Transmission electron micrograph (TEM) of a late trophozoite of the parasitic "Cryptosporidium parvum" showing two nuclei (in blue). This parasite causes severe diarrhea in humans, a condition known as cryptosporidiosis. It can be spread from person to person or from domestic animals to people. The symptoms include watery diarrhea lasting about a week; fever, nausea and abdominal pain. The infection is more severe in immune suppressed people, and is common in AIDS patients. Magnification = 25,000x. Enhancement of [9M9210].