This paper describes the etiological organism causing a new human infection, ie, Yan (also known as Morgellons) disease. Colored threads, black speck-like material, and granules are formed within and/or on the skin surface. The organism has four main morphological forms, ie, tube-shaped fibers, amorphous tuber masses, fibrous roots, and seeds. Brilliant red and blue autofluorescent pigments similar to phycobiliproteins have been observed. The seed form of the organism grows in solid potato and blood agar as pointed masses, and in potato broth as interconnecting bundles of fibers. The seed form of the organism was grown in a hamster/mouse model as light brownish tuber masses interconnecting with fibrous roots. The main symptoms for the patient are of biting, stinging, and a "shooting" sensation from the skin caused by the sharp and pointed ends of the seed form of the organism. Keywords: etiology, Morgellons, infectious, Brazil