Life cycle

Protozoa of the genus Entamoeba have two stages: the infectious cyst and the disease-producing trophozoite. Infection occurs directly from person to person, by the faecal-oral route; transmission occurs by insects and food. Cysts survive in contaminated food, water, and vegetables. The cysts pass the stomach and excyst in the small intestine. The emerging trophozoites migrate to the colon where interactions with the mucosa causes functional and morphological damage. Encystation occurs in the large intestine, apparently as a result of interactions

Page 96

with the altered environment, including the presence of the bacterial flora. Infectious cysts are excreted with the stools. In acute amoebic diarrhoea, trophozoites are also excreted.

0 0

Post a comment