Introduction

Top Abstract Introduction Participants and methods Results Discussion References

Poor quality housing is generally accepted to be an important contributor to ill health.¹ Rates of disease have been associated with the quality and specific attributes of a house as well as the conditions that those qualities impose.^2-11

Although the importance of housing for health is recognised, ^{1 12 13} few well designed studies have quantified this impact, especially in the developing world. The objective of this study was to assess the impact on children's health of a housing improvement project in rural Malawi. We examined the effect on illness of living in improved housing compared with living in traditional housing.

	Participants and methods

Top Abstract Introduction Participants and methods Results Discussion References

The study was conducted in collaboration with Ekwendeni Hospital, Homeless International UK, and Habitat for Humanity International in the town of Ekwendeni, Malawi. Traditional houses in the area are constructed of mud brick walls with thatch roofing, hard packed mud floors, and possibly a pit latrine. Houses are usually about 25 m² and consist of two or three rooms. Houses constructed under the Habitat for Humanity programme in Ekwendeni have fired mud bricks, tile roofing, concrete foundation, and a pit latrine. Habitat houses have a mean size of 30 m² and three rooms. The cost of a habitat house at the time of the study was about $550 (£370), offset by a 10 year no interest loan. Habitat houses were built next to or replaced the traditional house of the intended owner and were non-systematically dispersed throughout the communities among traditional houses.

Participants in the habitat programme were selected by a village habitat committee. Applicants had to be unable to provide adequate housing for themselves because of financial, social, or physical reasons and to have shown their commitment to the programme by spending a standardised amount of time helping to build another applicant's house.

Sample
We used data from two surveys conducted in March and August 1997. Households for the first survey were randomly selected from a list of about 300 habitat homes built at that time. Households for the second survey were selected from the same list, but houses surveyed in March were excluded. At enrolment, we asked permission to complete the survey, collect water samples from the household storage container and water source to test for coliforms (Hach Bromcresol purple broth and broth with methylumbelliferyl--D-glucuronide presence or absence method), collect blood from the finger of children younger than 5 years, and give a medical examination. Once we had collected data from the habitat house, we obtained data from the closest traditional house.

Instrument and measures
We used the illness recall method to assess the health of children under 5 years. In the first survey mothers reported symptoms experienced during the past month. In the second survey they were asked to report symptoms in the past two weeks. Analyses stratified by recall period found that trends were consistent across the two surveys so we combined the data. All children were screened for malaria by blood film examination and examined by a doctor to detect palpable spleens.¹⁴

Analysis of data
We compared habitat and traditional households with bivariate analyses using EpiInfo version 6.0. We then used the Genmod procedure to fit generalised linear models on correlated data using SAS for Windows (version 6.11). The Genmod procedure fits models using maximum likelihood estimation, and we used it to account for some households having more than one child, to adjust for potential confounding factors, and to test for interactions.

	Results

Top Abstract Introduction Participants and methods Results Discussion References

Table 1 shows the numbers of houses included in each survey. We found no significant differences in socioeconomic and demographic variables between the habitat and traditional houses (table 2). Overall, the comparability of the non-housing socioeconomic characteristics in the two groups suggests that any differences between the two groups are likely to be due to differences in housing.

Table 3 shows the proportion of children under 5 years with various illnesses. The percentage of children with any or each of the three illnesses is lower in the habitat houses than the traditional houses.

Table 4 shows the results of the multivariate analysis to determine the relation between housing and the health of children under 5 years old. Although none of the unadjusted odds ratios are significant, all the relations are roughly of the same magnitude and direction. When access to safe water was controlled for, children in habitat houses were 45% less likely to have any illnesses (odds ratio=0.55, 95% confidence interval 0.34 to 0.75) than children in traditional houses. The incidence of respiratory infection was also significantly reduced among children in habitat houses.

The reduced rate of overall illness in children in habitat houses remained after adjustment for other potential confounding factors (0.56, 0.35 to 0.91; table 4). However, the effect on individual illnesses was not significant. Interactions between housing type and water source and between housing type and method of disposal of excreta were not significant.

	Discussion

Top Abstract Introduction Participants and methods Results Discussion References

This study shows that the five year housing programme significantly improved the health of children under 5 years old. Children living in an improved house had 44% reduced odds of respiratory infection, gastrointestinal illness, or malaria. Access to a safe water source, having above average knowledge about the methods used to prevent malaria, and owning a private latrine were also significantly associated with lower odds of some illnesses. These associations were independent of the level of education and occupation of the head of the household. The size of the effect of housing was roughly equivalent for respiratory infections, gastrointestinal disorders, and malaria. Incorporating bed nets or ceilings into houses may increase the health benefits of better housing by reducing malaria further.

Our investigation has several limitations. Firstly, there is potential for bias in the selection of people into the housing programme by the habitat village committee. The similarity in the sociodemographic profiles between the two groups, however, suggests selection bias was minimal. Secondly, mothers could have misreported respiratory infection and gastrointestinal disorders. However, the hospital had a long association with the communities in this area, which has resulted in trust between the interviewer and interviewee. The final limitation is that disposal of excreta was improved in some traditional houses, with 38% having private latrines. We controlled for method of disposal in the final model.

The effect sizes in our study are similar to those reported for many other health interventions, such as improving water and sanitation, that receive more attention and financial support. Programmes in which simultaneous improvements in housing, water, and sanitation are combined with education on how to take advantage of these improved resources are likely to have the greatest effect on health.

	Acknowledgments

Contributors: CGW and MWY had the original idea for the study, contributed to its design, and coordinated the collection, compilation, and checking of the data. DGS contributed to the design of the study. CGW directed and DGS supervised the analyses. CGW wrote the first draft of the manuscript, and DGS and MWY reviewed and contributed to subsequent drafts. CGW and DGS are the guarantors.

	Footnotes

Funding: The study was funded by Hermann Boozer-Noether Fund, Emory University, a Gangarosa scholarship NIH R29-HD33468, and Homeless International.

Competing interests: None declared.

	References

Top Abstract Introduction Participants and methods Results Discussion References

1.	United Nations Centre for Human Settlements. An urbanizing world: global report on human settlements. Nairobi: UNCHS, 1996.
2.	Pirhonen I, Nevalainen A, Husman T, Pekkanen J. Home dampness, moulds and their influence on respiratory infections and symptoms in adults in Finland. Eur Resp J 1996; 9: 2618-2622[Abstract].
3.	Sharma S, Sethi GR, Rohtagi A, Chaudhary A, Shankar R, Bapna JS, et al. Indoor air quality and acute lower respiratory infection in Indian urban slums. Environ Health Perspect 1998; 106: 291-297[Medline].
4.	World Bank. World development report: investing in health. New York: Oxford University Press for World Bank, 1993.
5.	Manun'ebo MN, Haggerty PA, Kalengaie M, Ashworth A, Kirkwood BR. Influence of demographic, socioeconomic and environmental variables on childhood diarrhoea in a rural area of Zaire. J Trop Med Hyg 1994; 97: 31-38[Medline].
6.	Wright CE, el Alamy M, DuPont HL, Holguin AH, Hsi BP, Thacker SB, et al. The role of home environment in infant diarrhea in rural Egypt. Am J Epidemiol 1991; 134: 887-894[Abstract/Free Full Text].
7.	Mara DD, Alabaster GP. An environmental classification of housing-related diseases in developing countries. J Trop Med Hyg 1995; 98: 41-51[Medline].
8.	Schofield CJ, White GB. Engineering against insect-borne diseases in the domestic environment, house design and domestic vectors of disease. Trans R Soc Trop Med Hyg 1984; 78: 285-292[CrossRef][Medline].
9.	Gamage-Mendis AC, Carter R, Mendis C, De Zoysa PK, Herath P, Mendis KN. Clustering of malaria infections within an endemic population: risk of malaria associated with the type of housing construction. Am J Trop Med Hyg 1991; 45: 77-85.
10.	Gunawardena DM, Wickremasinghe AR, Muthuwatta L, Weerasingha S, Rajakaruna J, Senanayaka T, et al. Malaria risk factors in an epidemic region of Sri Lanka, and the impact and cost implications of risk factor-based interventions. Am J Trop Med Hyg 1998; 58: 533-542[Abstract].
11.	Ko YC, Chen MJ, Yeh SM. The predisposing and protective factors against dengue virus transmission by mosquito vector. Am J Epidemiol 1992; 136: 214-220[Abstract/Free Full Text].
12.	United Nations Habitat II Conference. Report of the United Nations conference on human settlements (habitat II). Istanbul: United Nations Development Programme, 1996.
13.	World Health Organization. Urbanization and its implications for child health. Geneva: WHO, 1988.
14.	Genton B, Smith T, Baea K, Narara A, al-Yaman F, Beck HP, et al. Malaria: how useful are clinical criteria for improving the diagnosis in a highly endemic area? Trans R Soc Trop Med Hyg 1994; 88: 537-541[CrossRef][Medline].

(Accepted 23 January 2001)