to gastric juice

Most infectons are asymptomatc and the disease is diagnosed as