Species of colorless algae of the genus Prototheca are recently being recognized as pathogens. Five human cases have been identified, three of them not previously reported. Algae are capable of growing in the skin, subcutaneous tissue, bursal sacs, and lymph nodes of man. Immunologic impairment was demonstrable in only one of the five patients.
Tindall JP, Fetter BF. Infections Caused by Achloric Algae (Protothecosis). Arch Dermatol. 1971;104(5):490-500. doi:10.1001/archderm.1971.04000230032005