Mass administration of ivermectin may decrease prevalence of scabies and impetigo

1. Mass administration of ivermectin decreased the prevalence of scabies and impetigo in Fiji over the course of a year.

2. Mild adverse events were more frequent in the ivermectin group.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Scabies, the skin condition caused by Sarcoptes scabiei var. hominis, is a public health concern in developing countries such as Fiji. This is because infestation is associated with stigma and impetigo, which can lead to complications systemically. Given that reinfestation may be common in countries where scabies is endemic, it would be timely to determine if mass drug administration may be helpful in decreasing prevalence of this disease. This study conducted a trial of mass drug administration for scabies control in Fiji to determine its impact on the prevalence of scabies and impetigo over a year.

There was a significant decrease in scabies prevalence in the standard care, permethrin and ivermectin groups. However, the greatest reduction was seen in the ivermectin group with a relative reduction rate of 94%. The prevalence of impetigo also declined in all study groups, with the greatest relative reduction of 67% in the ivermectin group. Mild adverse events were reported and occurred most frequently in the ivermectin group. Strengths of this study include trialing a novel means to help reduce scabies infestation. Limitations include not undergoing a true cluster-randomized controlled trial where multiple communities would be assigned to each treatment group.

Click to read the study, published today in NEJM

Relevant Reading: Impaired quality of life in adults and children with scabies from an impoverished community in Brazil

In-Depth [randomized controlled trial]: This trial randomly assigned three island communities in Fiji to three treatment regimens. These included standard care whereby infected individuals and their contacts were given permethrin, mass administration of permethrin or mass administration of ivermectin. These three communities were chosen for their relative isolation and population size to provide study power. Each community had one nurse-staffed clinic. The primary outcome of interest was change in the prevalence of scabies or impetigo over 12 months.

A total of 2051 people, over 85% of the population of the three communities, participated in the study. The prevalence of scabies reduced significantly in all three treatment groups as compared to baseline. In the standard care group there was a decrease from 36.6% to 18.8% (relative reduction in prevalence 49%; 95% [CI] 37-60), the permethrin group had a decrease from 41.7% to 15.8% (relative reduction 62%; 95% [CI] 49 to 75) and from 32.1% to 1.9% in the ivermectin group (relative reduction 94%; 95% CI 83 to 100). It is thought that the reason for a reduction in the standard care group was increased access to care during this study period. Impetigo prevalence rates also decreased across all treatment groups, with relative reductions of 32%, 54% and 67% for the standard care, permethrin and ivermectin groups respectively. Common adverse events were itching and headache and they were more common in the ivermectin group than the permethrin.

Image: PD/CDC

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