Is paromomycin the drug of choice for eradication of Blastocystis in adults?

Blastocystis is a protozoan parasite of controversial clinical significance that is often detected in stools of patients with gastrointestinal complaints. Patients infected with Blastocystis and persistent, unexplained gastrointestinal complaints are often treated with the intention to eradicate Blastocystis. However, there is no consensus on the most effective drug. We performed a retrospective follow-up study with a large cohort of patients in which the natural disease course and efficacy of treatment with either paromomycin, clioquinol, or metronidazole were evaluated. With an eradication rate of 77 %, treatment with paromomycin appeared significantly more effective than treatment with clioquinol (38 %), metronidazole (38 %), or no treatment (22 %). This study showed that (1) Blastocystis was frequently observed in the stools of our patient group (34 %), (2) spontaneous clearance of Blastocystis infections occurred only in a small proportion of patients (22 %), and therefore (3) drug treatment is required for more efficient eradication of Blastocystis. Paromomycin exhibited superior performance in comparison to both metronidazole and clioquinol.