Sappinia is a free-living ameba, or amoeba* (a single-celled living organism), found in the environment. There are two known species of Sappinia: Sappinia diploidea and Sappinia pedata. This ameba causes amebic encephalitis, which is an infection of the brain. Worldwide, only one case of amebic encephalitis due to Sappinia infection has been reported.
*About the Term "Ameba"
In U.S. English, the single-celled living organism described here is an ameba. The word amoeba, with an "o", is used as part of a scientific genus name (such as Amoeba or Acanthamoeba). In British English, both the generic organism term and genera names are spelled amoeba with an "o".
There is no universal definition of a "rare disease" but the U.S. Rare Disease Act of 2002 defined a rare disease as affecting less than 200,000 people in the U.S. and this definition has been adopted by the National Institutes of Health, Office of Rare Diseases.