The most commonly reported symptoms are nonspecific: nausea, mild
diarrhea, vomiting, flatulence, and abdominal cramping. Fever, weight
loss, and stools with blood, mucus, or leukocytes are uncommon.
The ability to cause invasive disease is controversial. Controlled
studies fail to confirm a true pathogenic role, although this confusion
may be attributed to pathogenic and nonpathogenic ribodeme types,
similar to Entamoeba histolytica and E
dispar.5 However, it is also difficult
to generate valid control groups, because most stools submitted
are obtained from symptomatic patients. Identification of B
hominis by trichrome staining is complicated by the organism’s
great morphological diversity. Other diagnostic approaches used
to detect the organism in human stool (indirect fluorescent antibody and,
more recently, polymerase chain reaction6,7) or
host serological response (ELISA) are not readily available.