What Are Intestinal Parasites?
Human intestinal parasites are either one-cell organisms or intestinal worms that live in the small or large intestine and use the stool or blood from intestinal wall as a source of food.
One-Cell Parasites – Protozoa
One-cell organisms, like Giardia lamblia, also called Giardia duodenale (Picture 1), Cryptosporidium (crypto) and Cyclospora, utilize nutrients from the stool. They belong to a living kingdom Protozoa (Gk. protos = first; zoa = animals). They may cause inflammation of the small intestine thus hampering absorption of nutrients. Entamoeba hystolytica lives predominantly in the colon.
Picture 1. Parasite giardia from a stool sample,
as seen under the electron microscope (actual size:~0.01 mm)