1. Background

• Blastocystis hominis is acquired either directly or indirectly
• an asymptomatic carrier state is well documented and therefore the relationship of B. hominis to symptoms remains controversial
• immunosuppressed patients are more likely to be symptomatic

1. Diarrhea

• mild to moderate

2. Associated Symptoms

• abdominal pain
• bloating
• flatulence
• nausea and vomiting
• postprandial abdominal distention
• weight loss

1. Stool

• B. hominis is recovered from 1-20% of stool samples submitted for ova and parasite
• the presence of 5 or more organisms/hpf suggests heavy infection and is correlated with symptoms
• no WBC's or blood
• B. hominis is often found in stool samples where other pathogens are detected, i.e., Giardia, Cryptosporidium

2. Blood

• eosinophilia

1. Supportive

• B. hominis often disappears without therapy
• symptoms may be self-limiting or last for months

2. Medical

• indications for medical therapy have not been established
• may be used to treat immunocompromised symptomatic patients
• use either Metronidazole or Iodoquinol

1. 1997 Red Book, p. 153.