Background Control of endemic scabies based on treatment of individual cases is difficult because of frequent re-infestation.
Methods A community intervention trial of mass drug administration (MDA) for scabies was undertaken to ascertain the efficacy and safety of two alternative regimens (topical permethrin and oral ivermectin MDA), compared with standard care. We identified three isolated island communities in Fiji and randomly assigned one of the three treatment regimens: ivermectin MDA, permethrin MDA or standard care with permethrin. All participants were sought for re-examination at 12 months, and 24 months via a 20% sample.
Results The study enrolled 2051 people. At baseline, scabies prevalence was high in all arms (32.1%, 41.7%, 36.6% in the three arms respectively). After one year the prevalence of scabies, fell to 1.9% in the ivermectin arm, a prevalence reduction of 94%.
At 24 months, At two years, scabies prevalence in the ivermectin arm was 3.7%, compared to 13.4% and 15.4% in both other arms.
The ivermectin MDA group, showed a relative reduction of 89% (95% CI 76-99, compared to 68% (52-81) in the permethrin MDA group and 59% (43-72) in the standard care group.
Impetigo prevalence at baseline was 21.6% in the standard care group and 24.6% in both MDA groups The relative reduction at 24 months was greatest in the ivermectin group at 90% (95% CI 74-99) compared to 64% (42-84) in the permethrin group, and 39% (15-61) in the standard care group. The difference between the permethrin and standard care groups was not statistically significant.
Conclusion, The effect of MDA on scabies , particularly with ivermectin, was long lasting, with very low prevalence maintained even after two years following administration. The effect on Impetigo was also encouraging, This strategy is likely to be highly beneficial for communities where this disease is endemic.