Philippe Gaxotte

Treatment of Strongyloides stercoralis infection with ivermectin compared with albendazole: results of an open study of 60 cases

Ivermectin is highly effective against animal intestinal nematodes and is used in the treatment of onchocerciasis in humans. A study was undertaken to compare the efficacy of the drug with that of albendazole in the treatment of uncomplicated strongyloidiasis. Sixty patients with confirmed Strongyloides stercoralis infection were enrolled in an open randomized study and given either albendazole, 400 mg/d for 3 d or ivermectin, 150-200 micrograms/kg in a single dose. Efficacy and tolerance were evaluated on days 7, 30 and 90. Each visit included a parasitological examination of 3 stool specimens, using saline and Kato smears and formalin-ether and Baermann concentrations. Fifty-three patients were eligible for evaluation. Parasitological cure was obtained in 24 of the 29 patients treated with ivermectin (83%) and in 9 of the 24 patients who were given albendazole (38%); ivermectin was significantly more effective than albendazole (P < 0.01). Clinical and biological adverse reactions were negligible in both treatment groups. The 20 patients who failed therapy were given a second treatment course with 150-200 micrograms/kg of ivermectin in a single dose or on 2 consecutive days. Sixteen patients were cured and the other 4 had only incomplete follow-up. Ivermectin therefore constitutes an acceptable therapeutic alternative for uncomplicated strongyloidiasis.

DOUBLE-BLIND STUDY OF IVERMECTIN AND DIETHYLCARBAMAZINE IN AFRICAN ONCHOCERCIASIS PATIENTS WITH OCULAR INVOLVEMENT

In a randomised double-blind study, ivermectin was compared with diethylcarbamazine (DEC) and placebo in the treatment of onchocerciasis in 30 male patients from Mali with moderate to heavy Onchocerca volvulus infections and ocular involvement. 10 patients received a single oral dose of ivermectin, 12 mg, 10 received DEC daily for eight days (total dose 1.3 g), and 10 received matching placebo. Patients were examined periodically for twelve months. Punctate keratitis disappeared in 6 of 7 ivermectin patients but increased in DEC patients. Numbers of O volvulus microfilariae (mf) in the anterior chamber decreased slowly and eventually disappeared in most ivermectin patients during the six months following treatment; anterior chamber mf disappeared more rapidly in some patients after DEC, but reappeared within six months of stopping treatment. Both ivermectin and DEC caused a prompt decrease in mean skin mf density; density then increased in both groups over the twelve month observation period, reaching 9% of pretreatment values in ivermectin patients and 45% in the DEC group. Analysis of adult O volvulus from nodules excised at three and twelve months post treatment showed no effect of either drug on viability; however, there was evidence of degeneration of intra-uterine developing mf in the ivermectin group. Side-effects were less frequent and less severe in ivermectin patients than in DEC patients. Ivermectin as a single oral dose appears to be a more effective microfilaricidal drug than DEC in onchocerciasis.

A double-blind comparison of the efficacy and safety of ivermectin and diethylcarbamazine in a placebo controlled study of Senegalese patients with onchocerciasis.

Ivermectin (MK-933) has been compared with diethylcarbamazine (DEC) and placebo in a double-blind study in 30 adult male Senegalese patients with Onchocerca volvulus infection. 10 patients were randomly assigned to each treatment group. Ivermectin was administered as a single oral dose of 12 mg and DEC as 50 mg daily for two days and 100 mg twice daily for the following six days, total 1.3 g in eight days. Skin O. volvulus microfilaria densities remained near pre-study values in the placebo patients, but decreased rapidly with both active drugs to mean values about 2% of pretreatment (Day 8) and then increased slowly, reaching in 12 months about 4% of pre-treatment (ivermectin) and 18% (DEC). This difference is statistically significant. Clinical adverse reactions were recorded in four ivermectin, ten DEC and three placebo patients. One ivermectin and six DEC patients received steroid treatment for relief of these reactions. Serious adverse ocular changes were not seen in any patients, possibly because of the steroid therapy in the DEC patients. Adult O. volvulus from onchocercal nodules one and six months after treatment showed no effect of either drug on viability. Intra-uterine developing forms of the microfilariae appeared normal in all three treatment groups at the one month examination but deformed and degenerated forms were evident at six months in the ivermectin group but not in the DEC and placebo patients. Ivermectin as a single oral dose appears to be a safer and more effective microfilaricidal drug in human onchocerciasis than DEC in the standard multi-dose regimen.

Ivermectin and filariasis

Ivermectin, a parasiticide that long ago proved its worth in veterinary medicine, became one of the most effective tools for control programs against human filarial diseases in the 1980s. It is provided at no cost, is effective against microfilariae (blocking their transmission) and can be administered annually as a single oral dose with virtually no side‐effects: these considerations led the WHO to officially declare eradicable two endemic filarial diseases (among the major endemic diseases worldwide), onchocerciasis and lymphatic filariasis.

Reduced Loa loa microfilaria count ten to twelve months after a single dose of ivermectin

The action of a single dose of ivermectin (200 micrograms/kg) on 71 Gabonese patients with Loa loa microfilariae in the peripheral blood, and living in areas highly endemic for loiasis, has been evaluated. Ten to 12 months after treatment, 43 patients (63%) had no circulating microfilaria and the geometric mean peripheral blood microfilaria count had decreased by 88.6% (P < 0.02). Thus, a single annual dose of ivermectin can markedly reduce loiasis transmission.