General Parasitology and Protozoa
The infective form of Entamoeba histolytica is:
a. Quadri or tetranucleate cyst is the infective stage of E. Histolytica.
b. The cysts can survive for weeks or months in wet environments, though are easily killed by heat or freezing temperatures. When the cysts are ingested the cyst extrudes a trophozoite with four nuclei. This divides into four trophozoites, and the nuclei or each of these divides to lead to eight initial trophozoites.
c. Source of infection: cyst passing patient/ asymptomatic carrier.
d. Transmission: contaminated food, water