Tag Archives: Slums

Worm Wars Continued

We have discussed results of deworming before and argued that it is important to treat at cluster level because of rapid re-infection from reservoirs in soil. A recent important meta-analysis compares deworming targeted at children versus a community-wide intervention.[1] It finds that community-wide approaches are more effective than treatment targeted at children for roundworms (Ascaris) and hookworms (Ancylostoma), but not whipworms (Trichuris). This finding is consistent with the much greater efficiency of the medicine in the former two worm types. The relative effect was greater in roundworms (odds ratio >16) than the more dangerous hookworms (OR >4), consistent with the shorter life-span of hookworm eggs than of roundworm eggs. These are important findings, but there is a worry that resistance may emerge with mass treatment. It would be interesting to see whether any studies have been done in slum populations specifically.

— Richard Lilford, CLAHRC WM Director


  1. Clarke NE, Clements ACA, Doi SA, et al. Differential effect of mass deworming and targeted deworming for soil-transmitted helminth control in children: a systematic review and meta-analysis. Lancet. 2017; 389: 287-97.

Let the Second Sanitary Revolution Begin

Despite the gains in recent years, far too many children still die before their fifth birthday. Childhood mortality in low income countries is 76 per thousand live births compared with 7 per thousand in high income countries.[1] Now that pneumococcal vaccine is in a widespread use we may expect diarrhoea to take over from pneumonia as the number one killer of children. Certainly in slums – soon to be home to over 1 billion people – diarrhoea is the greatest threat not just to life, but also to child health. Diarrhoea predisposes to chronic enteropathy, especially in malnourished children, which in turn predisposes to stunting and perhaps reduced cognitive development.[2]

But it does not have to be this way. The first ‘sanitary revolution’ in the second half of the 19th century in Europe and North America yielded massive gains in child survival.[3] Less than 4% of all development assistance has been allocated to urban water and sanitation improvement over the last few decades, according to Prof David Satterthwaite. Moreover, it is not as though Europe and America were awash with money; the per capita GDP of Britain in the 1860s ($703.1)[4] was roughly equivalent to that of Rwanda today ($697.3).[5] This suggests that a lack of political will is also to blame for poor sewage and water installations in modern day slums. And the pitiful state of sanitation in modern slums has been thoroughly documented.[6] Hardly surprisingly, improving sanitation is the number one priority for people who live in slums.[7] Water and sanitation is not a middle-class concern foisted on slum dwellers; it is a critically important issue that results in millions of child deaths and that local people want tackled.

There are of course barriers to tackling this problem relating to relative powerlessness of people in slums, poor local governance, immature financial markets, and so on. But there is another problem that is created entirely by a certain type of armchair academic – this is the pernicious idea that nothing can be done pending improvements in local and national governance. Such people argue that it is first necessary to improve security of tenure, functioning financial markets, and so on. An extension of this argument, for which empirical support is absent, is that water and sanitation is not enough; it must be part of an improvement in the whole slum ‘nexus’ to include solid waste disposal, street drainage, home improvement, etc. We cannot wait for extractive elites to disappear, the judiciary to be made independent, or every slum holder to achieve title before acting; Paris famously installed a functioning sewage system during the dictatorship of Napoleon the third following his coup d’état. Fortunately water and sanitation was prioritised at a recent WHO Technical Working Group on “Addressing Urban Health Equity Through Slum Upgrading” attended by the CLAHRC WM Director.

So, let the water and sanitation revolution begin. Let it be driven by political and social zeal but do not let it be undisciplined, and let us never forget that water and sanitation is a socio-technical innovation – it needs to be supported (ideally initiated) by local people themselves. Ensuring proper use and maintenance of sanitary facilities requires alignment of supply and demand.

A number of international organisation promote water and sanitation in low- and middle-income countries, for example the UN-HABITATs Water and Sanitation Trust Fund. But good intentions are not enough when it comes to sanitation – even where sanitation and water have been improved, the benefits on health are often nugatory.[8] [9] This is because the installations are inadequate, and/or because facilities are underused or poorly maintained. It is thus crucially important that interventions meet local needs, that they can be maintained, and that their effects in reducing exposure to infection and improving health are evaluated. Installation of improved water and sanitation utilities needs to be accompanied by research into how to make this socio-technical intervention work well and also summative evaluation of the effects on health and well-being.

— Richard Lilford, CLAHRC WM Director


  1. World Health Organization. Under-five mortality. WHO, 2016.
  2. Grantham-McGregor S, Cheung YB, Cueto S, Glewwe P, Richter L, Strupp B. Developmental potential in the first 5 years for children in developing countries. Lancet 2007; 369: 60–70.
  3. Szreter S. The Population Health Approach in Historical Perspective. Am J Public Health. 2003; 93(3): 421-31.
  4. Broadberry S, Campbell B, Klein A, Overton M, van Leeuwen B. British economic growth and the business cycle, 1700-1870. 2011. Working Paper.
  5. The World Bank. GDP per capita (current US$). 2016.
  6. Ezah A, Oyebode O, Satterthwaite D, et al. The history, geography, and sociology of slums and the health problems of people who live in slums. Lancet. 2016. [ePub].
  7. Parikh P, Parikh H, McRobie A. The role of infrastructure in improving human settlements. Urban Design Planning, 2012; 166; 101-18.
  8. Wolf J, Prüss-Ustün A, Cumming O, et al. Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: systematic review and meta-regression. Trop Med Int Health. 2014; 19(8): 928-42.
  9. Fewtrell L, Kaufmann RB, Kay D, Enanoria W, Haller L, Colford JM, Jr. Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis. Lancet Infect Dis. 2005; 5(1): 42-52.

Systematic Review of Community Interventions – Essential Reading for All Applied Health Researchers – in Fact All Applied Researchers

Consider a non-governmental organisation (NGO) dedicated to improving welfare for those who live in African slums. How could the NGO proceed?

  1. Conduct a survey, find that sanitation is the most pressing problem across the majority of slums, and involve communities in the design and implementation of a system of latrines, pipes and treatment plants – a strategy shown to be effective in the literature.
  2. Consult with slum communities to find out their concerns and then co-design bespoke solutions according to local priorities – a sanitation system here; garbage removal system there; micro-finance elsewhere.
  3. Engage with local communities to increase their capacity and self-confidence. For example, by replicating the famous Detroit soup kitchen model.[1] Then let them be the architects of their own fate.

These are all very different, yet all go under the title “Community Interventions”. In a massive systematic review of controlled studies,[2] O’Mara-Eves et al. found that community interventions are effective compared to no community intervention, and many of the studies are of high quality. Hardly surprisingly, more sustained interventions are more effective than those of shorter duration. The take home message is that community activation is a good thing, notwithstanding a few situations where it may have an effect opposite to that intended.[3] As to which of the above three types is best, “no man knoweth it,” but one assumes that different modes suit different circumstances. For example, the CLAHRC WM Director would not recommend method three above, since slum residents generally do not have sufficient disposable wealth to be the architects of their own fate.

— Richard Lilford, CLAHRC WM Director


  1. Fenton-Smith R. Can Soup Change the World? BBC News. 13 March 2015.
  2. O’Mara-Eves A, Brunton G, McDaid D, et al. Community Engagement to Reduce Inequalities in Health: A Systematic Review, Meta-analysis and Economic Analysis. Public Health Research No. 1.4. Southampton, UK: NIHR Journals Library, 2013.
  3. Lilford RJ. Adverse Effects of Well-Intentioned Interventions to Improve Outcomes in Adolescence. CLAHRC WM News Blog. Jan 15 2016.

Poverty and Cognitive Function

It would appear that people who are chronically poor have lower cognitive functioning than the well-off.[1] Of course, which way round causality is working is not clear from this finding alone. However, even temporary poverty appears to affect cognitive reasoning, even if nutrition, time to complete the cognitive test, and work-effects do not vary. This latter study was based on Indian farmers tested at various points as their wealth changed across the seasons.[2] The authors postulate that the stress associated with poverty consumes mental resources that are not available for other concerns. These results provide a further argument for focussing resources on the poorest of the poor. For instance, people in registered slums in India have many amenities that are denied those in unregistered slums.[2] It would be better to spread meagre resources even more thinly in order to provide at least some help those who are poorly equipped to help themselves.+

— Richard Lilford, CLAHRC WM Director


  1. Mani A, Mullainathan S, Shafir E, Zhao J. Poverty Impedes Cognitive Function. Science. 2013; 341: 976-80.
  2. Subbaraman R, O’Brien J, Shitole, T, et al. Off the map: the health and social implications of being a non-notified slum in India 2012. Environ Urban. 2012; 24(2): 643-63.

Further Evidence from Informal Settlements

At last slum health, featured in previous blogs, is starting to receive the attention it deserves. A recent report on the Mathare settlement in Nairobi, Kenya [1] correlates how far a person lives from a public toilet and risk of disease. The further a person lives from the facility, the more likely they are to be chronically unwell, especially with diarrhoeal diseases and childhood stunting. As readers know, poor nutrition and sanitation create a vicious circle. Also, the risk of violence against women rises with distance from a public facility. Clean water and sanitation remain huge challenges for slum dwellers. Improved sanitation would also produce an educational and economic dividend. Meanwhile toilet design has improved, for example, with the invention of the composting toilet, so cost-effective, logistically feasible improvements are possible and likely to be highly cost-effective. The CLAHRC WM Director liked this paper because it integrated disease surveillance, geospatial mapping, and the personal accounts of slum dwellers, to create a rich account of pathways to poor health.

— Richard Lilford, CLAHRC WM Director


  1. Corburn J & Hildebrand C. Slum sanitation and the social determinants of women’s health in Nairobi, Kenya. J Env Public Health. 2015. [ePub]

Slums – Exploding Urban Myths!

The CLAHRC WM Director has recently returned from a two week attachment to the African Population Health Research Center (APHRC) in Nairobi. He stayed in the home of the Director, Dr Alex Ezeh, and his charming wife Nkee, to whom he extends his sincere thanks. APHRC is the foremost African centre for the study of slums*. The APHRC were among the first centres to question the idea (discussed in a previous post) that slums provide a frequent conduit from rural poverty to middle class urban life. In fact, for a large proportion of families, they are a sink; three generations can frequently be seen living in a single dwelling.

The APHRC have also exploded another myth – that while urban poverty appears more extreme than rural poverty to the casual observer, slum dwellers enjoy better health than their rural cousins. Research carried out by the APHRC showed that this was not the case for Kenya,[1] and this finding has since been replicated in Bangladesh.[2]

The Director visited the Viwandani slum in the company of APHRC staff with whom he is collaborating on a project on urban regeneration. Although a cursory inspection would suggest that one slum is much like another, deeper examination shows that this is not the case. Slum populations are more transitory in some places than others, suggesting that for some, slum life really is a step on the path to economic emancipation. There is a pronounced economic gradient within slums, with poverty increasing with distance from centres of employment. One thing that struck the Director was the need to pay for every item of service, including water and even access to the lavatory.

Despite the privations that people live under, and the malodorous crowded conditions outside, many slum dwellers maintain a remarkably high standard of personal hygiene, and the homes we were graciously invited to visit were absolutely spotless. The slum we visited had been exposed to a vigorous programme (in which APHRC is participating) promoting exclusive breast-feeding to the age of six months, and the babies we saw were sleek and healthy. One exception was a toddler with a crusty skin infection on his outer ear. The CLAHRC WM Director, pining after his days as a clinician, diagnosed impetigo and referred the child for urgent antibiotic treatment to reduce the risk of acute glomerulonephritis.

The health of slum dwellers has received much less attention than rural health – for example, there are upwards of 30 Health and Demographic Surveillance Sites (HDSS) in Africa, but until last year only one (managed by APHRC) in a slum area. You might ask what is different about slum vs. rural health – people in both areas are exposed to parasites, water-borne disease, and other afflictions of poverty. However, the spectrum of conditions differ and so do many of the solutions. Providing safe water and ensuring adequate garbage disposal are particular problems. So is the stress and danger of over-crowding, and the risk of fires and burns is high for many reasons. Slum health is mentioned in the Millennium Development Goal 7, but a recent Lancet editorial stated that this document “underestimated the magnitude of the problem by tenfold”.[3]

* Some people prefer the term “informal settlement”, perhaps because it is seen as less stigmatising or offensive to the people who live there. However, Africans speak of slums and this term is used in the research literature. Perhaps it is felt that a blander term would do more harm than good by ‘sanitising’ a harsh reality and reducing a sense of urgency?

— Richard Lilford, CLAHRC WM Director


  1. African Population and Health Research Center. Population and health dynamics in Nairobi’s informal settlements. Nairobi (Kenya): African Population Health Research Center. 2002.
  2. UNICEF. Understanding urban inequalities in Bangladesh: a prerequisite for achieving vision 2021. A study based on the 2009 multiple indicator cluster survey, 2010. [Online].
  3. The Lancet. Urban health post-2015. Lancet. 2015; 385: 745.

The Most Important Applied Research Paper This Year? Perhaps Any Year?

Walk through a poor rural or urban landscape and the vista seems to repeat itself unchanged. But delve deeper and differences appear. One robust finding from India is that poor Muslim children have a much better survival rate than poor Hindu children – childhood mortality is about one-fifth lower among Muslims. This finding is unaltered by adjusting for known confounders and, in any case, Muslim children in India are poorer and less educated than their Hindu peers. In development circles this is known as the “Muslim mortality paradox”. It was solved by Geruso and Spears in July this year [1] in a brilliant study based on the USAID Demographic Health Survey. Muslims are much less likely to defecate in the open than are Hindus. Hindus often regard defecation in the home as unclean and are more likely than Muslims to go outside to relieve themselves, even if the house is equipped with a functioning lavatory. The study shows a significant correlation between defecation in the open and mortality and confirms what has been thought by many politicians, right back to Mahatma Gandhi, who said “Sanitation is more important than independence”. I believe that we can draw a cause and effect inference from this data because:

  • It withstands adjustment for sex, mother’s education and wealth, and mother’s age at birth. In fact, controlling for education and wealth widens the gap in mortality between religions.
  • Muslims are no more likely to wash their hands, use soap or filter water than Hindus, and are less likely to have access to running water according to the data; again a bias against the hypothesis.
  • It has a good biological explanation. Chronic/recurrent infection/infestation causes stunting due to enteropathy [2] and perhaps a persistently altered microbiome.
  • The increased risk among Hindus who use a lavatory declines in proportion to the proportion of surrounding people who also use a lavatory.
  • Breastfed Hindu children experience much smaller increases in risk than non-breastfed Hindu peers – to me this was ‘the clincher’.

The effect of poor sanitation is so large, that it accounts for a greater quantum of mortality than the difference between the richest and poorest 20% of the population. The findings make the case for improved sanitation in all poor rural and urban areas of the world. In a previous blog I discussed failed approaches to improved health in slums – slum clearance just moves the problem elsewhere; land tenures creates slum-lords, etc. Behaviour change and other methods to improve sanitation could be the big breakthrough in improving lives of slum dwellers and rural poor people alike. CLAHRC Africa is already conducing a pilot study in West Africa, led by Dr Semira Manaseki-Holland, and we are aware of only three cluster intervention trials, all of which are use of solar-powered disinfection of drinking water.[3] [4] [5] However, the USAID Water, Sanitation and Hygiene (WASH) programme is co-ordinating further studies. We think that the step wedge design [6] is particularly suitable for evaluation in such interventions and they should include sound economic and educational end-points, along with health measures.

— Richard Lilford, CLAHRC WM Director


  1. Geruso M, & Spears D. Sanitation and health externalities: Resolving the Muslim mortality paradox. 2014. Working paper, University of Texas, Austin.
  2. Spears D, Ghosh A, Cumming O. Open Defecation and Childhood Stunting in India: An Ecological Analysis of New Data from 112 Districts. PLoS One. 2013. 8(9): e73784.
  3. du Preez M, McGuigan KG, Conroy RM. Solar Disinfection of Drinking Water In the Prevention of Dysentery in South African Children Aged under 5 Years: The Role of Participant Motivation. Environ Sci Technol. 2010; 44(2): 8744-9.
  4. du Preez M, Conroy RM, Ligondo S, et al. Randomized Intervention Study of Solar Disinfection of Drinking Water in the Prevention of Dysentery in Kenyan Children Aged under 5 Years. Environ Sci Technol. 2011; 45(21): 9315-23.
  5. McGuigan KG, Samaiyar P, du Preez M, Conroy RM. High Compliance Randomized Controlled Field Trial of Solar Disinfection of Drinking Water and Its Impact on Childhood Diarrhea in Rural Cambodia. Environ Sci Technol. 2011; 45(18): 7862-7.
  6. Hemming K, Lilford RJ, Girling AJ. Stepped-wedge cluster randomised controlled trials: a generic framework including parallel and multiple level designs. Stat Med. 2014

Are Slums Part of the Transition from Rural Poor to Urban Middle Class?

Successive waves of immigrants have arrived in East London over the 400-plus years since the Huguenots arrived following the revocation of the Edict of Nantes in 1685. Like their successors, they arrived impoverished, found work and moved on to a better life elsewhere. East London stayed the same, but the inhabitants progressed.

Nearly one billion people live in informal settlements or slums worldwide. Are these people in transition from rags to riches, or are they stuck in a poverty trap? Sadly, the evidence suggests that the second scenario is closer to reality. Poorly nourished, inadequately educated, chronically unwell and exploited by “slumlords”, they tend to sink, rather than rise, according to a recent review.[1] Work carried out by my collaborations at the Africa Population and Health Research Center (APHRC) in Nairobi confirms that net emigration from slums is a slow and uncertain business. Sojourn times are prolonged, often encompassing more than one generation.[2]

Various solutions have been proposed for this problem over the last 50 years – more or less sequentially:

  1. Slum clearance – hardly gets to the underlying cause.
  2. Benign neglect to halt immigration from the country – they still come.
  3. Investment in slums – may be the best option, but benefits often prove ephemeral, as in Jakarta.
  4. Land titling – often makes matters worse because “slumlords”, now with title deeds in their files, evict residents or raise rents.

The only thing that really works is a rising per capita GDP, as in China and India, but “trickle down” can take a long time.

Like many social phenomenon, the solutions are not straightforward. We would be grateful for further contributions to this debate. However, early education (and I mean really early) and improved sanitation/healthcare may be the best bet for now. Small effects are likely to be cost-effective, I would suggest.

— Richard Lilford, CLAHRC WM Director


  1. Marx B, Stoker T, Suri T. The Economics of Slums in the Developing World. J Econ Perspect. 2013; 27(4):187-210.
  2. African Population & Health Research Center – APHRC. KENYA – NUHDSS – Residency Table for all DSS Residents. 2014. [Online].

Do the Social Health Features of Slums Correlate to the West Midlands?

As we were chewing the fat over a cup of coffee, Richard Lilford, CLAHRC WM Director, told me about his recent visit to Kenya and a grant application he was consulting on. The application plans to look at interventions which aim to improve the diet of the people who lived in the slums around Nairobi. Many people who live in such slums buy their food from street vendors, as this minimises the effort and cost of cooking. In 2002 The International Food Policy Research Institute based in Washington, produced a report looking at the challenges and options for poor people living in cities in developing countries.[1] One study it looked at found that city residents in Nigeria spent up to 50% of their total food expenditure on street food and would often have less time available for buying and preparing food, greater exposure to advertising, and easier access to street food compared to poor people living in rural areas. People buying this street food are constrained by what the street vendors are selling, which usually contains high levels of salt, saturated fat and sugar.

This got me thinking – can we claim to have better diets in higher income countries? Is there any difference between me popping into my local fast food restaurant on the way home from work or ordering a takeaway because I cannot make the effort to cook, and the poor people in Nairobi who buy their dinner from street vendors? Gavin Rudge of the CLAHRC WM recently carried out a pilot study looking at the relationship between fast food provision and neighbourhood characteristics in the metropolitan boroughs of Sandwell and Dudley. Initial findings suggest that there is an association between neighbourhood deprivation and the density and proximity of fast food outlets. The density of fast food outlets increases with deprivation, in the most deprived areas your nearest fast food outlet is less than a 2 minute walk away. While local authorities in this country are already moving to place restrictions on new applications for fast food outlets, some areas are already saturated with them – this seems to be an idea that has come far too late. Instead, we need to change people’s individual behaviour and their food choices in order to improve their diet. Although Sandwell is currently saturated in fatty and greasy food choices, if residents decide to eat healthier then eventually the demand for fast food will go down and outlets will be forced to close or diversify into healthier options.

It seems to me that whether you are living in the slums of Nairobi or in an inner city within the UK, the social features around food choices are the same. I will be interested to see how the CLAHRC WM Director tries to tackle this problem in Africa – hopefully he can bring some insights back.

— Jo Sartori, CLAHRC WM Head of Programme Delivery


1: International Food Policy Research Institute. Living in the City: Challenges and Options for the Urban Poor. 2002. [Online].