Relapse of Paragonimus westermani lung infection after bithionol therapy.

Clinical trials of bithionol in treating Paragonimus westermani lung infection have been conducted in areas of endemic infection. Bithionol has been reported to cure over 90% of infected patients. We report a case of a 32-year-old Laotian man residing in Connecticut who relapsed with P. westermani pneumonitis 4 months after apparent eradication of infection with bithionol (40 mg/kg by mouth every other day for 10 doses). He was successfully treated with a second course of bithionol (40 mg/kg by mouth every other day for 15 doses). The mechanism of relapse of P. westermani infection following bithionol therapy should be evaluated.