A research agenda for prevention of vector-borne diseases through the built environment

Building Out Vector Borne Diseases in sub-Saharan Africa (BOVA Network)

Introduction

Between 2000 and 2015 malaria infection prevalence in sub-Saharan Africa (SSA) halved and the incidence of clinical disease fell by 40%, due largely to vector control with long-lasting insecticidal nets and indoor residual spraying (WHO World Malaria Report 2018)1. However there has been no significant progress in reducing global malaria from 2015 - 2017 and the 10 highest burden countries in Africa reported increases in cases of malaria in 2017 compared with 2016.

The built environment is frequently the focal point where humans are bitten by vectors of disease. Improvements to houses and the peri-domestic environment can be used to “engineer” against vector-borne diseases (VBDs) (Wilson et al, 2019)2. There has been a marked transformation of housing in urban and rural sub-Saharan Africa between 2000 and 2015, with a doubling in the prevalence of improved housing (Tusting et al, 2019)3. However, 53 million urban Africans were still living in unimproved housing in 2015. The drive for better housing should be viewed as an opportunity to introduce vector control measures along with other improvements.

In 2015 Roll Back Malaria, the United Nation’s (UN) Development Programme and UN Habitat produced a consensus statement (see appendix) outlining the key research questions that need to be addressed to help reduce the threat of VBDs through the built environment. Since then research in this important area has expanded, and here we report the conclusions of a major workshop (Second BOVA Open Network Meeting, UN-Habitat, Nairobi 4-5 th April 2019) held to identify the most important areas for future research in five main topic areas.

1: Basic Research on vectors & the built environment

2: Strategic thinking/advocacy

3: New tools and approaches

4: Economics and Scale Up

5: Community –based approaches

The discussion in each of the areas was led by a couple of topic champions, the rapporteurs were BOVA network members who had been awarded sponsored places to attend the meeting.

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Sponsored places were available to network members who were invited to submit brief descriptions of their own research proposals. These were judged by the BOVA management team and places awarded to the top ten. Each group determined their own format for the discussion, they explored the current gaps/needs and came up with a shortlist of proposals for future research.

1: Basic research on vectors & the built environment

Topic Champions: Steve Lindsay & Rob McCann

Rapporteurs: Musa Jawara, Jeroen Spitzen

There is a need to better understand mosquito behaviour and how they are attracted into houses. Measurements of airflow and weather conditions can be used in simulation models to predict how carbon dioxide (a major mosquito attractant) leaks out of houses and thereby draws in mosquitoes. It is important to combine this with studies of human behaviour to gain a comprehensive understanding of how and when people are exposed to mosquito bites. There is some overlap with Topic 3, although 3 focusses more on the human element discussing house design, setting, cultural considerations and materials. This group also noted that there is an urgent need for a multi-centred survey of mosquito vectors across Africa. Alongside species which are the main malaria vectors, the survey should include Aedes aegypti being a predominantly urban mosquito responsible for transmitting diseases such as dengue, chikungunya, Zika and yellow fever. There is a disturbing lack of basic knowledge of this globally occurring species.

Proposals

Proposals for this topic area can be summarized and memorized as 4M’s

1. M easure airflow and basic weather conditions (temperature, relative humidity, atmospheric pressure) in- and around houses.

2. M odel airflow around different building structures. Building structure and materials affect the airflow and host cue emanations emitted from houses. These can be modelled based on the measurements under M1.

3. M osquito behaviour linkage. By filming mosquitoes or using movement sensors, mosquito approach and their behaviour near house entry- and exit points can be integrated with the airflow/odour model. The linked model can form the basis for adjusted house designs.

In addition, it will be important to monitor human behaviour in and around homes and incorporate this into airflow/ mosquito models. For example with the electrification of rural Africa there is an increase of homes with light emitting diode (LED) lights, encouraging people to stay outside their bednets for longer while indoors. It is not known how this would affect the approach of house entering and exiting mosquitoes.

4. M ake or Modify interventions. By modelling multiple peri-domestic environmental settings across Africa and integrating local entomological data, vector interventions can be customized in a cost effective manner. The initial design of houses should be based on the

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model outcomes, and existing houses can be modified in a number of ways such as adjusting key entry points, changing airflow or using suitably placed decoy traps.

2: Strategic thinking/advocacy

Topic Champions: Emily Nix & Sarah Ruel-Bergeron

Rapporteurs: Rachel Nguela, Julien Zahouli

A systematic review of housing as an intervention to control VBDs, should be undertaken. There was some overlap with Topics 1 and 3 in that there is a need to evaluate the components of health and housing and use the information to establish new tools/protocols to improve homes and the built environment. The importance of community engagement was also highlighted. Steps should be taken to facilitate better networking between BOVA members. More use should be made of BOVA Network members as advocates, especially to promote VBD control to practitioners in the built environment.

Proposals

1. Systematic review

A formal systematic review should be undertaken on the work that has been done relating housing and VBD. The review would broaden the knowledge on housing and health in general, capture the co-benefits for both, identify unintended consequences of changes to the built environment and information gaps. It would be important for the review findings to be widely disseminated as both a formal scientific paper and in a form accessible to wider communities.

2. Dialogue between Vector-borne diseases and Built environment

Vector-borne disease practitioners and those from the built environment should harmonise their terminology to set up a common language. This would facilitate efficient dialogue and collaboration on joint projects. To ensure equitable access, information should be disseminated using different media as appropriate. Cross-over between disciplines should see the concept of healthy housing taught from school age through to professional training of entomology/public health, architecture, and design students.

3. Development of a research toolkit

Studies should explore the interaction between the different components of health and housing. Proper testing and evaluation of interventions is essential. Toolkits are required for the following -

Identification of risks

Experimental design e.g. Randomised control trials, community participation

Experimental protocols

Assessment and evaluation of interventions

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There is already a comprehensive World Health Organisation guide available to help in this area -

How to design vector control efficacy trials. Guidance on phase III vector control field trial design 4

https://www.who.int/neglected_diseases/vector_ecology/resources/WHO_HTM_NTD_VEM_2017.03/en/

4. Community engagement (see also Topic area no. 5)

The group noted that community engagement is essential, and the means of communication needs to be tailored to the audience (policy-makers, decision-makers, manufacturers, health professionals, urban planners, students, communities, etc.). The community’s knowledge of health, housing and cost issues should be considered and their priorities taken into account. Building material durability, model, structure and design, may all influence community acceptance and adoption of a project.

5. Advocacy and the BOVA network

As for community engagement, advocacy should be adapted to the audience based on a practical and pragmatic approach. The research team and network members should also work with communities, health professionals, urban planners, private and public sectors, NGOs, and relevant ministries. They should seek to influence housing policies which take into account the need to protect people from VBDs. It should be explained how improvements to housing and the built environment will benefit health and wellbeing in general.

There is a need to attract other people to the Network in order to share knowledge, expertise, and experience. Network members should interact with students of architecture and engineering, and teach housing-health as a discipline. Members should be ambassadors for the aims of the BOVA Network.

use BOVA network members as ambassadors

present at conferences, symposia, and congresses

use diverse means of communication, develop simple infographics, key messages, videos, social media, media campaigns

make more use of the BOVA website and twitter

canvas members views on the website and how they might be better supported by the network

give BOVA network members more access to one another to facilitate collaboration and sharing of knowledge and experience

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3: New tools and approaches

Topic Champions: Fredros Okumu & Jakob Knudsen

Rapporteurs: Dingani Chinula, Robert Jones

House design and materials should be considered in the round with the cultural setting: what people desire of their homes, and how people use the space both inside and immediately outside their houses. Houses designed to limit risk from VBDs must also be comfortable, environmentally-friendly and sustainable. Capacity building is important to better utilise local builders, craftspeople and materials. There is a very thorough review in the pipeline which looks in detail at all aspects of house design suitable for SSA (Von Seidlein et al 2019, in press)5. Here are set out four outline research proposals for assessing different designs, including their acceptability and sustainability.

Proposals

Proposal 1: Open house (or other novel) designs for Africa

See if an open house design would work in Africa. It is important that both the indoor and outdoor (private and public spaces) are included

Behavioural aspect – to understand people’s behaviour better, their use of the peri-domestic space and what their needs are; encourage behaviour change where necessary, but also try to find solutions which are compatible with current practices

Build capacity of local construction teams

Evaluation of impact

Proposal 2: Simulation models to test different house designs and settings (see Topic 1)

Proposal 3: Research different building materials

Research different materials e.g. netting that is as strong as a wooden door, different roofing materials

Must be durable, low thermal mass, low carbon footprint, e.g. interlocking clay bricks use high pressure to compact them and therefore require little cement

Construction of prototypes is important to introduce and test new ideas and technologies

Proposal 4: Review of house improvements and their scalability

Create designs which can be made readily available, are in harmony with human needs and scalable.

Then test and evaluate

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4: Economics and Scale Up

Topic Champions: Adamu Addissie & Anne Wilson

Rapporteur: Hannah Wood

Here there was more detailed discussion of who will build/buy healthy houses. Different routes will be needed to provide for the poorest who require help from government or other microfinancing schemes, while wealthier people are already building new homes for themselves. Government could play a role in setting building standards with healthy homes as the objective. There was discussion of how to incorporate health with housing.

Proposals

Make use of existing loans to housing providers, but combined with:

o Capacity building in public sector

o Capacity building in private sector

o Policy and standards change at national level

o Healthy Home concept, could make loan conditional on building a Healthy Home

o Locally produced materials

Work in different sectors of housing production (both urban and rural):

o Self build (low income, or ultra low income) – informal

o Mass public housing – formal

o Mass private housing – formal

o Itinerant population rural and urban

Explore joint delivery between health-care providers, other public services, house builders. Very important to widen the dialogue, in Singapore their highly organised vector control programme is incorporated into environmental management.

Scale up

o Financing from major funders such as the Bill & Melinda Gates Foundation, International Financial Institutions (e.g. development banks), CitiesAlliance https://www.citiesalliance.org/.

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o Consider non-governmental funders. For example, although The Overseas Private Investment Corporation (OPIC) is a U.S. government agency, its role is to help American businesses invest in emerging markets.

o The Centre for Affordable Housing Finance in Africa (CAHF) http://housingfinanceafrica.org/ an independent think tank working to support and grow housing markets in Africa, publishes a Housing Finance in Africa Yearbook.

o Make use of novel approaches such as iBuild https://www.ibuild.global/ which is a mobile phone platform connecting those in need of shelter with construction people and housing support services

o Work with policymakers to determine “healthy home” regulations and guidelines for their implementation.

o Find ways to address the construction skills gap and build capacity. Work with organisations such as Tanzania’s Vocational Education and Training Authority (VETA) https://www.veta.go.tz/

5: Community –based approaches

Topic Champions Francis Mutuku & Amy Robyn Krystosik

Rapporteurs: Majo Carrasco Tenezaca, Ebrima Jatta, Ng’ang’a Murima

Community based research is a valid field in its own right, it should not be viewed as a mere accessory to other projects. Indeed in all the other research areas there was a call for sincere community engagement, improved understanding of people’s everyday behaviour and practices; and of their priorities. There was a strong plea to be led by communities themselves and to throw the net wide to include all stakeholders.

Proposals

Communities should be engaged in the planning stages from the very outset and throughout the life of the project. They are likely to have important knowledge and information to contribute and it will give them ownership of the research. They should be involved in the design, data/information collection, interpretation and dissemination of findings. They should also have the opportunity to raise their own questions e.g. in focus group discussions, and there should be space to respond to unexpected considerations as they arise during the course of the work.

Identifying the key actors is important. The community we are working with may not always be the group of people most directly affected by the problem. We may want to partner with other stakeholders such as those with special knowledge or influence in a community, government or local authorities. It is likely to be necessary to approach different groups,

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especially initially - to create awareness of the project and to understand the complexity of who may be involved and/ or affected by a problem.

Seek out positive deviants (Nieto-Sanchez et al, 2015)6 - "individuals whose uncommon practices and behaviours enable them to develop better solutions to problems than their neighbours who have access to the same resources" (Singhal, 2011)7

Take time to research and properly understand the complexities. Recognise that the disease itself may not be the primary problem or priority, for example people may be too poor to plaster their walls leaving cracks in which triatomine insects can shelter, the primary problem is poverty not Chagas disease.

Questions of equity are especially important for projects where the aim is to have a long term impact. Often those most directly affected by a problem are the ones with the least economic resources, but they can contribute in other ways (see above).

Build sustainability into projects. Find ways in which practices to control VBDs bring along additional benefits e.g. income generation (BOVA pump prime project Trash to Treasure). Financial benefit and/or increased prestige can motivate people to stay engaged with a project.

Common themes in all five topic areas

- Engage communities (all stakeholders) top priority- Need to link with the full gamut of those who build houses- Capacity build- Varied means of financing new homes and/or home improvements - Establish standardised tools/protocols for testing and evaluation

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Funding sources

Finally, an important question not directly addressed in the discussion of research priorities, is where to seek funding for this type of research. In the past interdisciplinary proposals have missed out on funding because they did not fit neatly into any one category. Fortunately there is an increasing recognition of the value of a multi-disciplinary approach and there are now calls specifically targeting cross-sectoral research. Aspects of housing-health could be captured under the umbrella of the “one-health” concept that aims to be broader in scope.

Since one of the primary objectives of the BOVA Network is to build pathways for scaling up, we recently hosted a “Big Money” workshop to explore opportunities for larger, more ambitious projects:

1. International Financial Institutions (e.g. African Development Bank)It may be possible to add technical assistance / advisory projects on to larger loans or investments. In some cases they might consider making a grant for a specific research or pilot project.

2. PhilanthropyThe philanthropy world is broad, as well as the big ones focussing on urban issues (Childrens Investment Fund / Bloomberg as funders of C40) there are probably many others that could be engaged in the VBD field.

3. Impact investmentThere is a growing movement of so-called ‘impact investing’, whereby the primary objective of the investor is not profit but ‘making a difference’ and improving lives.

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References

1. WHO World Malaria Report 2018 https://endmalaria.org/sites/default/files/World%20Malaria%20Report%202018.pdf

2. Wilson et al (2019). Revisiting an old idea: engineering against vector-borne diseasesin the domestic environment. Trans R Soc Trop Med Hyg, 113, 53–55.

3. Tusting et al (2019). Mapping changes in housing in sub-Saharan Africa from 2000 to 2015. Nature, 568 (7752), 391+https://www.nature.com/articles/s41586-019-1050-5

4. How to design vector control efficacy trials. Guidance on phase III vector control field trial design https://www.who.int/neglected_diseases/vector_ecology/resources/WHO_HTM_NTD_VEM_2017.03/en/

5. Von Seidlein et al (2019). Knowledge gaps in the construction of rural healthy homes: a research agenda for improved low-cost housing in hot, humid Africa. PLOS Medicine in press

6. Nieto-Sanchez et al (2015). Positive deviance study to inform a Chagas disease control program in southern Ecuador. Mem Inst Oswaldo Cruz, Rio de Janeiro, 110 (3), 299-309.

7. Singhal A (2011). Turning diffusion of innovations paradigm on its head: the positive deviance approach to social change. In A Vishwanath, GA Barnett, The diffusion of innovations: a communication science perspective, Peter Lang, New York, p. 192-205.

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Appendix

From Housing and Malaria Consensus Statement Vector Control Working Group Roll Back Malaria November 2015https://malariaworld.org/sites/default/files/RBM%20VCWG%20Housing%20and%20Malaria%20Consensus%20Statement_final.pdf

What are the key unanswered questions that need to be addressed?

In order to provide appropriate guidance on the optimal design of new housing structures and incremental improvements to existing housing, the following need to be considered:

1. What architectural features are protective? Could these features be improved further, especiallythrough actions by house owners themselves?

2. What is the degree of protection against clinical malaria afforded by improved housing quality and modification of the peri domestic environment and how does this vary across eco‐ ‐epidemiological, socio economic and cultural settings?‐

3. What other critical elements do we need to learn about vector ecology in relation to housing and the peri domestic environment?‐

4. How does the cost of building improved housing compare with the cost of regular housing? What is the cost effectiveness of housing improvements?‐

5. Who is willing to pay for improved quality housing and how can this be tied to the perceived desirability of interventions, local values and market demand?

6. What is the most efficient way to scale up housing interventions? Can these be integrated into ‐existing local/national government development strategies?

7. Can we develop new materials and innovative ways of protecting people in their homes?8. What vector borne diseases other than malaria does improved quality housing protect against?‐9. How does house improvement interact with indoor interventions like IRS/LLINs?10. What is the impact of screening and closing eaves against mosquitoes on ventilation and risk of

other diseases, such as respiratory disease?11. How can existing legislation on housing be reviewed/enforced to influence design the projected

new housing units for better protection from vector borne diseases?‐12. How do we address the urban and peri urban environments with regard to housing, ‐

infrastructure, water/sanitation and vector borne diseases?‐

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