Scabies and Impetigo Prevalence After Ivermectin/Azithromycin Mass Drug Administration

Reported scabies coverage 3 years after a round of ivermectin and azithromycin mass drug coadministration was over 95% for the first dose and over 80% for the second, suggesting coverage with 2-dose ivermectin-based mass drug administration may have a large and sustained effect on disease prevalence, according to a study published in Clinical Infectious Diseases.

There is a need for evidence to inform control intervention guidelines now that the World Health Organization has designated scabies as a neglected tropical disease. Although ivermectin-based mass drug administration is a promising strategy for the control of scabies and impetigo in areas where these diseases are endemic, current follow-up data for most studies are limited to 12 months. Longer term data are needed. This survey-based study evaluated the prevalence of impetigo and scabies 3 years after a single round of mass drug coadministration with ivermectin and azithromycin in 10 province villages in the Solomon Islands. Prevalence at 36 months was compared with prevalence at baseline.

Of the 1210 study population, scabies prevalence at 36 months was 4.7% (95% CI, 3.6-6.1), a rate significantly lower than the rate seen at baseline (18.7%; relative reduction 74.9%; 95% CI, 61.5%-87.7%; P  <.001). Impetigo prevalence was 9.6% (95% CI, 8.1%-11.4%); this rate was also significantly lower than the rate seen at baseline (24.7%; relative reduction 61.3%; 95% CI, 38.7%-100%; P <.001). The highest scabies prevalence was seen in children under 5 years (12.5%; adjusted odds ratio 33.2; 95% CI, 6.6-603.2), and the highest impetigo prevalence was seen among children aged 5 to 9 years (16.4%; adjusted odds ratio 8.1; 95% CI, 3.6-21.8).

Study investigators concluded that the study, “was non-randomised and performed in a relatively isolated island population, but despite these limitations it represents a significant contribution to the emerging data on the use of ivermectin-based [mass drug administration] for the control of scabies, providing further support for adoption of this intervention as the central component of global scabies control efforts.”

Ivermectin for this study was provided at a reduced cost by Merck Sharp & Dohme Australia.

Reference

Marks M, Romani L, Sokana O, et al. Prevalence of scabies and impetigo three years after mass drug administration with ivermectin and azithromycin [published online May 25, 2019]. Clin Infect Dis. doi: 10.1093/cid/ciz444