Gastrointestinal tract: cryptosporidiosis and HIV

Cryptosporidiosis: Cryptosporidium parvum, a diarrhoea causing parasite. This is a transmission electron micrograph of a section of duodenum. The image shows a Cryptosporidium parvum trophozoite (left) and a meront (right). Three merozoites are seen in the meront. At the base of both the trophozoite and the meront the electron-dense feeding disc is the interface between the parasite and the host cell cytoplasm. The patient was HIV-positive and presented with diarrhoea.