Description
Blastocystis is an enteric protozoan parasite of humans and a variety of other animals. It has a worldwide distribution and is often the most commonly isolated organism in parasitological surveys. Early studies associated Blastocystis infections with symptoms such as abdominal pain, diarrhea, constipation, fatigue, headaches, and depression. Subsequent reports added skin rash and joint pain to the list. The Center for Disease Control (CDC) states that the symptoms reported to be associated with Blastocystosis infection are diarrhea, watery or loose stools, anal itching, abdominal pain, weight loss, and excess gas (CDC Fact Sheet). This wide array of non-specific symptoms has confounded the understanding of the potential pathogenicity of Blastocystis species. As a result, many of these infections likely go undiagnosed. Detection of Blastocystis is routinely performed by methods such as microscopy, culture, and formyl acetate concentration technique (FECT). Yet, these methods all have flaws that make them unreliable or time consuming. Since Blastocystis has several morphological forms (vacuolar, cyst, amoeboid, granular, multivacuolar, and avacuolar), microscopy is very difficult. In addition, FECT is unreliable because it destroys the multivacuolar, vacuolar, and granular forms of the parasite during stool processing. Culture requires 2-3 days to diagnosis and in some instances allows preferential growth of one subtype over another if more than one subtype is present in the stool. Nevertheless, microscopy and culture are believed to be the "gold standard" methods for detection of Blastocystis