A case of refractory giardiasis successfully treated with paromomycin for cyst eradication

Abstract

A 45-year-old female commercial sex worker (CSW) presented with persistent diarrhea starting in late December of Year X. In March of Year X + 1, stool microscopy (O&P) identified Giardia intestinalis trophozoites and cysts. Although her symptoms initially resolved after a 10-day course of metronidazole (MNZ) at 1,500 mg/day, the diarrhea recurred one month later, and cysts were again identified in her stool. Since there had been no history of sexual activity from the completion of treatment until the recurrence of symptoms, a relapse of giardiasis was suspected.

As tinidazole was unavailable at our institution, paromomycin was administered at 1,500 mg/day for 10 days for the specific purpose of cyst eradication. One month after the completion of treatment, her clinical symptoms resolved, and follow-up stool examinations confirmed the disappearance of cysts. This case suggests that in nitroimidazole-refractory giardiasis where cysts persist, paromomycin can be an effective alternative treatment option. Clinical vigilance and parasite screening are essential for managing persistent diarrhea in high-risk populations, even in the absence of overseas travel history.