<unk>  ( or ) is a genus of anaerobic flagellated protozoan parasites of the phylum Metamonada that colonise and reproduce in the small intestines of several vertebrates, causing the disease<unk> sis. Their life cycle alternates between a swimming trophozoite and an infective, resistant cyst.<unk>  were first described by the Dutch microscopist Antonie van Leeuwenhoek in 1681. The genus is named after French zoologist Alfred Mathieu Giard.
Giardia
Cryptosporidium
Salmonella
Entamoeba histolytica
Shigella
Faecalibacterium
Cheyletiella
Entamoeba coli