Parasitic amoeba (Entamoeba histolytica), illustration - stock illustration

Parasitic amoeba (Entamoeba histolytica) engulfing red blood cells, computer illustration. This single-celled organism causes amoebic dysentery and ulcers (vegetative trophozoite stage). It is spread by faecal contamination of food and water and is most common where sanitation is poor. Amoebae invade the intestine but may spread to the liver, lungs and other tissues. Infection is caused by the ingestion of cysts that develop into the pathogenic trophozoite amoeba seen here. Entamoeba histolytica occurs worldwide, with up to 50% of the population being infected primarily in warmer climates.