Can improved housing reduce infectious disease in Sub-Saharan Africa?

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The Baisha family on the site of their new home in Nanguruwe village, southern Tanzania, December 2019

By: Otis Sloan Brittain, Project Architect, Ingvartsen Architects, Tanzania; Hannah Wood, Project Architect, Ingvartsen Architects, Tanzania; Jakob Knudsen, Architect, Owner of Ingvartsen Architects, Denmark. Dean, School of Architecture. The Royal Danish Academy of Fine Arts Schools of Architecture, Design and Conservation, Denmark; Salum Mushamu, Founder, CEO and Lead Consultant, CSK Research Solutions Ltd. Tanzania; and Lorenz von Seidlein, Associate professor, MORU Mahidol Oxford Tropical Medicine Research Unit, Thailand.

Sub-Saharan Africa will account for the majority of the world’s population growth over the coming decades, with the number of people expected to double to 2.1 billion by 2050. We estimate that this will necessitate the construction of over 400 million new homes. In rural regions, many families live in houses made from traditional wattle and daub construction which demand repair and reconstruction after each rainy season. When families upgrade to a modern house, they typically opt for a large single story, poorly ventilated structure made from concrete blocks with a fashionably tall roof.

Both upgraded and vernacular house styles appear to predispose residents to contracting vector borne, enteric, and respiratory diseases. Thick walls absorb heat during the day and radiate it into the home at night, which deters occupants from using bednets, therefore increasing the risk of malaria transmission. Ground-level bedrooms have higher mosquito densities, which also increases the risk of contracting vector borne infections. Cooking is generally done on open fires within poorly ventilated spaces, which can lead to respiratory health issues, especially among women and children. Surfaces are generally made from compacted mud that is difficult to clean, which alongside open pit latrines, inadequate water supply and minimal sanitation, leaves families susceptible to diarrhoea and other enteric infections. The health consequences of building in this way are most severely felt in rural regions, such as Mtwara in southern Tanzania, where families have limited access to public health services.

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Drone shot of the Chekeleni village, where houses number 099 and 100 are under construction, August 2019

A body of emerging research suggests that well-designed housing can affect the three most common causes of child morbidity in Sub-Saharan Africa—malaria, enteric infections and respiratory infections. Danish architecture studio Ingvartsen, in collaboration with the University of Oxford, MORU and CSK Research Solutions, are currently working on a randomized controlled open label trial in Mtwara, southern Tanzania, to estimate the health benefits of improved housing. Our study combines the research and insights of an interdisciplinary team of architects, physicians, entomologists and social scientists, with an aim to offer communities in Sub-Saharan Africa a selection of alternative, robust and low-cost home construction ideas which have a measurable effect on family health and wellbeing.

The planning phase of the study involved initial statistical analysis to determine the appropriate sample size, followed by village surveys conducted across the Mtwara region. Fieldworkers then visited every household in each of the study villages to collect data about family composition, socioeconomic standards and living conditions. Families who fit the project inclusion criteria[i], and who opted to be part of the study, were entered into a lottery held in their village to win a new home (previous experience from the Magoda project in Tanga has shown that the lottery method was feasible and well accepted).

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Prototype house at the Star Home Project test site in Mtwara town, March 2020

The design of the prototype home and latrine was developed by architects Jakob Knudsen, Hannah Wood and Otis Sloan Brittain in close collaboration with the wider project team. It was inspired by 10 homes previously built by Ingvartsen in the Tanga region of northern Tanzania and construction techniques adapted for comparably hot, tropical climates in South-East Asia.

Key architectural elements to improve family health include: orientation to provide optimal shading throughout the day; a metal roof with closed eaves; an air permeable façade with openings screened from insects; a raised concrete ground floor which can be easily cleaned; a screened indoor cooking area with means to remove smoke; a protected lockable storage area; sleeping areas with bednets raised to the first floor[ii]; a water harvesting system which allows for the collection of rainwater from the roof; a solar panel system capable of lighting and charging mobile devices, and a ventilated pit latrine.

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A prototype ventilated pit latrine at the Star Home Project test site in Mtwara town, April 2020

Prior to constructing the 110 houses across 60 villages, 3 prototype designs and 2 test latrines were constructed on a site in Mtwara town to explore climatic performance, local construction capacity and the affordability of each design. The chosen prototype house and latrine design was constructed for $9000 in total, and it is expected that at scale the houses and latrines can be built for $6000 to $8000. Following the completion of the construction phase of the project, ancillary economic and social science studies will be undertaken by a health economics team at the Mahidol Oxford Research Unit.

In parallel with the ongoing construction of the houses in the villages, lotteries are currently underway to select 440 comparative control houses to be part of the study. Between October 2020 and October 2023, 1650 children living in the 110 new homes and 440 control houses will receive weekly visits from a fieldworker. Each family is asked whether any child living in the household has been unwell since the last visit, and sick children will be specifically checked for malaria, respiratory tract infections and enteric infections. All children participating in the trial will be offered medical assistance for the duration of the study period.

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Surveying the site of house 015 in Kinyamu village, May 2019

From a public health perspective, the study is novel as it investigates a suite of interventions which encompass the concept of a ‘healthy home’: in our study the house itself is the intervention, similar to the vaccine in a vaccine trial. Rather than focussing on a single disease in isolation, our study explores how children can be protected from the three most common causes of child morbidity and mortality in Sub-Saharan Africa, while addressing the overall wellbeing of the family. We see alternative approaches to malaria control and elimination as a priority as current gains in reducing malaria transmission may be lost with the increasing prevalence of insecticide resistance and the spread of antimalarial resistance.

We hope the study will signal to policy makers that investing in well-built affordable housing can have a measurable impact both on public health and quality of life for communities living in rural regions. If a home has low operational and maintenance costs, time and resources otherwise spent on activities such as house rebuilding, dealing with preventable illnesses or collecting water will be unlocked, enabling families to lift themselves out of poverty long-term.

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A LGS frame of a study home being erected by local craftsmen in Lilido village, February 2020

 

[i] The project inclusion criteria include: that the household includes at least 3 children under 12 years, the household members intend to remain in the village for at least the coming two years, that they have basic housing and a plot to build a house on.

[ii] Research suggests that elevating the house structure and using permeable walls promotes airflow, reduces indoor temperature and optimises overall indoor climate. It is also likely that raising the house above ground level will reduce the entry of Anopheles gambiae mosquitoes, as current research suggests the major African malaria vector, since most fly no more than one metre above the ground (Lindsay SW, Emerson PM, Charlwood JD. Reducing malaria by mosquito-proofing houses 2002; 18: 510-4, Gillies MT, Wilkes TJ. The vertical distribution of mosquitoes flying over open farmland in the Gambia. Trans Roy Soc Trop Med Hyg 1974; 68(4): 268-9.)

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