Invasive Blastocystis hominis Infection in a Child

The association ofBlastocystis hominiswith human disease is controversial. Many studies1-9have reported its association with gastrointestinal symptoms such as diarrhea, abdominal cramps, vomiting, and weight loss. Other reports10,11doubt its clinical pathogenicity. To our knowledge, invasive B hominis has not been found in humans. We describe a patient whose biopsy specimen was positive forB hominiscolonic ulceration, which produced rectal bleeding and protein-losing enteropathy. Patient Report.A previously healthy 4-year-old girl was hospitalized with a 3-week history of rectal bleeding. The illness started with blood-streaked stools, which progressed to watery stools, five to six times a day, and blood clots. There was no history of abdominal pain, fever, nausea, vomiting, lethargy, decreased appetite, or prior antibiotic treatment. One week before admission to Texas Children's Hospital (Houston), she was seen in another hospital for fever and watery diarrhea with blood streaks. The results of the diagnostic