Essay Slum Health: From Understanding to Action Alon Unger*, Lee W. Riley

“Slums are a manifestation of the two main challenges facing human settlements development at the beginning of the new millennium: rapid urbanization and the urbanization of poverty.”

Anna Kajumulo Tibaijuka, Executive Director, United Nations Human Settlements Programme [1] doi:10.1371/journal.pmed.0040295.g001 “Jo lives—that is to say, Jo has not yet died—in a ruinous place, known to the like of him by the Figure 1. Kibera Shantytown in Nairobi, Kenya name of Tom-all-Alone. It is a black, dilapidated Home to nearly 1 million residents on the outskirts of Nairobi, Kibera is the world’s second largest street, avoided by all decent people…Now, these slum. Photo by Alon Unger. For a virtual tour, see: http://www.amref.org/index.asp?PageID=432 tumbling tenements contain, by night, a swarm of misery…As, on the ruined human wretch, vermin the least developed countries’ urban on these neglected communities and parasites appear, so, these ruined shelters have population live in slums [1]. Today’s already limited health care resources. bred a crowd of foul existence that crawls in and slums are unprecedented in their sheer In this essay, we show that the defining out of gaps in walls and boards; and coils itself magnitude, their rapidity of growth, physical and legal characteristics of to sleep, in maggot numbers, where the rain drips and their worldwide distribution in; and comes and goes, fetching and carrying [1,5]. They represent a fundamental Funding: The authors received no specific funding fever…” transformation of the physical and for this article. social environment of urban life and Charles Dickens, Bleak House [2] Competing Interests: The authors have declared human health. that no competing interests exist. his year, 2007, marks the first Like Dickens’ Tom-All-Alone, slums Citation: Unger A, Riley LW, et al. (2007) Slum health: time in human history that are synonymous with squalid living From understanding to action. PLoS Med 4(10): e295. Tthe majority of the world’s conditions. A visit to the favelas of doi:10.1371/journal.pmed.0040295 population will live in cities [3]. The Rio de Janeiro, the shantytowns of Copyright: © 2007 Unger and Riley. This is an United Nations (UN) projects the Nairobi, or the jhopadpatti of Mumbai open-access article distributed under the terms world’s urban population to grow by shows that a slum, by any name, is of the Creative Commons Attribution License, an unhealthy place to live (Table 1, which permits unrestricted use, distribution, 2 billion before 2030. More than 90% and reproduction in any medium, provided the of this growth will take place in the Figures 1 and 2; for a virtual tour of original author and source are credited. least developed countries [4], and one such slum, see: http://www.amref. Abbreviations: DALY, disability-adjusted life year; will be concentrated in the bleakest org/index.asp?PageID=432). Many TB, tuberculosis; UN, United Nations parts of the city—human settlements health outcomes are worse in slums known as slums. Already nearly a third than in neighboring urban areas or Alon Unger is with the Departments of Medicine and Pediatrics, University of California, Los Angeles, Los (32%) of the world’s population and even rural areas [6–8]. Moreover, the Angeles, California, United States of America. Lee W. more than three-fourths (78%) of formal health sector encounters slum Riley is with the Division of Infectious Disease and residents only when they develop late- Epidemiology, School of Public Health, University of California, Berkeley, California, United States of stage complications of preventable America. The Essay section contains opinion pieces on topics chronic diseases, as we have described of broad interest to a general medical audience. * To whom correspondence should be addressed. elsewhere [9]. This takes a costly toll E-mail: [email protected]

PLoS Medicine | www.plosmedicine.org 1561 October 2007 | Volume 4 | Issue 10 | e295 California. The built environment Table 1. Slums Go By Many Names is also directly related to accidental Language or Region Term injuries, such as falls and burns [19]. French bidonville, taudis, habitat précaire, habitat spontané, quartier irrégulier Physical characteristics of slums not Spanish asentamiento irregular, barrio marginal, barraca, conventillos, colonia only magnify the consequences of popular, villa miseria, ciudad perdida natural or man-made disasters, but also German elendsviertel hinder rescue efforts [20]. Arabic mudun safi, lahbach, brarek, medina achouaia, foundouks, tanake, aashwa’i Overcrowding. Slum dwellings have Russia/Eastern Europe trushchobi, kartonsko naselje high occupancy rates in all-purpose Portuguese favela, quartos do slum, morro, loteamento, cortiço, comunidade Turkish gecekondu rooms. Cooking, sleeping, and living 2 English hood, ghetto, squatter camp, shantytown with 13.4 people per 45 m room, as South Asia chawl, ahata, katra, bustee, katchi abadis, watta, pelli gewal, jhopadpatti in the slums of Kolkata, India [21], Africa umjondolo, mabanda, kijiji places residents at risk of respiratory infections, meningitis, and asthma From [1]. doi:10.1371/journal.pmed.0040295.t001 [22,23]. In Manila, the Philippines, children living in squatter settlements slums profoundly affect the health of forces residents to occupy unused are nine times more likely than other these communities and may also serve or undesirable land. For example, children to have tuberculosis (TB) as potential targets for immediate between 1991 and 1997, 1.5 million [24]. Epidemic-prone infections like intervention. and 1 million people were evicted from pertussis cluster in areas of urban central areas of Shanghai and Beijing, poverty [25], and overcrowding Defining Slums and the Challenge respectively [13]. Such dislocations may even fuel potentially emerging of Slum Health out of the city center force large epidemic diseases like SARS or In 2002, the UN operationally numbers to commute longer distance influenza [26]. Crowding is also defined slums as those communities to their original place of work, where associated with rheumatic heart disease, characterized by: insecure residential they brave the road, by foot or in a chronic and debilitating disease status, poor structural quality of overcrowded and dangerous vehicles, facilitated by increased transmission of housing, overcrowding, and inadequate putting themselves at risk for road- group A Streptococcus pyogenes infections access to safe water, sanitation, and traffic injuries [14]. Slum locations and lack of early treatment [27]. other infrastructure [10] (Table 2). may be unused or undesirable because Inadequate access to safe water. The 2003 UN report, The Challenge of their hazardous geography, such Poor water quality is a leading cause of Slums, is the most comprehensive as landslide- or flood-prone areas, of morbidity and mortality worldwide account of the demographic and or unsafe or polluted environments. and a defining danger of living in socioeconomic indicators of slums Moreover, their residential status slums [28]. Many life-threatening worldwide [1]. It details not only the limits their ability to fight for the right infectious diseases are associated high concentration of poverty and to a safe environment. In 1984, the with contaminated water in slums, substandard living conditions in slums, accidental release of methyl isocyanate such as cholera and hepatitis (Table but also the insecurity of tenure and from a pesticide factory in Bhopal, 2) [29]. Lack of access to water also marginalization from the formal sector, India killed more than 20,000 slum restricts water intake, sources for infant including basic health services. residents; the factory was built after formula or cooking, bathing and the settlement had already been in personal hygiene. Infrequent bathing Conditions of Slum Life and existence [15]. Even in the United is associated with scabies and bacterial Health—Using the UN Operational States, Hurricane Katrina unmasked skin infections, a subset of which (i.e., Definition the vulnerability of residents of poor group A streptococcus) can lead to Slums are areas of “concentrated neighborhoods in flood-prone areas acute glomerulonephritis [30]. disadvantage” [11]. The physical and and also the neglect of this population Inadequate access to sanitation legal characteristics enumerated by by political institutions [16,17]. and other infrastructure. The lack the UN are intimately related with Poor structural quality of housing. of infrastructure affects all aspects population composition and dynamics, Slum housing is densely packed and of life, including waste collection social environment, poverty, and poorly built with substandard or and sewers, public transportation, marginalization. Health comparisons of even flammable materials. Houses policing, education, and electricity rural versus urban areas, or emphasis built against hillsides are subject to supply. Five million slum residents on the urban health “penalty” or landslides during heavy rain, and live without toilets in Mumbai; if each “advantage,” do not highlight the inferior building standards cause many person defecates half a kilogram specific health determinants of slums thousands of deaths from earthquakes, per day, 2.5 million kilograms of [12]. Here, we use the UN operational especially where urbanization and human waste contaminate their criteria to show that the conditions poverty collide [18]. In Bam, Iran, poor environment each day [31]. While of slum life have a direct impact on structural quality of housing played a diseases like leptospirosis in developed the health and well-being of these major factor in the earthquake-related countries generally occur as a result communities (Table 2). deaths of 32,000 people in 2003. Days of recreational water sports [32], Insecure residential status. The earlier, an earthquake of a similar 95% of severe manifestations of this lack of secure land or housing tenure magnitude killed only two people in disease in Salvador, Brazil occur in

PLoS Medicine | www.plosmedicine.org 1562 October 2007 | Volume 4 | Issue 10 | e295 detailed urban health data masks gross health disparities within cities. Currently, most slum disease burden and mortality data are based on clinic, hospital, or national mortality registry data. This grossly underestimates the underlying medical conditions, such as hypertension, that give rise to the complications observed by the formal health sector, such as stroke [9]. The absence of detailed or accurate data limits the ability of officials to detect health threats or appropriately allocate resources. Prompt identification of local health concerns is the first step in any intervention. There is a pressing need for a new analytic framework to understand health in slums. Standard health metrics, such as disability-adjusted life years (DALYs) lost, do not account for the context in which diseases occur. The DALY for TB in a 25-year-old man doi:10.1371/journal.pmed.0040295.g002 in New York City is different than that Figure 2. A Jhopadpatti in Mumbai, India in a 25-year-old man in the Dharavi There are 6.7 million slum dwellers among Mumbai’s 12 million residents. In the Ganesh Murthy slum of Mumbai. Accepted indicators Nagar slum in the Colaba district, one resident noted, “We had one small, smelly toilet for a of socioeconomic status (e.g., income, population of 10 000. Women suffered the most because they had to relieve themselves in the education, occupation) are inadequate open, and could do so only in the early mornings or after dark” [43]. There are regular outbreaks of diarrheal diseases, leptospirosis, malaria, and dengue in Mumbai’s slums [4]. Photo by Lee Riley. in areas of generalized poverty and informal residence or work [39]. The social gradient within slums may be slum residents living in areas with close of accessible and utilized health care better indicated, for instance, by the proximity to open sewers and high rat services. difference in building materials (i.e., density [33]. Slums are also excluded mud versus brick) or number of meals from the benefits of formal policing, Meeting the Challenge of the per day. Slums are complex, and our and young men in the favelas of Brazil Slums efforts must match this complexity. are up to five times more likely to The determinants of slum health are Then we can better focus scarce die from homicide than their urban too complex to be defined by any resources on the most modifiable and counterparts [34]. Violence associated single parameter. Yet, they arise from relevant factors for improving health. with drug traffic between gangs or with a common physical and legal pedigree This will save time, money, and lives. the police create unsafe conditions for that concentrates the ill effects of Targeting relevant and modifiable all residents and pose a major barrier to poverty, unhealthy environments, and conditions of slum life. Slum-specific provision of public health interventions marginalization from the formal sector. information may reveal that health [35]. Violence towards women is also The promotion of urban health in the priorities in slums should be very associated with the absence of basic 21st century must take neighborhood- different than national or even local services like street lighting [36]. centered as well as person-centered urban ones. Improving health status Available health services are often approaches. We recognize that broad may require the simple acts of closing comprised of an inconsistent patchwork economic, social, and political forces open sewers to limit diarrheal disease, of public, private, and charity-based play an important role in the creation lighting footpaths to deter violence, providers. Inadequate or inappropriate and growth of slums, and addressing constructing barriers to prevent care at these places permits the these forces will take time. However, we falling injuries, or diverting run-off progression of preventable diseases, represent clinicians and public health or reinforcing dams to lessen loss of such as hypertension and diabetes, specialists, and therefore, our approach property and life from heavy rains. and increases the risk of drug-resistant focuses on immediate solutions that Some priorities, like addressing high infections, such as multidrug-resistant can dramatically improve health and rates of HIV in slums, may be the same TB [37]. Vaccination coverage in slums health disparities (Box 1). as for other communities; however, is markedly lower than in other urban Gather data on slum disease burden the solutions must be slum-specific areas due to inadequate infrastructure and intra-urban health disparities. [40]. These efforts can be made and a lack of community awareness Accurate health statistics in slums are without awaiting poverty alleviation. and mobilization [38]. Appropriate difficult to obtain, and health statistics Intervention trials in poor urban/slum interventions and treatments are only rarely report intra-urban differences. areas have already demonstrated that effective once provided in the context The inability to collect or analyze hand-washing with soap can reduce

PLoS Medicine | www.plosmedicine.org 1563 October 2007 | Volume 4 | Issue 10 | e295 Table 2. UN Operational Definition of Slums and the Physical, Legal, and Adverse Health Outcomes Characteristic Physical or Legal Definition Physical/Legal Outcome Adverse Health Outcomes

Insecure residential status u Households without: u Eviction u Poor access to health care services, traffic oformal title deeds to either land or residence u Exposure to toxic/chemical waste injuries oenforceable agreements as a proof of and pollution u Acute poisoning, respiratory diseases, cancer tenure u Low service utilization u Intentional injuries, STDs/HIV, unwanted pregnancy, substance abuse–related diseases Poor structural quality of u Households residing in hazardous sites: u Land and mud slides u Unintentional injuries housing ogeologically hazardous (landslide/ u Flooding u Leptospirosis, diarrheal diseases, cholera, earthquake/flood areas) u Fire malaria, dengue, hepatitis, drowning o industrial pollution u Vertical, multi-story housing u Falling injuries o unprotected hazards (e.g., dumps, railroads, construction u Burn injuries power lines) u Residence in or near dumps; u Households living in temporary and/or spontaneous combustion of dilapidated structures: garbage o inferior building materials (cardboard, corrugated tin, mud, low-grade concrete/ bricks) o substandard construction (e.g., inadequate foundation or support structures, insecure joints/connections) Overcrowding u Households with more than two persons per u Enhanced opportunity for disease u Tuberculosis and other respiratory illnesses, room or less than five square meters per person transmission meningitis, scabies, skin infections, bacterial pharyngitis, rheumatic heart disease Inadequate access to safe u Less than 50% of households have accessa: u Contaminated water sources u Diarrheal diseases, cholera, typhoid, hepatitis water o household connection u Water scarcity u Scabies, bacterial skin infections, acute o access to public stand pipe glomerulonephritis o rainwater collection Inadequate access to u Less than 50% of households have improved u Increased rat density u Typhus, leptospirosis, diarrheal diseases, sanitation and other sanitationb: u Open or broken sewers cholera, malaria, dengue, hookworm, infrastructure o public sewer u Suboptimal schools hepatitis, chronic respiratory diseases, growth o septic tank u Inadequate/inappropriate health retardation o pour-flush latrine care services u Under-utilization of services, maternal health o ventilated improved pit latrine complications, vaccine-preventable diseases, perinatal diseases, rheumatic heart disease, suicide u Poor access to health education u Drug-resistant infections, poorly controlled hypertension, diabetes, and other chronic illnesses

Oerational definition of slums adapted from UN sources [1]. aDefined as 20 liters/person/day, acceptable collection distance. bShared by maximum of two households. STD, sexually transmitted disease doi:10.1371/journal.pmed.0040295.t002 the risk of diarrheal diseases by up to mosques. This means finding people Involving residents is also an important 47% and could save a million lives [41]. where they congregate, be it bars in step in redressing the social exclusion, Compelling data like these can be used Venezuela or dance halls in Kenya. inequity, and disempowerment that to advocate for improved sanitation In particular, private pharmacies are characterize their situation. infrastructure and basic hygiene central to health care in slums [42] Interventions to improve the health supplies. and can play an important role in of slum dwellers are not cutting- From understanding to action. monitoring chronic diseases (e.g., edge science. Effective interventions Health officials, doctors, and public hypertension and diabetes) and involve not only treating disease but health specialists can take advantage of delivering health education in slums. also addressing the underlying social existing structures and social capital in It is more important than ever to and living conditions of slums. Many slums. Dense populations may not only enlist residents of slums as partners. solutions will require significant pose a risk, but also an opportunity—to In Mumbai, residents are instrumental multisectoral effort and resource efficiently reach a large, vulnerable in managing community toilets in a mobilization, which may be beyond our proportion of the population. We can nationwide project supported by the traditional role as health professionals. minimize the lack of access to health World Bank [43]. In Rio de Janeiro, This will require us to be students of services through innovative programs, community members educate their problems, not disciplines, and to work such as school-based vaccination or neighbors about HIV infection and closely with urban planners, engineers, outreach via churches, temples, and hand out condoms in markets [35]. and politicians to make the necessary

PLoS Medicine | www.plosmedicine.org 1564 October 2007 | Volume 4 | Issue 10 | e295 Box 1. Meeting the Challenge of Slums 11. Vlahov D, Freudenberg N, Proietti F, Ompad D, Quinn A, et al. (2007) Urban as Gather data on slum disease burden and intra-urban health disparities a determinant of health. J Urban Health 84: 16-26. • Establish routine disease surveillance within slum communities or at local clinics 12. Freudenberg N, Galea S, Vlahov D (2005) Beyond urban penalty and urban sprawl: Back • Ensure a safe environment for disease surveillance and reporting of illegal or informal to living conditions as the focus of urban residential status, without fear of reprisal health. J Community Health 30: 1-11. 13. Zhang Y, Fang K (2004) Is history repeating • Organize community planning groups for health care prioritization made up of itself? From urban renewal in the United States community leaders and representatives of local health professionals, high-risk groups, to inner-city redevelopment in China. J Plann Educ Res 23: 286-289. community-based organizations, and nongovernmental organizations 14. Ameratunga S, Hijar M, Norton R (2006) • Develop new analytical framework for understanding health outcomes in slums, Road-traffic injuries: Confronting disparities to address a global-health problem. Lancet 367: including new metrics for disease burden estimates based on slum-specific social and 1533-1540. physical parameters 15. Dhara VR, Dhara R (2002) The Union Carbide disaster in Bhopal: A review of health effects. Identify and target relevant and modifiable conditions of slums life Arch Environ Health 57: 391-404. 16. Nates JL, Moyer VA (2005) Lessons from • Focus on slum-specific health care needs, which may be very different than those in Hurricane Katrina, tsunamis, and other neighboring urban areas disasters. Lancet 366: 1144-1146. 17. McLellan F (2005) Hurricane Katrina: “A • Target immediately modifiable health risks, such as diverting sewage or run-off, speaking sight”, or, washday in Durant. Lancet waste disposal, installing public lighting, providing soap and hygiene education, and 366: 968-969. improving traffic safety 18. Jackson J (2006) Fatal attraction: Living with earthquakes, the growth of villages into • Involve auxiliary health care providers, such as private pharmacies and traditional megacities, and earthquake vulnerability in the modern world. Philos Transact A Math Phys healers Eng Sci 364: 1911-1925. Take action 19. Bartlett SN (2002) The problem of children’s injuries in low-income countries: A review. • Use existing structures and social capital in slums, such as community groups or Health Policy Plan 17: 1-13. religious institutions, and involve residents in design and provision of services 20. Sapir D, Lechat M (1986) Reducing the impact of natural disasters: Why aren’t we • Engage in multisectoral interventions, including professionals from urban planning, better prepared? Health Policy Plan 1: 118- 126. public works, engineering, and health sectors 21. Kundu N (2003) Urban slum reports: The case • Advocate for patients through public advocacy, political institutions, and reporting of Kolkata, India. Nairobi: United Nations. 22. Sharma S, Sethi GR, Rohtagi A, Chaudhary study results in internationally distributed professional journals A, Shankar R, et al. (1998) Indoor air quality and acute lower respiratory infection in Indian urban slums. Environ Health Perspect 106: changes. Health professionals can communities who have given us insight into 291-297. the challenges to good health that they face 23. Benicio MH, Ferreira MU, Cardoso MR, Konno also make important contributions SC, Monteiro CA (2004) Wheezing conditions as civic leaders when they organize every day. in early childhood: Prevalence and risk factors neighborhood associations and in the city of Sao Paulo, Brazil. Bull World References Health Organ 82: 516-522. resident advocacy groups, or act 1. UN-HABITAT (2003) The challenge of the 24. Fry S, Cousins B, Olivola K (2002) Health of themselves to represent the billion slums: Global report on human settlements. children living in urban slums in Asia and unheard voices of slum dwellers. Nairobi: United Nations. the near east: Review of existing literature 2. Dickens C (1853) Bleak House. London: and data. Environmental Health Project, Penguin Books. U.S. Agency for International Development. Conclusion 3. United Nations Population Division (2003) Available: http://www.ehproject.org/PDF/ We describe the challenges to good World urbanization prospects: The 2003 revision. 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World Health Organization (2004) Rheumatic immediately with life-saving effect. Our Verso. fever and rheumatic heart disease. Available: 6. Szwarcwald CL, Andrade CL, Bastos FI http://www.who.int/cardiovascular_diseases/ approach to slum health is neither (2002) Income inequality, residential poverty resources/trs923/en/index.html. Accessed 6 comprehensive nor exclusive. It is our clustering and infant mortality: A study in Rio September 2007. de Janeiro, Brazil. Soc Sci Med 55: 2083-2092. 28. World Health Organization (2003) Emerging simple goal to direct the attention 7. Sclar ED, Garau P, Carolini G (2005) The 21st issues in water and infectious disease. Available: and efforts of health professionals to century health challenge of slums and cities. http://www.who.int/water_sanitation_health/ the characteristics of slum life that Lancet 365: 901-903. emerging/emergingissues/en/. Accessed 6 8. Fotso JC (2006) Child health inequities in September 2007. profoundly affect health. 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