The role of improved housing in the African malaria recession

Lead Research Organisation: University of Oxford
Department Name: Zoology

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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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

 
Description Despite significant reductions in malaria globally since 2000, achieved via mass roll out of protective interventions such as bednets, malaria remains a major public health concern particularly in sub-Saharan Africa (SSA). This Fellowship aims to help address the urgent need to identify strategies to strengthen malaria control, with a focus on housing and the built environment. 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. To date, this Fellowship has provided insight on several key questions, with further research ongoing:
1. How are housing improvements associated with malaria across SSA? This question is important for understanding the potential impact of housing improvements on malaria, and was addressed through several multi-country analyses of national survey data. By analysing data for over 140,000 children across SSA, it was found that children living in improved housing had a 9% to 14% reduction in the odds of malaria infection, compared to those living in traditional housing; an association similar to that observed with the core intervention, insecticide treated bednets. A major update to this analysis to include over 800,000 children found that improved housing was associated with reductions not only in malaria, but diarrhoea, undernutrition and anaemia - highlighting the importance of housing for all aspects of child health.
2. How is housing changing across sub-Saharan Africa? This question is important since understanding changes in the built environment across the continent is the first step to leveraging these changes for improved malaria (and other vector-borne disease) control. Using a state-of-the-art geostatistical model, we published in Nature maps quantifying changes in housing across sub-Saharan Africa between 2000 and 2015. We found that the prevalence of 'improved housing' doubled from 11% to 23% in this period, but 50% of urban Africans still lived in slum conditions in 2015. The findings are relevant not only to public health but also to wider development goals, since housing is a basic human right and a core objective of Sustainable Development Goal 11.
3. What are the mechanisms by which good housing is protective against malaria, and how can these changes be scaled up? In addition to the two questions above, this Fellowship has enabled collaboration on research to understand in a specific setting how housing is changing and how these changes relate to malaria control in Uganda and how specific features of the house may affect mosquito survival in The Gambia, leading to new recommendations on the specific features of housing that can offer protection against malaria and other vector-borne disease.
Exploitation Route The outcomes of this funding include the first measurement of how housing is changing across sub-Saharan Africa, with major relevance not only to malaria control but also public health and development more generally. Housing is a basic human right and Sustainable Development Goal 11 aims to ensure universal, adequate housing by 2030. Achieving that goal is impossible without the means to measure progress. Additionally, the fellowship has generated the most comprehensive data to date quantifying the relationship between housing and malaria, as well as other health outcomes known to increase mortality - diarrhoea, undernutrition and anaemia. Such findings are critical to catalyse future research into 'healthy' house design and strategies for improving housing globally for better health.
Sectors Environment,Healthcare

URL https://pubmed.ncbi.nlm.nih.gov/30918405/
 
Description While this field of research is still developing, the findings of this Fellowship have contributed to a shift in thinking and recognition of the importance of housing and the built environment in malaria and vector-borne disease control. This is increasingly critical in the context of population growth and urbanisation in Africa and Asia. Among other fora, research findings have shaped discussions within the Roll Back Malaria Partnership's Vector Control Working Group https://endmalaria.org/our-work-working-groups/vector-control, the WHO Strategic Advisory Group on malaria eradication and the BOVA Network https://www.bovanetwork.org/, as well as stimulating interest in the role of housing improvements in humanitarian emergencies through the Global Shelter Cluster. The findings have also informed the following WHO documents and policies: Global Vector Control Response (2017); Guidelines for Malaria Control (2021); Global framework for the response to malaria in urban areas (2022).
Sector Environment,Healthcare
Impact Types Societal

 
Description Influencing policy guidelines (WHO Global Vector Control Reponse)
Geographic Reach Multiple continents/international 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
Impact The WHO Global Vector Control Response is the global plan for improving disease vector control 2017-2030. It will be presented to the World Health Assembly in May 2017 for approval. Within the GVCR, improving housing is strongly advocated as an inter-sectoral approach to VBD control. This is a landmark document since previously housing has not been considered important for malaria control policy.
URL http://www.who.int/malaria/global-vector-control-response/en/
 
Description Influencing policy guidelines (WHO guidance on housing and health)
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a advisory committee
 
Description Influencing policy guidelines (WHO guidance on malaria vector control)
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a advisory committee
 
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 New Urban Agenda
Geographic Reach Multiple continents/international 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
Impact Habitat III was a UN Conference on Housing and Sustainable Urban Development held in October 2016 in Quito, Ecuador. The meeting concluded with the adoption or the New Urban Agenda, which links with Sustainable Development Goal 11 to set global standards in sustainable urban development. Due to awareness and evidence generated through the work of myself and others on housing and malaria, vector-borne disease was included for the first time in the New Urban Agenda.
URL http://www.un.org/sustainabledevelopment/blog/2016/10/newurbanagenda/
 
Description WHO Global framework for the response to malaria in urban areas
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a national consultation
 
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
 
Description Risk Assessment of Mosquito-borne Diseases in Dar es Salaam, Tanzania Based on Deep Learning and Remote Sensing
Amount 19,861,517 kr. (DKK)
Funding ID 0069116 
Organisation Novo Nordisk Foundation 
Sector Charity/Non Profit
Country Denmark
Start 01/2022 
End 12/2026
 
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 BOVA Meeting presentation 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact I presented my fellowship research at the BOVA Network annual meeting in London, March 2018.
Year(s) Of Engagement Activity 2018
 
Description Co-chairing of working group meeting 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Co-chaired a 3 hour meeting at the Roll Back Malaria Vector Control Working group. Representation from academia, ministries of health, policymakers, industry. Discussed policy recommendations relevant to housing and malaria.
Year(s) Of Engagement Activity 2019
 
Description Global health conference (ASTMH, Atlanta, USA, November 20016) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact I presented the findings of the first objective of my fellowship, a multi-country analysis of housing and malaria risk in African children, as a poster.
Year(s) Of Engagement Activity 2016
URL https://www.astmh.org/ASTMH/media/Documents/ASTMH-2016-Annual-Meeting-Abstract-Book.pdf
 
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 Housing and Malaria Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact I organised a workshop at the London School of Hygiene & Tropical Medicine on housing and health.
Year(s) Of Engagement Activity 2019
 
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 Online/social media presence 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I have maintained a strong online presence through Google Scholar, Twitter and my institutional webpages, to raise awareness of the MRC funding for my research and to promote issues and outputs of broad public interest.
Year(s) Of Engagement Activity 2016,2017
URL https://twitter.com/lucytusting
 
Description Paper dissemination 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Social media and institutional coverage of a paper from my fellowship on housing and malaria.

http://www.ox.ac.uk/news/2017-02-22-modern-housing-may-cut-malaria-risk-sub-saharan-africa
http://researchnews.plos.org/2017/02/21/fly-on-the-wall-modern-housing-and-malaria/
https://www.lshtm.ac.uk/newsevents/news/2017/modern_housing_malaria_risk.html
http://www.map.ox.ac.uk/modernhousing/
Year(s) Of Engagement Activity 2017
URL http://www.ox.ac.uk/news/2017-02-22-modern-housing-may-cut-malaria-risk-sub-saharan-africa
 
Description Policy meeting (Roll Back Malaria, Geneva) 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Presentation of research from fellowship on housing and malaria to an international audience of 250 people, which sparked numerous questions and interest in the potential of improved housing to reduce malaria within National Malaria Control Programmes. Attendance by members of national governments, UN-Habitat and WHO.
Year(s) Of Engagement Activity 2017
URL http://www.rollbackmalaria.org/architecture/working-groups/vcwg
 
Description Presentation to Oxford University Tropical Epidemiology Group 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact 30 people attended this seminar, which increased interest in housing and vector-borne disease.
Year(s) Of Engagement Activity 2017
 
Description Presentation to Roll Back Malaria 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact Talk to 250 people presenting the Nature paper just accepted that is one of the main outputs of my fellowship.
Year(s) Of Engagement Activity 2019
 
Description Press release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Press release for new publication on malaria and housing, released through the journal (PLOS Medicine) and University of Oxford.
Year(s) Of Engagement Activity 2017
URL http://researchnews.plos.org/2017/02/21/fly-on-the-wall-modern-housing-and-malaria/
 
Description Radio interview (Voice of America) 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I gave a radio interview with Steve Baragona, Voice of America on 17th February 2017, regarding recently published research on malaria and housing (from my fellowship).

NB interview URL is not yet live.
Year(s) Of Engagement Activity 2017
 
Description University seminar (Durham) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact I gave a presentation on my research and my career to date to a group of 40 Biology undergraduate students at Durham University. There was a drinks reception afterwards during which I was asked many questions about doing a Masters and routes into academic research. The department reported increased interest in further study amongst these students.
Year(s) Of Engagement Activity 2017
URL http://community.dur.ac.uk/philip.stephens/SBBSSeminars.htm
 
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