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The Social Determinants Of Schistosomiasis

23 Jan 2008

Source: WHO/TDR

Susan Watts

Social Research Center, American University in Cairo, PO Box 2511, Cairo 11511, Egypt

Working paper for the Scientific Working Group meeting on Schistosomiasis Research, convened by the Special Programme for Research and Training in Tropical Diseases, Geneva, 14–16 November 2005

Full text source: Scientific Working Group, Report on Schistosomiasis, 14–16 November 2005, Geneva, Switzerland, Copyright © World Health Organization on behalf of the Special Programme for Research and Training in Tropical Diseases, 2006, http://www.who.int/tdr/publications/publications/swg_schisto.htm

The Commission on the Social Determinants of Health (SDH) was launched by WHO in March 2005. Its mandate is to trace the pathways by which social determinants affect health status and outcomes. Of these determinants, poverty is the key. The Commission is also to recommend policies to tackle inequalities originating from the social determinants. The concern for inequalities, and for inequities, ‘unfair and remediable inequality’ [5], is central to WHO's mandate, harking back to the original definition of health in the WHO Constitution and in Health for All.

The SDH approach goes beyond a biomedical understanding of schistosomiasis as it affects individuals to consider the social and behavioural setting within which the infection is transmitted and has its impact. It encompasses every aspect of schistosomiasis transmission and control: diagnosis, treatment and care, preventive activities such as health education, vector control, and the provision of safe water and sanitation.

In this paper, I will present a preliminary exploration of the current challenges social determinants present to schistosomiasis research, and how these may affect plans for future research and control activities in some of the poorest countries of the world. These challenges can be explored by way of the knowledge networks WHO identified for the consideration of the Commission. They include: measurement, health systems, employment conditions, globalization, early child development, urban settings, priority public health conditions, gender and social exclusion [9,13] (for more information on SDH see CSDH 2005[a] and 2005[b] [2,3]).

For the Commission, schistosomiasis is not likely to be identified as a priority public health condition. However, some of the Commission's concerns for priority health conditions are relevant for schistosomiasis. These include the integration of SDH policies and actions into general health programmes; equitable access to public services; intersectoral action; and promoting equitable access to health care. It is essential that schistosomiasis be regarded as an equity issue, as the disease is most common among poor, marginal populations. Moreover, it is now recognized as being associated with nutritional deficiencies that are a major barrier to social development.

The changing emphasis on the social determinants of schistosomiasis

The importance of the social determinants of schistosomiasis for researchers and policy-makers is reflected in the various constituent strategies of control programmes. These have changed with the development of new tools, new (measurable) objectives, and new perspectives on what it is possible to achieve through social action and public policies. In the era before praziquantel, the social context of treatment was largely ignored in the mass treatment programmes carried out by authoritarian colonial regimes and their successors. Research on the social determinants of transmission focused on water contact behaviour. With the introduction of praziquantel as an effective treatment in the 1980s, it became important to identify social/demographic groups to be targeted for treatment through the primary health care system. Programme objectives focused on the control of transmission, prioritizing, among others, school-age children, who experienced the largest number of infections and shed the largest number of schistosomes.

Currently however, the core strategy of providing treatment with praziquantel has as its objective the control of morbidity. Risk groups have been re-defined as those vulnerable to infection and/or less likely to receive treatment through routine primary health care services. This approach echoes the emphasis in the SDH on equity and reaching those in society who are most vulnerable. Three risk groups have been identified in the literature:

Those engaging in certain occupations - especially fishing, and agricultural activities associated with irrigation.
Women - during pregnancy, and exposure during domestic activities.
Children of school age.

This change in focus occurred when research identified previously hidden morbidity due to schistosomiasis. School-age children are of particular concern, not only because of the high rates of reinfection, but mainly because of the association between schistosomiasis and stunting, vitamin A deficiency and developmental and cognitive problems. For pregnant women, deliberately omitted in earlier treatment programmes, treatment could also help to limit nutritional deficiencies which are exacerbated by schistosomiasis, especially iron deficiency anaemia.

Attention among researchers and public health specialists is now shifting to sub-Saharan Africa, where endemic countries are among the poorest in the world. Here, schistosomiasis programmes will be operating in very different social and political environments from countries such as Egypt, Morocco, Brazil, the Philippines and China, which recently claimed to have achieved successful morbidity control. These last mentioned countries are considered as being within the range of medium (rather than low) human development.

Schistosomiasis as a disease of poverty

As of 2005, 85% of all schistosomiasis infections are found in sub-Saharan Africa, mostly among poor people who live in remote areas, without access to health services, safe water, sanitation, and education. We now need to give more attention to schistosomiasis as a disease of poverty. Indeed, because of the particular dynamics of schistosomiasis transmission, and the need for treatment, it is possible to argue that the presence of schistosomiasis can be used as an indicator of poverty. What difference does this recognition of the link between poverty and schistosomiasis make to our research agenda, and to the way we present our findings to those with the power to take action?

The social determinants of schistosomiasis in sub-Saharan Africa

Among the characteristics of poor people and poor households relevant for schistosomiasis research in sub-Saharan Africa are:

Lack of access to resources, especially health services, safe water and sanitation, and education.
Poor people suffer poorer health than those who are better off. They need more health care, but often get less. The poor are defined as ‘hard to reach’: care is more expensive and difficult to deliver.
Poor people are more likely to have an inadequate diet than the better off.
Many poor areas and individuals have limited social capital, and limited access to social networks essential to obtain resources and overcome periodic domestic crises.

The result of these accumulated disadvantages is marginalization and social exclusion from the larger society. Because of this, poverty is often hidden, and its extent underestimated.

The UNDP Human Development Indicators (HDI) are generalized measures of well-being. These indicators are aggregated into a composite index and ranked for each country. Those listed in the table below are relevant for the social determinants of schistosomiasis, and give an indication of the relative standing of various countries. However, because these figures are averages, they do not identify the extent of inequality in a country, the gap between the average and those at the bottom of the heap. Intensity of infection, morbidity and disease risk are likely to be highest in the poorest sector.

Definitions:

Percentage of population without access to improved water sources: Unimproved water sources include vendors, tanker trucks, and unprotected wells and springs. Reasonable access is defined as the availability of at least 20 litres a person per day from a source within one km of the dwelling. (A central issue here is affordability, whether buying from water vendors or from newly privatized water companies.)
Percentage of the population without access to improved sanitation: Adequate excreta disposal facilities include connections to sewer or septic tank system, pour-flush latrine, simple pit latrine, or VIP latrine. Facilities are considered adequate if they are private or shared (but not public), and if they can effectively prevent human, animal and insect contact with excreta.
Under height for age: > 2 standard deviations below the median of the reference population; moderate and severe stunting (evidence of long-term nutritional deficiency).
Percentage of population living on less than US 1$ a day.
Net primary enrolment ratio: number of students enrolled as percentage of those of official school age for this level.
Percentage of births attended by skilled health personnel.

Source: UNDP, 2005, derived from tables 3, 6, 7 and 12 [19].

All countries in the Low Human Development category listed above are targeted for schistosomiasis treatment interventions. Except for Nigeria, the most populous country in Africa, they have recently been added to the list of countries covered by the Schistosomiasis Control Initiative (SCI). The poorest country, Niger, is at the bottom of the human development league, 177th of 177 countries for which records are available.

Many of these countries have inadequate health systems. It is difficult to provide meaningful figures that capture the many aspects of access to health care. The proportion of births attended by skilled health personnel has been shown to be related to child and maternal survival. This indicator can also stand as a proxy indicator for general access to health care. For these reasons it is used as a key indicator for the Millennium Development Goals. Data for these countries on skilled birth attendants also show a large discrepancy between top and bottom wealth quintiles, with at least one third fewer births attended by skilled personnel in the poorest 20% of households compared to the richest 20% [19].

Measuring the social determinants

Exploration of the social determinants of health raises a number of methodological issues, chiefly related to measurement, that are not experienced in the more quantitatively oriented discipline of epidemiology. Epidemiological studies can, often in a matter of weeks, measure the impact of treatment by comparing the levels of infection before and after treatment. But it is likely to take much longer for the impact of social determinants, be they changes in behaviour, in wealth status, or in access to water and sanitation, to show up in SDH evaluation studies. Also the methods, definitions and scale of operation used in SDH research are distinct from those used in epidemiology.

Community-based research is essential in SDH research to provide a view of schistosomiasis at the local level, in the setting in which interventions actually have an impact on health. Concern for the social determinants of schistosomiasis involves coming to an understanding not only of what local people do, but why. These ‘why’ questions illustrate ‘process’, linkages between behaviour and what local people consider is feasible and appropriate, given their knowledge, priorities and skills. Processes are difficult to measure objectively, but the dynamics of change can be analysed rigorously. Information on topics such as water use and treatment-seeking behaviour can be used for health messages and for planning improvements in access to safe water and sanitation.

In tropical Africa, detailed studies of handwashing, a critical hygiene behaviour in the prevention of diarrhoeal disease, have been carried out in rural settings with poor access to safe water and sanitation. These studies have been used to develop hygiene education and rapid assessment protocols for use at the community level. Changes in daily water use (relevant for schistosomiasis control) and handwashing have a high likelihood of being sustainable once established, as they are repeated on a daily basis; they become habitual activities that are handed down to children during socialization [4].^*

In the context of local conditions, many terms used in discussions of the social determinants of schistosomiasis take on specific significance. For example, with the recent emphasis on occupation and vulnerability to infection, survey questions need to be re-evaluated. Many survey questions focus on the major occupation. However, surveys should include a full range of work-related activities, by women and men, as these affect such things as the time available to visit health centres for treatment, and exposure to infection during farming. Poor people need to engage in a multiplicity of activities to ensure household survival. Women's activities are especially likely to be missed as they occur in the informal sector. They include preparing and selling food, looking after cattle and poultry, and working alongside their husbands in the fields. Women's domestic roles can also be seen as contributing to work-related activities, as they support household members engaged in income-generating activities. Domestic water management (collection, storage, use and disposal of water) can consume many hours a day when there is no water, or no adequate drainage for waste water within the house [11,20].

Social capital, comprising social networks used to access resources, is a vital resource for people in all societies. Horizontal networks, mostly involving kin and neighbours, help people respond to domestic crises, while vertical networks link them to those with more ‘social power’ and help them gain access to education, health care, subsidized food, etc. Although people in poor communities often have little social capital, some have good social networks, which, because they operate informally, are outside the purview of official observers who belong to a different social class. These local variations must be recognized [17].

Research implications

Researching gender

The term ‘gender’ refers to the social roles, responsibilities and activities of males and females. Gender is socially determined, while the term ‘sex’ is biologically determined; therefore it is not enough to simply replace the term ‘sex’ with the term ‘gender’ in epidemiological studies. The need to disaggregate data according to gender is well known. Aspects of gender relevant to schistosomiasis include: gendered tasks, gendered spaces, and gendered treatment-seeking behavior [11].

Current treatment strategies, which focus on vulnerable women, need to take a holistic view of the status of women, and their lack of social power, contrasted with the social and economic priority granted by the wider society to men. Pregnant and lactating women, neglected until recently in treatment programmes, need treatment for schistosomiasis and nutritional deficiencies that affect their own health and the health of their unborn children. How can such treatment reach those who need it most, and to what extent can it be combined with other programmes that involve women and their young children, such as nutritional supplements and vaccination?

Community-based studies of female genital schistosomiasis (FGS) are needed. These require gender sensitivity in working with local populations, and health staff, as the infection has symptoms that mimic sexually transmitted diseases (STDs). They also require a detailed knowledge of local gender dynamics, and reaching out to men as well as to women [18]. We need more community studies on FGS associated with S. haematobium; there are none as yet on FGS due to S. mansoni. There have been few community studies of male genital schistosomiasis [6,10].

The impact of globalization on schistosomiasis

Globalization can be briefly defined as a long-term process of increasing global connectivity and change. It is often associated with increasing poverty, as poor people are vulnerable to loss of employment (due to changing global market structures) and rights to health care (due to failing health systems, regulated by structural adjustment programmes). Globalization means, in most cases, that control of the financial affairs of a country resides beyond its borders. (See also the TDR publication on globalization and infectious diseases [16], which reviews the changes in disease distribution, transmission rate, and disease management).

Population movements are increasingly due to globalization. Non-immune populations can be exposed to infection in new areas; infected people can move to new areas taking schistosomes with them. Poor people moving to new areas often fail to escape the poverty that drove them to move in the first place. Forced population movements are associated with extreme vulnerability to disease, especially due to malnutrition and the absence of safe water and sanitation. Sub-Saharan Africa has the largest number of refugees of any world region, around 2 700 000. The data on those who have been internally displaced are less reliable, but suggest far larger numbers, overall, than those officially recognized as refugees [19].

Researchers need to update the earlier assessments of how water resources development affects the status of schistosomiasis [7]. The ecological and social disruptions caused by large dams are now better understood than they were ten years ago. Current concern about the Three Gorges Dam on the Yangtze River in China appears to focus on ecological change (the movement of vector snails), but construction also involves a vast forced and voluntary movement of millions of people, carrying with them their diseases, culture and behaviour. Is it still sufficient to call for intersectoral collaboration in planning and in disease impact assessment? What role, if any, do international agencies, donors and other interested parties have in protecting the health of people affected by such projects?

Urbanization is also an aspect of globalization, with the push/pull pressures of rural poverty and urban opportunity resulting in movement to towns. Many impoverished people move to shanty towns on the peri-urban fringes of large population centres, where infrastructure for health, water and sanitation has not yet been established. Assumptions that schistosomiasis is a rural disease need to be revised because:

Rural people bring their diseases with them to the rapidly expanding population centres.
Unsafe sanitation and water supplies, plus unchanged behaviour, will facilitate the establishment of disease transmission in urban slums.
Migration and globalization have broken down established ideas of what constitutes ‘rural’ and ‘urban’. These definitions are not consistent from country to country. Definitions reflect past cultural and social realities, and administrative convenience. In the Nile delta, water and sanitation conditions in villages with a population of 10 000 or more may be similar to those in poor urban areas. In Brazil, metropolitan regions are defined as urban but appear to include small scattered settlements in which conditions are very similar to those in rural areas.

Governance is a globalization issue, as today, more than ever before, many decisions made by a government are limited, or controlled, by international institutions, multinational businesses and regulatory frameworks; some have a positive impact, many are negative. Governance can be defined as ‘a set of traditions and institutions by which authority in a country is exercised’. The main areas of concern for governance are: voice and accountability, political stability, government effectiveness, the rule of law and corruption [12]. Corruption is facilitated as corrupt local nationals take advantage of international financial facilities to siphon off vast sums of money that could have been used for social programmes. Indicators of good governance are subjective, and depend on the preconceptions and objectives of those making the assessments. They can provide a general indication of the extent to which governments can provide services to their people that are affordable and equitably distributed. They are often used by donor agencies to determine whether debt can be forgiven, and if aid should be provided, and if so, how much. Especially in poor countries that are heavily aid dependent, coordination by donors at the national level now strongly supports intersectoral planning. This offers intriguing new possibilities for health ministries to think outside their usual parameters, and for disease control programmes to become more closely integrated with other health initiatives.

Within ministries of health, health sector reform (HSR) is heavily influenced (and financed) by international organizations and donors. It is directed primarily at streamlining management, upgrading facilities and training health personnel. Its involvement in actual health interventions is limited to the effective delivery of a package of essential services. Relevant essential services for an endemic area may include schistosomiasis surveillance and treatment. HSR planners pay lip service to equity in access to health care. However, in practice, HSR policies, focusing on management-related issues and cost effectiveness, do not leave much room for equity considerations. Even among uniformly poor populations, the very poor may not be reached [1].

Children of school age

A major SDH knowledge area is early child development. However, many health problems faced by older, school-age children are similar to those of younger children. They are also rooted in social determinants such as poverty, malnutrition, and poor hygiene that are linked to the lack of safe water and sanitation. New research approaches are needed on the nutritional vulnerability of school-age children who suffer from schistosomiasis and other intestinal parasites.

In poor endemic countries in sub-Saharan Africa, up to one-third of the children under five may be stunted, indicating long-term nutritional deficiency. Most attention focuses on growth deficit among young children but it is likely to continue as polyparasitism, which impedes the absorption of nutrients, and children face added nutrient demands during puberty. Studies among older children have found a correlation between schistosomiasis and childhood stunting. Assis et al. (2004) pioneered a new approach by including food intake when looking at nutritional status and S. mansoni infection in the poor north-eastern Brazilian state of Bahia. They found that children aged 7–14 who were heavily infected or had an inadequate intake of lipids (fats) were at higher risk of stunting than non-infected children.

This research suggests possibilities for further exploration of the link between inadequate nutritional intake and schistosomiasis, drawing on findings in local settings, and incorporating considerations of local dietary preferences and food availability and affordability. Such research could also strengthen the argument for delivering schistosomiasis treatment alongside treatments for other locally endemic diseases, and nutritional supplements. This would be cost effective, as treatment would target the same groups.

More research is needed on locally appropriate strategies to treat out-of-school children as less than half of the children in endemic countries in Africa may be enrolled in school. While many children withdraw or attend school irregularly because they are needed to work or live far from school, only a small proportion will attend regularly enough to be covered in school-based programmes. However, out-of-school children are more likely to be at risk of infection. A study in a poor rural area of Egypt found that out-of-school children, especially girls, had far higher rates of infection than did those in school. The research team designed a protocol for reaching these children within the existing school-based framework [8].

In poor countries in Africa, the deworming programme supported by Partnership for Child Development (which includes treatment for schistosomiasis) is being delivered through schools, on the grounds that schools are more ubiquitous than health centres, and that teachers can be trained to give out the drugs. Little research appears to have been done on delivering treatment to out-of-school children in these countries through the school system. Given the focus on school-age children, and the proven role of education in fostering social development and health, such health programmes could form part of an overall strategy to encourage school attendance by children from poor families by providing free meals, health care and small payments to children who attended regularly. If a school system is not deemed suitable for the delivery of such programmes, alternative strategies for reaching school-age children could be modelled on community-based strategies such as those used in Uganda to deliver treatment for schistosomiasis, onchocerciasis and intestinal helminths, and in Nigeria for schistosomiasis, lymphatic filariasis and onchocerciasis [14]

The challenge of new strategies and competing health priorities

Today schistosomiasis control has moved away from its earlier focus on integrated projects incorporating specific schistosomiasis-related interventions such as diagnosis, treatment, health education, vector control, and coordination with programmes to provide safe water and sanitation. At the present time, schistosomiasis is more often seen as an element in broader programmes that combine schistosomiasis control with other health interventions. At the same time the distinction between top-down vertical disease-specific programmes and local-level horizontal programmes may no longer be relevant. The new emphasis is on intersectoral programmes and other activities encouraged (or dictated) by new globalizing forces, including multinational companies and international health programmes. Schistosomiasis programmes should now be identified as networks: a web of relationships that links organizations and individuals across organizations [15].

The health priorities of poor countries in sub-Saharan Africa, especially those being devastated by the HIV/AIDS epidemic, also need to be recognized by researchers. Providing basic health care in low income countries costs around US$ 30–40 per capita, yet most poor countries spend less than US$ 6 per capita on health [19]. People living on less than US$ 1 a day cannot be expected to pay for health care. In such a context, the concept of cost recovery is a non-starter that can only succeed in shutting out the poor from health care. Just over one-third of the people in sub-Saharan Africa live in countries that have experienced a decline in HDI since 1990 because of the combined impact of HIV/AIDS and structural adjustment policies [19]. Even if current attempts to relieve debt use the money to restructure health and education, the challenge for the poorest countries to provide effective and sustainable schistosomiasis control is formidable. Where should schistosomiasis research position itself in this new context?

Conclusions: new directions for research on the social determinants of health

Research on the social determinants of schistosomiasis is now focusing on the poorest populations in sub-Saharan Africa, where governments and households have very limited resources. The poorest people, those least likely to be able to pay for health care even if it is provided nearby, are those most likely to be at risk from schistosomiasis. A research agenda needs to incorporate the following specific areas of research that reflect the current realities in poor countries in sub-Saharan Africa:

The impact of population movements on schistosomiasis control.
A new look at gender and schistosomiasis: women's vulnerability; pregnant women; female (and male) schistosomiasis; the structural underpinnings of women's low status that result in their marginalization in the control programmes of various countries and localities.
Strategies for reaching school-age children that take account of local conditions, feasibility, sustainability.
The role of urbanization, including the extent to which schistosomiasis is an urban or rural problem, and whether these terms are still relevant.

Some of these conclusions are not specific to schistosomiasis. They are the unavoidable consequence of linking the disease to poverty, and of looking at the situation from a vantage point largely outside schistosomiasis research. Within this framework, equity becomes a central issue. Technical topics, such as the social aspects of diagnostics and morbidity measurement, may appear less important but they, too, can be filtered through the lens of equity. In terms of schistosomiasis research and methodology, an approach to schistosomiasis via its social determinants requires some new definition for once standard concepts, and a methodology for appropriate locally oriented research.

Footnotes

*. see also http://www.lshtm.ac.uk/dcvbu/staff/valspage.htm , accessed 5/15/2004.

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