The effects of ivermectin on onchocercal skin disease and severe itching: results of a multicentre trial

Abstract

Summaryobjective To determine the effects of ivermectin in annual, 3-monthly and 6-monthly doses on onchocercal skin disease (OSD) and severe itching.method A multicentre, double-blind placebo controlled trial was conducted among 4072 residents of rural communities in Ghana, Nigeria and Uganda. Baseline clinical examination categorized reactive skin lesions as acute papular onchodermatitis, chronic papular onchodermatitis and lichenified onchodermatitis. Presence and severity of itching was determined by open-ended and probing questions. Clinical examination and interview took place at baseline and each of 5 subsequent 3-monthly follow-up visits.results While prevalence and severity of reactive lesions decreased for all 4 arms, those receiving ivermectin maintained a greater decrease in prevalence and severity over time. The difference between ivermectin and placebo groups was significant for prevalence at 9 months and for severity at 3 months. Differences between placebo and ivermectin groups were much more pronounced for itching. From 6 months onward, the prevalence of severe itching was reduced by 40-50% among those receiving ivermectin compared to the trend in the placebo group.conclusion This is an important effect on disease burden as severe itching is for the affected people the most troubling complication of onchocerciasis. The difference among regimens was not significant, and the recommended regimen of annual treatment for the control of ocular onchocerciasis appears also the most appropriate for onchocerciasis control in areas where the skin manifestations predominate. The final determination of the effect on skin lesions requires a longer period of study. keywords onchocerciasis, ivermectin, onchodermatitis, itching correspondence W. R. Brieger,

Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections

“…Hence, we applied a relationship between the prevalence of troublesome itch and of adult female worms, previously derived using ONCHOSIM [25,26]. Troublesome itch was related to the presence of female adult worms because the association between the presence of mf and troublesome itch does not hold during ivermectin treatment, the reduction in prevalence of itch being smaller and more delayed than the drop in microfilarial prevalence and load [25,26,53]. This relationship is subject to considerable uncertainty and so it was varied in the sensitivity analysis (Table  3).…”

Research for control: the onchocerciasis experience*

“…Now that the importance of skin disease had been demonstrated, there was a need to further clarify the effectiveness of ivermectin treatment in OSD and to determine the most appropriate treatment interval as it had been suggested that annual treatment might not be adequate for OSD and that treatment may need to be given as often as every 3 months (Burnham 1995). A multicentre double-blind placebo-controlled trial was undertaken, which showed that ivermectin treatment resulted in a significant reduction in itching and reactive skin lesions during the first year after treatment and that there was no difference between 3-monthly, 6-monthly and annual treatment regimens (Brieger et al 1998a). Hence, the annual treatment regimen was accepted for all endemic areas, including those with the 'forest' strain of the parasite.…”

Temporal recruitment of neutrophils and eosinophils to the skin in a murine model for onchocercal dermatitis.

“…2,3 The impact of onchocercal skin disease on both the health of infected individuals and on the economy of the local communities is significant. 1,[3][4][5][6] In addition, onchocercal skin disease is a focus of the African Program for Onchocerciasis Control. 3,4 In the current study, we used a murine model that reproduces clinical and histologic features of early stage onchocercal skin disease to examine underlying pathogenic mechanisms.…”