Ancient Cambrian fossils have preserved the oldest known example of parasites in action. More than 500 million years ago in what is now southern China, tubelike parasites clung to the shells of tiny ...

Researchers have analyzed drinking water and detected oocysts of Cryptosporidium and cysts of Giardia, two protozoa that cause outbreaks of diarrhea in humans. The levels detected are very low and do ...

A parasite is an organism that lives in or on an organism of another species. Three main classes of parasites can cause disease in humans: protozoa, helminths, and ectoparasites. Protozoa and ...

DURING recent years, there has been increasing amount of evidence regarding the importance of protozoa in the aerobic purification of sewage 1–4 and, more recently, some quantitative observations on ...