Impact of an Ivermectin Mass Drug Administration on Scabies Prevalence in a Remote Australian Aboriginal Community

Therese Kearns, R Speare, Allen Cheng, James McCarthy, Jonathan Carapetis, Deborah Holt, Bart Currie, Wendy Page, Jennifer Shield, Roslyn Gundjirryirr Dhurrkay, Leanne Bundhala Dhurrkay, Edward Kim Mulholland, Mark Chatfield, Ross Andrews

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Abstract

BACKGROUND: Scabies is endemic in many Aboriginal and Torres Strait Islander communities, with 69% of infants infected in the first year of life. We report the outcomes against scabies of two oral ivermectin mass drug administrations (MDAs) delivered 12 months apart in a remote Australian Aboriginal community.

METHODS:
Utilizing a before and after study design, we measured scabies prevalence through population census with sequential MDAs at baseline and month 12. Surveys at months 6 and 18 determined disease acquisition and treatment failures. Scabies infestations were diagnosed clinically with additional laboratory investigations for crusted scabies. Non-pregnant participants weighing ≥15 kg were administered a single 200 μg/kg ivermectin dose, repeated after 2-3 weeks if scabies was diagnosed, others followed a standard alternative algorithm.

PRINCIPAL FINDINGS:
We saw >1000 participants at each population census. Scabies prevalence fell from 4% at baseline to 1% at month 6. Prevalence rose to 9% at month 12 amongst the baseline cohort in association with an identified exposure to a presumptive crusted scabies case with a higher prevalence of 14% amongst new entries to the cohort. At month 18, scabies prevalence fell to 2%. Scabies acquisitions six months after each MDA were 1% and 2% whilst treatment failures were 6% and 5% respectively.

CONCLUSION:
Scabies prevalence reduced in the six months after each MDA with a low risk of acquisition (1-2%). However, in a setting where living conditions are conducive to high scabies transmissibility, exposure to presumptive crusted scabies and population mobility, a sustained reduction in prevalence was not achieved.
Original languageEnglish
Article numbere0004151
Pages (from-to)1-13
Number of pages13
JournalPLoS Neglected Tropical Diseases
Volume9
Issue number10
DOIs
Publication statusPublished - 2015

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Kearns, T., Speare, R., Cheng, A., McCarthy, J., Carapetis, J., Holt, D., Currie, B., Page, W., Shield, J., Dhurrkay, R. G., Dhurrkay, L. B., Mulholland, E. K., Chatfield, M., & Andrews, R. (2015). Impact of an Ivermectin Mass Drug Administration on Scabies Prevalence in a Remote Australian Aboriginal Community. PLoS Neglected Tropical Diseases, 9(10), 1-13. [e0004151]. https://doi.org/10.1371/journal.pntd.0004151