Which organism is responsible for causing amoebiasis?

The organism responsible for causing amoebiasis is Entamoeba histolytica. This protozoan parasite infects the human intestinal tract and can lead to various gastrointestinal symptoms, including diarrhea, abdominal pain, and in severe cases, dysentery. Entamoeba histolytica is unique among its peers as it can invade the intestinal lining and even spread to other organs, such as the liver, leading to amoebic liver abscesses.

Entamoeba histolytica is distinguished from the other organisms listed, which have different roles in infectious diseases. For instance, Giardia lamblia primarily causes giardiasis, a condition characterized by diarrhea due to another type of protozoan. Cryptosporidium parvum is another protozoan that leads to cryptosporidiosis, also resulting in gastrointestinal symptoms. Ascaris lumbricoides is a helminth (worm) responsible for ascariasis, presenting a very different infection mechanism and clinical manifestation related to intestinal blockage and nutrient absorption issues.

Understanding the specifics of the organisms and their associated diseases is critical in differentiating between these parasites and recognizing the primary causative agent of amoebiasis, which is specifically linked to Entamoeba histolytica.