The role of improved housing in the African malaria recession

Lead Research Organisation: London Sch of Hygiene and Trop Medicine
Department Name: Infectious and Tropical Diseases

Abstract

Malaria is a mosquito-borne disease, mainly confined to the tropics. Today, malaria control is at a pivotal juncture. The disease remains a major source of human illness and death, killing around 600,000 people annually. Yet the past fifteen years have seen great advances in controlling malaria, with a third reduction in the annual incidence of cases. These reductions have been mainly achieved by distributing chemically-treated bed nets for people to sleep beneath and by spraying houses with chemicals that kill mosquitoes. However, mosquitoes have become resistant to the chemicals used, meaning that additional tools are urgently needed to avoid losing the progress made.

Since malaria is a 'disease of poverty', strongly influenced by its environment, there is heightened interest in using broader, non-chemical approaches for its control, by working with sectors outside health such as agriculture, water and sanitation and urban planning. This is especially pertinent as we approach the launch of the Sustainable Development Goals for international development later in 2015. The research proposed here will specifically investigate how one such approach - improving housing - can help to reduce malaria in sub-Saharan Africa.

Good housing, traditionally a key pillar of public health, remains underexploited in malaria control. Yet most bites by malaria mosquitoes in sub-Saharan Africa are received indoors at night, so the home can be a risky place. Historically, improved living conditions and house screening contributed to malaria elimination in Europe and the USA. Today, studies have shown that well-built housing can help to protect against malaria in many African settings. However, house design has been largely neglected as a potential malaria control tool, due to reliance on other interventions.

Today, unprecedented population expansion and socioeconomic development in sub-Saharan Africa presents an unrivalled opportunity to build healthy homes. The continent's population is projected to double between 2010 and 2040 to nearly two billion and may surpass three billion by 2070, with 144 million new houses needed by 2030 in rural areas alone. Housing quality is also transforming across much of the continent, as incomes increase. This economic and cultural revolution represents an exceptional opportunity for malaria control.

The aim of this fellowship is to investigate the potential contribution of better housing to malaria control in Africa. This will be achieved by addressing three questions:
i) How is malaria associated with housing quality in different parts of sub-Saharan Africa?
ii) To what extent has housing improved in Africa, and how does this change relate to trends in malaria endemicity, 2000-2015?
iii) What is the potential impact of using better housing as an intervention against malaria?

To answer these questions, state-of-the-art modelling approaches will be used (1) to assess the association between house design and malaria in multiple African countries, (2) to quantify how housing improved in Africa between 2000 and 2015, (3) to understand how trends in malaria between 2000 and 2015 were related to changes in housing and (4) to estimate the total number of malaria cases in Africa that may be averted by ongoing housing improvements. This study will exploit the world's largest collection of malaria surveys, the Malaria Atlas Project, together with nearly 200 demographic and health surveys from over 40 countries in sub-Saharan Africa.

In summary, this study will evaluate the potential of building better homes to impact on malaria in Africa. The outcomes of this research will provide critical information to guide research and policy decisions relating to sustainable malaria control, at a pivotal time.

Technical Summary

BACKGROUND: Since most malaria transmission occurs indoors in sub-Saharan Africa (SSA), housing quality is an important determinant of malaria risk, through its effect on house entry by mosquitoes. Unprecedented population expansion and rapid socioeconomic development in SSA presents an unrivalled opportunity to advance malaria control and elimination by building healthy homes.

AIM: To investigate the role of improved housing in the African malaria recession.

METHODS: Two principal data sources will be used: (i) the Demographic and Health Survey (DHS), Malaria Indicator Survey (MIS) and Multiple Indicator Cluster Survey (MICS) programs and (ii) the Repository of Open Access Data of the Malaria Atlas Project (ROAD-MAP II). First, the association between house quality and prevalence of malaria in children will be examined (a) in Upper River Region, The Gambia, using a 2010 parasitological survey of c3800 children and remotely-sensed imagery to classify house type and (b) in 22 countries in SSA, by applying multilevel modelling to MIS and DHS surveys. Second, changes in housing quality at the district level across SSA, 2000-2015, will be estimated by fitting housing data from georeferenced DHS/MIS/MICS surveys within a multilevel model using a Bayesian framework. Third, the relationship between housing improvements and changes in malaria endemicity in SSA, 2000-2015, will be modelled at three spatial scales using data from Objective 2 and ROAD-MAP-II. Fourth, the total number of malaria cases averted in SSA in 2015 due to housing improvements during 2000-2015 will be estimated using a spatiotemporal model and counterfactual framework.

SUMMARY: The application of geospatial modelling to large existing datasets will generate novel evidence on the relationship between housing and malaria and the impact of housing improvements on malaria endemicity, yielding critical and timely policy recommendations for sustainable malaria control.

Planned Impact

The proposed research will examine the potential for better housing to control malaria, helping to address the urgent need for vector control tools beyond long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Immediate beneficiaries will be academics, policy-makers, malaria control programmes and non-governmental organisations. The ultimate beneficiaries will be the two billion people living at risk of malaria worldwide.

Academics within public health will benefit through the generation of new data on changes in housing quality in Africa, the assembly of new evidence on housing and malaria and the application of tailored statistical approaches to large survey datasets and Malaria Atlas Project data (see Academic Beneficiaries). The research will be of particular benefit to epidemiologists conducting field studies of housing as a malaria intervention, by generating macro-level data to (a) gauge the potential impact of housing in different settings and (b) guide the design of future field studies. Other beneficiaries will include public health entomologists seeking supplementary tools for malaria vector control; malaria elimination specialists seeking long-term, sustainable interventions; malariologists interested in understanding of the causes of the African malaria recession; and spatial epidemiologists and health geographers studying the effects of the environment on health. The use of large demographic and health survey datasets will benefit methodologists who work with similar data to study risk factors for health outcomes. Exploitation of the Malaria Atlas Project will make constructive use of this valuable resource. The research will exploit the UK Medical Research Council's strategic investments in health research in The Gambia (see letter). Academic beneficiaries outside the health sphere will include remote-sensing experts and urban geographers, who will benefit from the application of remotely-sensed data and the analysis of housing variables within large survey datasets; architects working on housing and health; and cross-disciplinary research teams from social science, public health and development economics, specialising the relationship between development and health.

Policy-makers and national malaria control programmes (NMCPs) will benefit in three ways. First, given that LLINs and IRS are increasingly threatened by insecticide resistance, there is an urgent need to evaluate supplementary methods of vector control, such as housing. Second, the proposed research will generate new evidence on multisectoral malaria control, with which to guide programme design and to support advocacy. Third, if housing shows potential as a sustainable intervention, the long-term costs of malaria control and elimination may be reduced. Tangible, short-term benefits for policy-makers and NMCPs will be: (a) estimations of the potential impact of housing improvements, (b) identification of the malaria transmission settings where housing is likely to be more and less effective and (c) generation of data and maps for advocating for multisectoral (housing-health) malaria control. In turn, the development and housing sectors will benefit from important new data documenting changes in housing quality at the district level in Africa since 2000 and from data to promote advocacy for better housing (the 2013 UNDP Multisectoral Action framework for Malaria states that 'encouraging better housing is a social objective, not simply a malaria control action'). Should housing improvements be more systematically implemented as part of the broader development and health agenda, the ultimate beneficiaries will be the populations of malaria-endemic countries, whose quality of life will improve through better health and access to decent housing.

Publications

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Seelig F (2020) The COVID-19 pandemic should not derail global vector control efforts. in PLoS neglected tropical diseases

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Lindsay SW (2021) Recommendations for building out mosquito-transmitted diseases in sub-Saharan Africa: the DELIVER mnemonic. in Philosophical transactions of the Royal Society of London. Series B, Biological sciences

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Tusting LS (2021) Assessing the health benefits of development interventions. in BMJ global health

 
Description Multisectoral Working Group, Roll Back Malaria
Geographic Reach Multiple continents/international 
Policy Influence Type Membership of a guideline committee
Impact Membership of Multisectoral Working Group on malaria under the umbrella of WHO and the Roll Back Malaria Partnership, working to improve malaria control through intersectoral collaboration
 
Description WHO Guidelines Development Group on malaria vector control
Geographic Reach Multiple continents/international 
Policy Influence Type Membership of a guideline committee
Impact Membership of the WHO Guidelines Development Group on malaria vector control, including discussion of housing improvements for malaria control. This will update the global guidelines for malaria control, to be released in 2021.
URL https://apps.who.int/iris/bitstream/handle/10665/310862/9789241550499-eng.pdf
 
Title Demographic and Health Survey processing 
Description Collaboration on Github site providing code for downloading and handling DHS health data 
Type Of Material Data handling & control 
Year Produced 2020 
Provided To Others? Yes  
Impact This Github site provides code that has contributed to a number of publications, detailed here: https://github.com/harry-gibson/DHS-Data-Extractions/tree/main/Building_Quality_And_Child_Health 
URL https://github.com/harry-gibson/DHS-Data-Extractions/tree/main/Building_Quality_And_Child_Health
 
Title Housing in Africa 
Description Gridded data on prevalence of improved housing in sub-Saharan Africa in 2000 and 2015 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact These data have been used in other outputs, such as https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(20)30398-3/fulltext 
URL https://malariaatlas.org/research-project/housing_in_africa/
 
Description Building Out Vector Borne Diseases in Sub-Saharan Africa (BOVA) Network 
Organisation Durham University
Department School of Biological and Biomedical Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution I am co-director of the BOVA Network, funded by the UK Global Challenges Research Fund. I conceived of the idea and co-wrote the initial proposal. BOVA is an interdisciplinary network focusing on preventing vector-borne diseases through improving the built environment.
Collaborator Contribution My partners at Durham University manage the running of the network. The network directors are Prof Steve Lindsay (Durham University) and PRof Mike Davies (UCL).
Impact Annual Meeting in London, March 2018 in partnership with the Royal Society of Tropical Medicine and Hygiene. 8 pump-priming projects valuing £100k funded, to conduct basic research on housing and vector-borne disease in Africa.
Start Year 2018
 
Description Building Out Vector Borne Diseases in Sub-Saharan Africa (BOVA) Network 
Organisation University College London
Country United Kingdom 
Sector Academic/University 
PI Contribution I am co-director of the BOVA Network, funded by the UK Global Challenges Research Fund. I conceived of the idea and co-wrote the initial proposal. BOVA is an interdisciplinary network focusing on preventing vector-borne diseases through improving the built environment.
Collaborator Contribution My partners at Durham University manage the running of the network. The network directors are Prof Steve Lindsay (Durham University) and PRof Mike Davies (UCL).
Impact Annual Meeting in London, March 2018 in partnership with the Royal Society of Tropical Medicine and Hygiene. 8 pump-priming projects valuing £100k funded, to conduct basic research on housing and vector-borne disease in Africa.
Start Year 2018
 
Description Housing and health in humanitarian crises 
Organisation Catholic Relief Services
Country United States 
Sector Charity/Non Profit 
PI Contribution Joint application made for funding on health and housing in humanitarian crises in October 2020
Collaborator Contribution Contribution to application
Impact Joint application for funding, which was not successful but the team will re-apply next year. The collaboration is multi-disciplinary, cutting across the health and humanitarian crises sectors.
Start Year 2020
 
Description Housing and health in humanitarian crises 
Organisation Makerere University College of Health Sciences
Country Uganda 
Sector Academic/University 
PI Contribution Joint application made for funding on health and housing in humanitarian crises in October 2020
Collaborator Contribution Contribution to application
Impact Joint application for funding, which was not successful but the team will re-apply next year. The collaboration is multi-disciplinary, cutting across the health and humanitarian crises sectors.
Start Year 2020
 
Description Housing and health in humanitarian crises 
Organisation Oxford Brookes University
Country United Kingdom 
Sector Academic/University 
PI Contribution Joint application made for funding on health and housing in humanitarian crises in October 2020
Collaborator Contribution Contribution to application
Impact Joint application for funding, which was not successful but the team will re-apply next year. The collaboration is multi-disciplinary, cutting across the health and humanitarian crises sectors.
Start Year 2020
 
Description Roll Back Malaria Housing and Malaria Work Stream 
Organisation Roll Back Malaria
Country Switzerland 
Sector Charity/Non Profit 
PI Contribution The Vector-Borne Diseases and the Built Environment Work Stream of the Roll Back Malaria Partnership's Vector Control Working Group aims to bring together the housing and malaria communities and establish a network of interested parties from academia, national governments, WHO and other policy makers, to support basic and applied research and develop pathways to scale-up housing interventions against malaria and other vector-borne diseases through inter-sectoral collaboration. There are currently 75 members. I was a founding member of this Work Stream in 2014 and in November 2016 was made Co-Chair, providing leadership and convening the annual meeting in Geneva, the most recent of which was held in February 2017.
Collaborator Contribution Provide administrative and financial support for the hosting and maintenance of the Work Stream.
Impact Policy documents: Consensus Statement on Housing and Malaria, released by RBM, UNDP and UN-Habitat October 2015.http://www.rollbackmalaria.org/files/files/working-groups/VCWG/RBM%20VCWG%20Housing%20and%20Malaria%20Consensus%20Statement_final.pdf
Start Year 2016
 
Description Steering group, LSHTM Centre on Climate Change and Planetary Health 
Organisation London School of Hygiene and Tropical Medicine (LSHTM)
Country United Kingdom 
Sector Academic/University 
PI Contribution https://www.lshtm.ac.uk/research/centres/centre-climate-change-and-planetary-health Member of the Steering Group; this LSHTM Centre aims to fund and share research on climate and environmental health.
Collaborator Contribution Partners contribute research on climate change and planetary health
Impact Tusting LS, Bradley J, Bhatt S, Gibson HS, Weiss DJ, Shenton FC, Lindsay SW, 2020. Environmental temperature and growth faltering in African children: a cross-sectional study. Lancet Planetary Health, 4: e116-e123.
Start Year 2020
 
Description Sustainable development of global sand resources 
Organisation University of Colorado Boulder
Country United States 
Sector Academic/University 
PI Contribution Partnership on research on the sustainable development of global sand resources, including their use in housing
Collaborator Contribution Research contribution and data on housing in Africa, currently under peer review. Joint seminar at LSHTM.
Impact Multi-disciplinary; geographical sciences and health. Publication in progress.
Start Year 2020
 
Description Guest editorial 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Blog post for the Royal Society of Tropical Medicine and Hygiene on housing and malaria
Year(s) Of Engagement Activity 2020
URL https://rstmh.org/news-blog/blog/housing-and-health-can-we-build-vector-borne-disease-out-of-africa
 
Description Interview and newsletter 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Interview on housing and malaria research for MESA Track (Malaria Eradication Strategic Alliance)
Year(s) Of Engagement Activity 2020
URL http://mesamalaria.org/updates/housing-improvements-reduce-malaria-transmission-conversation-dr-lucy...
 
Description Invited presentation at international conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Invited presentation at the American Society for Tropical Medicine and Hygiene, in a symposium on urban malaria transmission in Africa
Year(s) Of Engagement Activity 2020
 
Description Workshop 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact Presentation to the Global Shelter Cluster's "Health and Shelter Learning Day", to educate and discuss the potential for housing improvements to affect health in humanitarian crises.
Year(s) Of Engagement Activity 2020