Life Cycles

Question 1

Entamoeba

Answer 1

Mature quadrinucleated Cysts - infective form

Ingestion of contaminated food and water
stomach - by passed-cyst wall resistant to gastric juice
SI- digested by trypsin -
LI -Excystation in caecum or terminal ileum
Cyst liberates tetranucleate amoeba—8 amoebulae( metacystic trophozoite)

Amoebulae— motile— penetrating epithelium of mucous membrane— dissolve intestinal epithelial cells with proteolysis

Burrow deeper by cytolysis till they reach submucous coat
Lodge in submucous tissue of LI (normal habitat) mutiply by binary fission

Destroy tissues , Utilize cytolysed material as food, Submucosa destroyed
Abscess break down— Development of ulcers

Trophozoites discharged into lumen— Encystation— Cysts — excreted in Feces— ingested by another host and cycle repeated

Question 2

Taenia solium/ saginata

Answer 2

Adult worm in SI — liberates eggs or gravid segments with fasces
Animals (Pigs/ cows / buffalo) — swallows these eggs while grazing on fields
In alimentary canal —Eggs wall rupture and oncosphere liberated— penetrate gut wall by hooks— portal— lymphatics— systemic circulation
via portal veins— reach liver heart lungs muscle

Naked oncosphere — filter out from bld to muscles(tongue shoulder neck hands cardiac muscle)
Oncosphere lose hooks, cells liquefied 8 days after infection,
Oncosphere forms oval vesicle ( increasing in size,containing larva ( scolex or future head of adult worm) at bottom = cysticercus
60-70 days for oncosphere metamorphosis into cysticercus

Humans infected when ingested undercooked beef/ pork containing cysticerci ( measly beef/ pork)
Inside alimentary canal of man, scolex ( contact with bile and exvaginate) anchors to gut walls by suckers— developed into adult worm by gradual strobilisation
Worms— sexually mature in 2-3 months and produce eggs— feces — cycle repeated