Efficacy and safety of ivermectin and thiabendazole in the treatment of strongyloidiasis

Treatment of strongyloidiasis has been traditionally based on thiabendazole, despite its frequent gastrointestinal side effects and failure to achieve eradication of the parasite from faeces in approximately 30% of cases. Ivermectin has been shown to be more effective for treating chronic uncomplicated strongyloidiasis. The efficacy and tolerability of these drugs in a series of patients treated from 1999 to 2002 at the Oliva Health Centre, Valencia, Spain, are reported. A total of 88 patients diagnosed of strongyloidiasis were treated using the following regimens: thiabendazole 25 mg/kg/12 h for 3 consecutive days in 31 patients; ivermectin 200 mug/kg as a single dose in 22 patients; and ivermectin 200 mug/kg for 2 consecutive days in 35 patients. The efficacy and side effects were recorded. A total of 65 patients were male, and 23 female. The mean age was 64 +/- 12 years. Of the patients, 44 had worked barefoot in rice fields. Among the 31 patients treated with thiabendazole, 25 (78%) met the criteria for cure (the absence of parasite in faeces after examination of three samples collected on alternate days), and 5 (16%) experienced side effects (asthenia, epigastralgia and disorientation). Of the 22 patients treated with ivermectin on a single day, 17 (77%) met the criteria for cure, and 2 (9%) reported side effects (dizziness, dyspepsia). Among the 35 patients treated with ivermectin on 2 consecutive days, 100% met the criteria for cure, and 0% experienced side effects. In chronic uncomplicated strongyloidiasis, a treatment regimen consisting of ivermectin 200 mug/kg for 2 consecutive days provided the best results with regard to efficacy and tolerability. When the eosinophilia continued after treatment, we observed a high percentage of not-cure rate (7 of 9 patients, 77%).