Blastocystis hominis has been associated with symptoms of bloating, flatulence, mild to moderate diarrhea, abdominal pain, and nausea. Because it has also been extensively documented in asymptomatic individuals, its pathogenicity remains debatable; most of the literature suggests that when B. hominis is identified in stool from symptomatic patients, other causes, such as Giardia lamblia and Cryptosporidium parvum, should be investigated before assuming that B. hominis is the cause (Blastocystis hominis Infection Fact Sheet). Recent literature proposes links between it and Irritable Bowel Syndrome (Yakoob), and researchers in Japan have detected elevated levels of B. hominis in individuals with intestinal obstruction due to carcinoma (Horiki; Leder).