Is the treatment of Enterobius vermicularis co-infection necessary to eradicate Dientamoeba fragilis infection?

OBJECTIVES: Dientamoeba fragilis is a pathogenic protozoan of the human gastrointestinal tract with a worldwide distribution, which has emerged as an important and misdiagnosed cause of chronic gastrointestinal illnesses such as diarrhea and 'irritable-bowel-like' gastrointestinal disease. Very little research has been conducted on the use of suitable antimicrobial compounds. Furthermore, higher rates of co-infection with Enterobius vermicularis have been described, suggesting that E. vermicularis could influence the treatment of D. fragilis-infected patients. To study this, the treatment of E. vermicularis and D. fragilis co-infected patients was evaluated.

METHODS: Forty-nine patients with a D. fragilis infection, including 25 (51.0%) patients co-infected with E. vermicularis, were studied. All of them were treated with metronidazole. Patients with E. vermicularis co-infection and/or an E. vermicularis-positive case in the family were treated with mebendazole.

RESULTS: Metronidazole treatment failure was significantly more frequent in patients with E. vermicularis co-infection and in patients with children in the family.

CONCLUSIONS: Co-infection with E. vermicularis may act as a factor favoring D. fragilis infection by preventing eradication measures. This suggests that both parasites should be treated simultaneously.