Final answer:
Entamoeba histolytica is a protozoan causing amoebic dysentery, existing as cysts and trophozoites. Infection can lead to severe intestinal illness and possibly liver abscesses, treated typically with antibiotics like metronidazole.
Step-by-step explanation:
Entamoeba histolytica is a protozoan parasite that causes amoebiasis, also known as amoebic dysentery in its severe form. This organism is capable of existing in two forms: as a cyst and as a trophozoite. The cyst form is the infectious stage that can survive in the environment and is typically ingested via fecally contaminated water or food. These cysts can cause infection with as few as 10 being transmitted. Once inside the host, the cysts transform into the trophozoites, which are the active, multiplying form of the parasite.
Trophozoites can cause tissue damage and may lead to the formation of liver abscesses in infected individuals. Entamoeba histolytica belongs to the supergroup Amoebozoa, organisms that move using pseudopodia. A related but less pathogenic species is Entamoeba dispar, which does not cause disease. Diagnosis of an E. histolytica infection is often made using a stool ova and parasite (O&P) exam under a microscope. Treatment typically involves antibiotics such as metronidazole. Preventative measures include proper sanitation and avoiding contaminated food and water.