Objective: To investigate whether praziquantel is effective against diphyllobothriasis nihonkaiense at doses less than the conventional dose.
Patients and methods: Fourteen Japanese men with diphyllobopthriasis nihonkaiense were treated with a single administration of praziquantel at 5-10 mg/kg.
Results: Twelve patients expelled a complete integrated Diphyllobothrium nihonkaiense with its scolex. One patient expelled an integrated D. nihonkaiense without its scolex, and one patient expelled 2 complete integrated D. nihonkaiense with their scolex, and an integrated D. nihonkaiense without its scolex. The lack of eggs in stool samples was confirmed in these 2 patients after the end of therapy. All patients had not expelled proglottides after the end of therapy for more than 1 year. No side effects were identified in any of the patients.
Conclusion: All patients were considered to be cured. Our results indicate that the oral administration of a single dose of praziquantel at 5-10 mg/kg is effective and safe against D. nihonkaiense infections.