Evaluating survey designs for targeting preventive chemotherapy against Schistosoma haematobium and Schistosoma mansoni across sub-Saharan Africa: a geostatistical analysis and modelling study

Abstract Background Schistosomiasis control programmes primarily use school-based surveys to identify areas for mass drug administration of preventive chemotherapy. However, as the spatial distribution of schistosomiasis can be highly focal, transmission may not be detected by surveys implemented at districts or larger spatial units. Improved mapping strategies are required to accurately and cost-effectively target preventive chemotherapy to remaining foci across all possible spatial distributions of schistosomiasis. Methods Here, we use geostatistical models to quantify the spatial heterogeneity of Schistosoma haematobium and S. mansoni across sub-Saharan Africa using the most comprehensive dataset available on school-based surveys. Applying this information to parameterise simulations, we assess the accuracy and cost of targeting alternative implementation unit sizes across the range of plausible schistosomiasis distributions. We evaluate the consequences of decisions based on survey designs implemented at district and subdistrict levels sampling different numbers of schools. Cost data were obtained from field surveys conducted across multiple countries and years, with cost effectiveness evaluated as the cost per correctly identified school. Results Models identified marked differences in prevalence and spatial distributions between countries and species; however, results suggest implementing surveys at subdistrict level increase the accuracy of treatment classifications across most scenarios. While sampling intensively at the subdistrict level resulted in the highest classification accuracy, this sampling strategy resulted in the highest costs. Alternatively, sampling the same numbers of schools currently recommended at the district level but stratifying by subdistrict increased cost effectiveness. Conclusions This study provides a new tool to evaluate schistosomiasis survey designs across a range of transmission settings. Results highlight the importance of considering spatial structure when designing sampling strategies, illustrating that a substantial proportion of children may be undertreated even when an implementation unit is correctly classified. Control programmes need to weigh the increased accuracy of more detailed mapping strategies against the survey costs and treatment priorities.

Download Full-text

Evaluating survey designs for targeting preventive chemotherapy against Schistosoma haematobium and Schistosoma mansoni across Sub-Saharan Africa: a geostatistical analysis and modelling study

10.21203/rs.3.rs-36950/v3 ◽

2020 ◽

Author(s):

Kimberly Fornace ◽

Claudio Fronterrè ◽

Fiona M Fleming ◽

Hope Simpson ◽

Honorat Zoure ◽

...

Keyword(s):

Cost Effectiveness ◽

Schistosoma Haematobium ◽

Sampling Strategy ◽

Sub Saharan Africa ◽

Spatial Distributions ◽

Preventive Chemotherapy ◽

School Based ◽

Control Programmes ◽

Sub Saharan ◽

Survey Designs

Abstract Background: Schistosomiasis control programmes primarily use school-based surveys to identify areas for mass drug administration of preventive chemotherapy. However, as the spatial distribution of schistosomiasis can be highly focal, transmission may not be detected by surveys implemented at districts or larger spatial units. Improved mapping strategies are required to accurately and cost-effectively target preventive chemotherapy to remaining foci across all possible spatial distributions of schistosomiasis. Methods: Here, we use geostatistical models to quantify the spatial heterogeneity of Schistosoma haematobium and S. mansoni across sub-Saharan Africa using the most comprehensive dataset available on school-based surveys. Applying this information to parameterise simulations, we assess the accuracy and cost of targeting alternative implementation unit sizes across the range of plausible schistosomiasis distributions. We evaluate the consequences of decisions based on survey designs implemented at district and subdistrict levels sampling different numbers of schools. Cost data were obtained from field surveys conducted across multiple countries and years, with cost effectiveness evaluated as the cost per correctly identified school. Results: Models identified marked differences in prevalence and spatial distributions between countries and species; however, results suggest implementing surveys at subdistrict level increase the accuracy of treatment classifications across most scenarios. While sampling intensively at the subdistrict level resulted in the highest classification accuracy, this sampling strategy resulted in the highest costs. Alternatively, sampling the same numbers of schools currently recommended at the district level but stratifying by subdistrict increased cost effectiveness.Conclusions: This study provides a new tool to evaluate schistosomiasis survey designs across a range of transmission settings. Results highlight the importance of considering spatial structure when designing sampling strategies, illustrating that a substantial proportion of children may be undertreated even when an implementation unit is correctly classified. Control programmes need to weigh the increased accuracy of more detailed mapping strategies against the survey costs and treatment priorities.

Download Full-text

Evaluating survey designs for targeting preventive chemotherapy against Schistosoma haematobium and Schistosoma mansoni across Sub-Saharan Africa: a geostatistical analysis and modelling study

10.21203/rs.3.rs-36950/v2 ◽

2020 ◽

Author(s):

Kimberly Fornace ◽

Claudio Fronterrè ◽

Fiona M Fleming ◽

Hope Simpson ◽

Honorat Zoure ◽

...

Keyword(s):

Cost Effectiveness ◽

Schistosoma Haematobium ◽

Sampling Strategy ◽

Sub Saharan Africa ◽

Spatial Distributions ◽

Preventive Chemotherapy ◽

School Based ◽

Control Programmes ◽

Sub Saharan ◽

Survey Designs

Abstract Background: Schistosomiasis control programmes primarily use school-based surveys to identify areas for mass drug administration of preventive chemotherapy. However, as the spatial distribution of schistosomiasis can be highly focal, transmission may not be detected by surveys implemented at districts or larger spatial units. Improved mapping strategies are required to accurately and cost effectively target preventive chemotherapy to remaining foci across all possible spatial distributions of schistosomiasis. Methods: Here, we use geostatistical models to quantify the spatial heterogeneity of Schistosoma haematobium and S. mansoni across Sub-Saharan Africa using the most comprehensive dataset available on school-based surveys. Applying this information to parameterise simulations, we assess the accuracy and cost of targeting alternative implementation unit sizes across the range of plausible schistosomiasis distributions. We evaluate the consequences of decisions based on survey designs implemented at district and subdistrict levels sampling different numbers of schools. Cost data was obtained from field surveys conducted across multiple countries and years, with cost effectiveness evaluated as the cost per correctly identified school. Results: Models identified marked differences in prevalence and spatial distributions between countries and species; however, results suggest implementing surveys at subdistrict level increase the accuracy of treatment classifications across most scenarios. While intensively at subdistrict level resulted in the highest classification accuracy, this sampling strategy resulted in the highest costs. Alternatively, sampling the same numbers of schools currently recommended at district levels but stratifying by subdistrict increased cost effectiveness.Conclusions: This provides a new tool to evaluate schistosomiasis survey designs across a range of transmission settings. Results highlight the importance of considering spatial structure when designing sampling strategies, illustrating that a substantial proportion of children may be undertreated even when an implementation unit is correctly classified. Control programmes need to weigh the increased accuracy of more detailed mapping strategies against the survey costs and treatment priorities.

Download Full-text

Evaluating survey designs for targeting preventive chemotherapy against Schistosoma haematobium and Schistosoma mansoni across Sub-Saharan Africa: a geostatistical analysis and modelling study

10.21203/rs.3.rs-36950/v1 ◽

2020 ◽

Author(s):

Kimberly Fornace ◽

Claudio Fronterrè ◽

Fiona M Fleming ◽

Hope Simpson ◽

Honorat Zoure ◽

...

Keyword(s):

Cost Effectiveness ◽

Schistosoma Haematobium ◽

Sampling Strategy ◽

Sub Saharan Africa ◽

Spatial Distributions ◽

Preventive Chemotherapy ◽

School Based ◽

Control Programmes ◽

Sub Saharan ◽

Survey Designs

Abstract Background Schistosomiasis control programmes primarily use school-based surveys to identify areas for mass drug administration of preventive chemotherapy. However, as the spatial distribution of schistosomiasis can be highly focal, transmission may not be detected by surveys implemented at districts or larger spatial units. Improved mapping strategies are required to accurately and cost effectively target preventive chemotherapy to remaining foci across all possible spatial distributions of schistosomiasis. Methods Here, we use geostatistical models to quantify the spatial heterogeneity of Schistosoma haematobium and S. mansoni across Sub-Saharan Africa using the most comprehensive dataset available on school-based surveys. Applying this information to parameterise simulations, we assess the accuracy and cost of targeting alternative implementation unit sizes across the range of plausible schistosomiasis distributions. We evaluate the consequences of decisions based on survey designs implemented at district and subdistrict levels sampling different numbers of schools. Cost data was obtained from field surveys conducted across multiple countries and years, with cost effectiveness evaluated as the cost per correctly identified school. Results Models identified marked differences in prevalence and spatial distributions between countries and species; however, results suggest implementing surveys at subdistrict level increase the accuracy of treatment classifications across most scenarios. While intensively at subdistrict level resulted in the highest classification accuracy, this sampling strategy resulted in the highest costs. Alternatively, sampling the same numbers of schools currently recommended at district levels but stratifying by subdistrict increased cost effectiveness. Conclusions This provides a new tool to evaluate schistosomiasis survey designs across a range of transmission settings. Results highlight the importance of considering spatial structure when designing sampling strategies, illustrating that a substantial proportion of children may be undertreated even when an implementation unit is correctly classified. Control programmes need to weigh the increased accuracy of more detailed mapping strategies against the survey costs and treatment priorities.

Download Full-text

The Schistosomiasis Control Initiative (SCI): rationale, development and implementation from 2002–2008

Parasitology ◽

10.1017/s0031182009990400 ◽

2009 ◽

Vol 136 (13) ◽

pp. 1719-1730 ◽

Cited By ~ 208

Author(s):

A. FENWICK ◽

J. P. WEBSTER ◽

E. BOSQUE-OLIVA ◽

L. BLAIR ◽

F. M. FLEMING ◽

...

Keyword(s):

Neglected Tropical Diseases ◽

Integrated Control ◽

Monitoring And Evaluation ◽

Sub Saharan Africa ◽

Preventive Chemotherapy ◽

Schistosomiasis Control ◽

Control Programmes ◽

Sub Saharan ◽

Management Approaches ◽

Control Initiative

SUMMARYSchistosomiasis remains one of the most prevalent parasitic diseases in developing countries. After malaria, schistosomiasis is the most important tropical disease in terms of human morbidity with significant economic and public health consequences. Although schistosomiasis has recently attracted increased focus and funding for control, it has been estimated that less than 20% of the funding needed to control the disease in Africa is currently available. In this article the following issues are discussed: the rationale, development and objectives of the Schistosomiasis Control Initiative (SCI)-supported programmes; the management approaches followed to achieve implementation by each country; mapping, monitoring and evaluation activities with quantifiable impact of control programmes; monitoring for any potential drug resistance; and finally exit strategies within each country. The results have demonstrated that morbidity due to schistosomiasis has been reduced by the control programmes. While challenges remain, the case for the control of schistosomiasis has been strengthened by research by SCI teams and the principle that a national programme using ‘preventive chemotherapy’ can be successfully implemented in sub-Saharan Africa, whenever the resources are available. SCI and partners are now actively striving to raise further funds to expand the coverage of integrated control of neglected tropical diseases (NTDs) in sub-Saharan Africa.

Download Full-text

Cost effectiveness of single-dose nevirapine regimen for mothers and babies to decrease vertical HIV-1 transmission in sub-Saharan Africa

The Lancet ◽

10.1016/s0140-6736(99)07420-6 ◽

1999 ◽

Vol 354 (9185) ◽

pp. 803-809 ◽

Cited By ~ 43

Author(s):

E Marseille

Keyword(s):

Single Dose ◽

Cost Effectiveness ◽

Sub Saharan Africa ◽

Single Dose Nevirapine ◽

Sub Saharan ◽

Hiv 1

Download Full-text

The impact and cost‐effectiveness of community‐basedHIVself‐testing in sub‐Saharan Africa: a health economic and modelling analysis

Journal of the International AIDS Society ◽

10.1002/jia2.25243 ◽

2019 ◽

Vol 22 (S1) ◽

pp. e25243 ◽

Cited By ~ 13

Author(s):

Valentina Cambiano ◽

Cheryl C Johnson ◽

Karin Hatzold ◽

Fern Terris‐Prestholt ◽

Hendy Maheswaran ◽

...

Keyword(s):

Health Economic ◽

Cost Effectiveness ◽

Sub Saharan Africa ◽

Modelling Analysis ◽

Sub Saharan ◽

The Impact

Download Full-text

Competing interests, clashing ideas and institutionalizing influence: insights into the political economy of malaria control from seven African countries

Health Policy and Planning ◽

10.1093/heapol/czaa166 ◽

2020 ◽

Author(s):

Justin Parkhurst ◽

Ludovica Ghilardi ◽

Jayne Webster ◽

Robert W Snow ◽

Caroline A Lynch

Keyword(s):

Decision Making ◽

Malaria Control ◽

Qualitative Interviews ◽

Sub Saharan Africa ◽

African Countries ◽

Health Community ◽

Control Programmes ◽

Control Decision ◽

Sub Saharan ◽

Economic Considerations

Abstract This article explores how malaria control in sub-Saharan Africa is shaped in important ways by political and economic considerations within the contexts of aid-recipient nations and the global health community. Malaria control is often assumed to be a technically driven exercise: the remit of public health experts and epidemiologists who utilize available data to select the most effective package of activities given available resources. Yet research conducted with national and international stakeholders shows how the realities of malaria control decision-making are often more nuanced. Hegemonic ideas and interests of global actors, as well as the national and global institutional arrangements through which malaria control is funded and implemented, can all influence how national actors respond to malaria. Results from qualitative interviews in seven malaria-endemic countries indicate that malaria decision-making is constrained or directed by multiple competing objectives, including a need to balance overarching global goals with local realities, as well as a need for National Malaria Control Programmes to manage and coordinate a range of non-state stakeholders who may divide up regions and tasks within countries. Finally, beyond the influence that political and economic concerns have over programmatic decisions and action, our analysis further finds that malaria control efforts have institutionalized systems, structures and processes that may have implications for local capacity development.

Download Full-text

Addressing Pediatric HIV Pretreatment Drug Resistance and Virologic Failure in Sub-Saharan Africa: A Cost-Effectiveness Analysis of Diagnostic-Based Strategies in Children ≥3 Years Old

Diagnostics ◽

10.3390/diagnostics11030567 ◽

2021 ◽

Vol 11 (3) ◽

pp. 567

Author(s):

Mutita Siriruchatanon ◽

Shan Liu ◽

James G. Carlucci ◽

Eva A. Enns ◽

Horacio A. Duarte

Keyword(s):

Drug Resistance ◽

Cost Effectiveness ◽

Virologic Failure ◽

Pediatric Hiv ◽

Sub Saharan Africa ◽

Financial Investment ◽

Switching Strategy ◽

Wide Range ◽

Sub Saharan ◽

Living With Hiv

Improvement of antiretroviral therapy (ART) regimen switching practices and implementation of pretreatment drug resistance (PDR) testing are two potential approaches to improve health outcomes for children living with HIV. We developed a microsimulation model of disease progression and treatment focused on children with perinatally acquired HIV in sub-Saharan Africa who initiate ART at 3 years of age. We evaluated the cost-effectiveness of diagnostic-based strategies (improved switching and PDR testing), over a 10-year time horizon, in settings without and with pediatric dolutegravir (DTG) availability as first-line ART. The improved switching strategy increases the probability of switching to second-line ART when virologic failure is diagnosed through viral load testing. The PDR testing strategy involves a one-time PDR test prior to ART initiation to guide choice of initial regimen. When DTG is not available, PDR testing is dominated by the improved switching strategy, which has an incremental cost-effectiveness ratio (ICER) of USD 579/life-year gained (LY), relative to the status quo. If DTG is available, improved switching has a similar ICER (USD 591/LY) relative to the DTGstatus quo. Even when substantial financial investment is needed to achieve improved regimen switching practices, the improved switching strategy still has the potential to be cost-effective in a wide range of sub-Saharan African countries. Our analysis highlights the importance of strengthening existing laboratory monitoring systems to improve the health of children living with HIV.

Download Full-text

Are low and middle-income countries prioritising high-value healthcare interventions?

BMJ Global Health ◽

10.1136/bmjgh-2019-001850 ◽

2020 ◽

Vol 5 (2) ◽

pp. e001850

Author(s):

Ashley A Leech ◽

David D Kim ◽

Joshua T Cohen ◽

Peter J Neumann

Keyword(s):

Cost Effectiveness ◽

Cost Saving ◽

National Health ◽

Sub Saharan Africa ◽

Health Plans ◽

Middle Income ◽

Middle Income Countries ◽

Health Priority ◽

Sub Saharan ◽

Low And Middle Income

IntroductionSince resources are finite, investing in services that produce the highest health gain ‘return on investment’ is critical. We assessed the extent to which low and middle-income countries (LMIC) have included cost-saving interventions in their national strategic health plans.MethodsWe used the Tufts Medical Center Global Health Cost-Effectiveness Analysis Registry, an open-source database of English-language cost-per-disability-adjusted life year (DALY) studies, to identify analyses published in the last 10 years (2008–2017) of cost-saving health interventions in LMICs. To assess whether countries prioritised cost-saving interventions within their latest national health strategic plans, we identified 10 countries, all in sub-Saharan Africa, with the highest measures on the global burden of disease scale and reviewed their national health priority plans.ResultsWe identified 392 studies (63%) targeting LMICs that reported 3315 cost-per-DALY ratios, of which 207 ratios (6%) represented interventions reported to be cost saving. Over half (53%) of these targeted sub-Saharan Africa. For the 10 countries we investigated in sub-Saharan Africa, 58% (79/137) of cost-saving interventions correspond with priorities identified in country plans. Alignment ranged from 95% (21/22 prioritised cost-saving ratios) in South Africa to 17% (2/12 prioritised cost-saving ratios) in Cameroon. Human papillomavirus vaccination was a noted priority in 70% (7/10) of national health prioritisation plans, while 40% (4/10) of countries explicitly included prenatal serological screening for syphilis. HIV prevention and treatment were stated priorities in most country health plans, whereas 40% (2/5) of countries principally outlined efforts for lymphatic filariasis. From our sample of 45 unique interventions, 36% of interventions (16/45) included costs associated directly with the implementation of the intervention.ConclusionOur findings indicate substantial variation across country and disease area in incorporating economic evidence into national health priority plans in a sample of sub-Saharan African countries. To make health economic data more salient, the authors of cost-effectiveness analyses must do more to reflect implementation costs and other factors that could limit healthcare delivery.

Download Full-text