Diagnosis is made by examination of stool samples by light microscopy of stained smears (with iron hematoxylin or trichome) (Parasite Image Library; Suresh). Because fecal debris can be mistaken as a positive test, a permanent stained smear is preferred over a wet mount (Parasite Image Library). Endoscopy is not effective because it shows a normal-looking mucosa (Amin; Suresh). Stool culture methods (including an ELISA assay for detecting serum antibodies to B. hominis) are not routinely employed, though the technique is available. (Zierdt).
Indications for treatment are not established, particularly because the organism’s pathogenicity has not been recognized. Some experts recommend that treatment should be reserved for patients who have persistent symptoms and in whom no other pathogen or process is found to explain the gastrointestinal tract symptoms. Other experts believe that B. hominis does not cause symptomatic disease and recommend only a careful search for other causes of the symptoms
(Leder). However, Metronidazole, trimethoprim-sulfamethoxazole, and iodoquinol have been used with limited success (Pasqui, Blastocystis hominis Infection Fact Sheet). B. hominis is often a self-limiting infection, however, and response to specific treatment is erratic (Leelayoova).