posted on 2021-07-23, 02:47authored byTM Kearns, R Speare, AC Cheng, J McCarthy, JR Carapetis, DC Holt, BJ Currie, W Page, Jennifer ShieldJennifer Shield, R Gundjirryirr, L Bundhala, E Mulholland, M Chatfield, RM Andrews
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. Clinical Trial Registration: Australian New Zealand Clinical Trial Register (ACTRN—12609000654257).
Funding
This work was supported by National Health and Medical Research Council (GTN0605804 - TMK RS ACC JM JRC DCH BJC WP EM RMA & GNT0545239 - TMK) https://www.nhmrc.gov.au/; Cooperative Research Centre for Aboriginal Health (HS331 - RMA) http://www.lowitja.org.au/; and Northern Territory Research Innovation Board and Fund (Grant round 6-2008 - TMK) http://www.bulletpoint.com.au/northern-territory-research-and-innovation-fund/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.