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Parasit Vectors. 2015 Oct 22;8:529. doi: 10.1186/s13071-015-1144-3.

Modelling control of Schistosoma haematobium infection: predictions of the long-term impact of mass drug administration in Africa.

Author information

1
Department of Mathematics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio, USA. dxg5@case.edu.
2
Department of Mathematics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio, USA. nxy47@case.edu.
3
Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio, USA. yel3@case.edu.
4
Department of Epidemiology, Yale School of Public Health, 60 College Street, New Haven, Connecticut, USA. martial.ndeffo-mbah@yale.edu.
5
Department of Epidemiology, Yale School of Public Health, 60 College Street, New Haven, Connecticut, USA. david.durham@yale.edu.
6
Schistosomiasis Control Initiative, Imperial College, Norfolk Place, St Mary's Campus, London, UK. a.phillips05@imperial.ac.uk.
7
Schistosomiasis Control Initiative, Imperial College, Norfolk Place, St Mary's Campus, London, UK. valdoaurelio1@yahoo.com.br.
8
Universidade Catholica de Moçambique, Beira, Mozambique. josefoferro@yahoo.com.br.
9
Department of Epidemiology, Yale School of Public Health, 60 College Street, New Haven, Connecticut, USA. alison.galvani@yale.edu.
10
Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio, USA. chk@cwru.edu.
11
Schistosomiasis Consortium for Operational Research and Evaluation, University of Georgia, Athens, Georgia, USA. chk@cwru.edu.

Abstract

BACKGROUND:

Effective control of schistosomiasis remains a challenging problem for endemic areas of the world. Given knowledge of the biology of transmission and past experience with mass drug administration (MDA) programs, it is important to critically evaluate the likelihood that MDA programs will achieve substantial reductions in Schistosoma prevalence. In implementing the World Health Organization Roadmap for Neglected Tropical Diseases it would useful for policymaking to model projections of the status of Schistosoma control in MDA-treated areas in the next 5-10 years.

METHODS:

Calibrated mathematical models were used to project the effects of different frequency and coverage of MDA for schistosomiasis haematobia control in present-day endemic communities, taking into account uncertainties of parasite biology and input data. The modeling approach in this analysis was the Stratified Worm Burden model developed in our earlier works, calibrated using data from longitudinal S. haematobium control trials in Kenya.

RESULTS:

Model-based simulations of MDA control in typical low-risk and higher-risk communities indicated that infection prevalence can be substantially reduced within 10 years only when there is a high degree of community participation (>70 %) with at least annual MDA. Significant risk for re-emergence of infection remains if MDA is suspended.

CONCLUSIONS:

In a stable (stationary) ecosystem, Schistosoma reproduction and transmission are sufficiently robust that the process of human infection continues, even under pressure from aggressive MDA. MDA alone is unlikely to interrupt transmission, and once mass treatment is suspended, the prevalence of human infection is likely to rebound to pre-control levels over a period of 25-30 years. MDA success in achieving very low levels of infection prevalence is highly dependent on treatment coverage and frequency within the local human population, and requires that both adults and children be included in drug delivery coverage. Ultimately, supplemental snail control and significant improvements in sanitation will be required to achieve full control of schistosomiasis by elimination of ongoing Schistosoma transmission.

PMID:
26489408
PMCID:
PMC4618728
DOI:
10.1186/s13071-015-1144-3
[Indexed for MEDLINE]
Free PMC Article
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