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Randomized Controlled Trial
. 2020 Jul;103(1_Suppl):14-23.
doi: 10.4269/ajtmh.19-0829.

Impact of Different Mass Drug Administration Strategies for Gaining and Sustaining Control of Schistosoma mansoni and Schistosoma haematobium Infection in Africa

Affiliations
Randomized Controlled Trial

Impact of Different Mass Drug Administration Strategies for Gaining and Sustaining Control of Schistosoma mansoni and Schistosoma haematobium Infection in Africa

Charles H King et al. Am J Trop Med Hyg. 2020 Jul.

Abstract

This report summarizes the design and outcomes of randomized controlled operational research trials performed by the Bill & Melinda Gates Foundation-funded Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) from 2009 to 2019. Their goal was to define the effectiveness and test the limitations of current WHO-recommended schistosomiasis control protocols by performing large-scale pragmatic trials to compare the impact of different schedules and coverage regimens of praziquantel mass drug administration (MDA). Although there were limitations to study designs and performance, analysis of their primary outcomes confirmed that all tested regimens of praziquantel MDA significantly reduced local Schistosoma infection prevalence and intensity among school-age children. Secondary analysis suggested that outcomes in locations receiving four annual rounds of MDA were better than those in communities that had treatment holiday years, in which no praziquantel MDA was given. Statistical significance of differences was obscured by a wider-than-expected variation in community-level responses to MDA, defining a persistent hot spot obstacle to MDA success. No MDA schedule led to elimination of infection, even in those communities that started at low prevalence of infection, and it is likely that programs aiming for elimination of transmission will need to add supplemental interventions (e.g., snail control, improvement in water, sanitation and hygiene, and behavior change interventions) to achieve that next stage of control. Recommendations for future implementation research, including exploration of the value of earlier program impact assessment combined with intensification of intervention in hot spot locations, are discussed.

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Conflict of interest statement

Trials registration: The studies discussed in this article are registered at International Standard Randomised Controlled Trial registry (http://www.isrctn.com/). Identifiers: ISRCTN99401114 (Côte d’Ivoire Sustaining Control Study (Sm1)), ISRCTN14849830 (Kenya Sustaining Control Study (Sm1)), ISRCTN16755535 (Kenya Gaining Control Study (Sm2)), ISRCTN14117624 (Mozambique Gaining Control Study (Sh2)), ISRCTN95819193 (Tanzania Gaining Control Study (Sm2)), and ISRCTN32045736 (Niger annual versus biannual treatment study).

Data availability: Data collected in SCORE studies will be housed and made accessible to the global research community through Clinical Epidemiology Database Resources, ClinEpiDB (https://clinepidb.org/ce/app/) at the University of Pennsylvania. Data will be available as anonymized individual participant data with an accompanying data dictionary in early 2020.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the U.S. Centers for Disease Control and Prevention or of the World Health Organization.

Figures

Figure 1.
Figure 1.
Study arms and timeline for the Schistosomiasis Consortium for Operational Research and Evaluation studies of gaining and sustaining control of schistosomiasis in sub-Saharan Africa. CDI = Côte d’Ivoire; CWT or C = community-wide treatment; H = drug holiday—a year when no praziquantel mass drug administration was provided; SBT or S = school-based treatment.
Figure 2.
Figure 2.
Revised study design for Schistosomiasis Consortium for Operational Research and Evaluation’s Niger Schistosoma haematobium control studies. CWT or C = community-wide treatment; H = drug holiday—a year when no praziquantel mass drug administration (MDA) was provided; SBT or S = school-based treatment; x1 = one MDA per year in years 3 and 4; x2 = two MDAs per year in years 3 and 4.
Figure 3.
Figure 3.
Overall prevalence, by infection categories of light, moderate, and heavy intensity categories at Year 1 (baseline; Y1) and Year 5 (study endpoint; Y5) in the Schistosomiasis Consortium for Operational Research and Evaluation gaining and sustaining control studies. The study arms indicated are detailed in Figure 1. CDI = Côte d’Ivoire; C = community-wide treatment; H = drug holiday—a year when no praziquantel mass drug administration was provided; KEN = Kenya; MOZ = Mozambique; S = school-based treatment; TAN = Tanzania.
Figure 4.
Figure 4.
Mean community-level infection intensity in Schistosoma mansoni eggs per gram feces, or S. haematobium eggs per 10 mL urine at Year 1 (baseline; Y1) and Year 5 (study endpoint; Y5) in the Schistosomiasis Consortium for Operational Research and Evaluation gaining and sustaining control studies. The study arms indicated are detailed in Figure 1. CDI = Côte d’Ivoire; C = community-wide treatment; H = drug holiday—a year when no praziquantel mass drug administration was provided; KEN = Kenya; MOZ = Mozambique; S = school-based treatment; TAN = Tanzania.
Figure 5.
Figure 5.
Impact on prevalence of four consecutive years of school-based treatment (SSSS) on 9–12-year-old and first-year schoolchildren in Schistosomiasis Consortium for Operational Research and Evaluation sustaining control studies. Baseline (Y1) and endpoint (Y5) prevalence of Schistosoma mansoni infection intensity categories are shown. Asterisks denote statistically significant differences between baseline and endpoint values at a P < 0.05 level by χ2 testing. CDI = Côte d’Ivoire; KEN = Kenya; NS = not significant.
Figure 6.
Figure 6.
Impact on prevalence of four consecutive years of school-based treatment (SBT or SSSS) or four consecutive years of community-wide treatment (CWT or CCCC) on 9–12-year-old and first-year schoolchildren in Schistosomiasis Consortium for Operational Research and Evaluation gaining control studies. Baseline (Y1) and endpoint (Y5) prevalence of Schistosoma mansoni or Schistosoma haematobium infection intensity categories are shown. Asterisks denote statistically significant differences between baseline and endpoint values at a P < 0.05 level by χ2 testing. KEN = Kenya; MOZ = Mozambique; NS = not significant; TAN = Tanzania.
Figure 7.
Figure 7.
Impact of four consecutive years of school-based treatment (SBT or S; Arm 4) or four consecutive years of community-wide treatment (CWT or C; Arm 1) on 9–12-year-old children and adults in Schistosomiasis Consortium for Operational Research and Evaluation gaining control studies. Baseline (Y1) and endpoint (Y5) prevalence of Schistosoma mansoni infection intensity categories are shown. Asterisks denote statistically significant differences between baseline and endpoint values at a P < 0.05 level by χ2 testing. KEN = Kenya; MOZ = Mozambique; NS = not significant; TAN = Tanzania.
Figure 8.
Figure 8.
Outcomes of the Schistosomiasis Consortium for Operational Research and Evaluation Niger annual vs. biannual treatment trial. Shown are the starting (Y1) and ending (Y5) prevalences of heavy and light Schistosoma haematobium infections in communities that received treatment under the revised Niger study protocol. Studies A (in communities with microhematuria prevalence 5–20% in eligibility testing) and B (communities with microhematuria prevalence > 20% in eligibility testing) began with annual or every-other-year school-based treatment, whereas Study C (communities with prevalence > 20% in eligibility testing) began with annual community-wide treatment during the first 2 years. Each study group was then randomized to receive annual or twice-yearly praziquantel treatments; creating groups A1, A2, B1, B2, C1, and C2 (see Figure 2 for details). The difference in Y5 outcome was significant between groups B1 and B2 (P = 0.037). Differences in final prevalence outcomes for studies A and C were not statistically significant.

References

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