Background
Worldwide, 18% of all deaths in children under five are due to diarrheal diseases, accounting for approximately 1.4 million deaths per year. This makes diarrheal diseases a leading cause of child death globally[
1,
2]. The most common cause of diarrheal diseases results from gastrointestinal infections[
3,
4]. The majority of diarrheal deaths in children are due to the loss of large quantities of water and electrolytes (sodium, chloride and potassium) through liquid stool, resulting in severe dehydration and acidosis[
5].
Since diarrheal diseases are primarily spread through the faecal-oral route, preventive measures include improving access to safe drinking water and adequate sanitation. Wealthy nations and international bodies first began designating assistance for water and sanitation specifically through the World Bank in 1961 [
6]. The history of development assistance in the water and sanitation sector, summarized by Grover and others, includes investment in service provision and infrastructure, and is marked by numerous international conferences and declarations, multilateral organizational involvement, the International Drinking Water Supply and Sanitation Decade (1990s), and the creation of water working groups, councils, and partnerships [
6‐
11]. In 2000, the Millennium Development Goals (MDGs), were developed as a way to draw attention to global health and social justice issues and measure global progress on these goals. Target four under Goal 7 is to "halve, by 2015, the proportion of the population without sustainable access to safe drinking water and basic sanitation"[
12]. Goal 4 is to "Reduce by two-thirds, the under-five mortality rate". The adoption of the MDGs may in part explain the increase in overseas development assistance (ODA) to over 5 times that of 1990 levels[
13].
Studies on aid effectiveness have been mixed. Most have dealt with the relationship between ODA and economic growth[
14‐
16] the effect of predictability[
17] and aid modality[
18,
19] on development. More recently some have examined the effectiveness of foreign aid in poverty reduction and human development [
20‐
22]. Only one study has looked at aid effectiveness and population access to water and sanitation, though as part of a framework examining public service delivery in general [
23]. Our aim was to specifically examine the relationship between per capita ODA designated to the water and sanitation, the change in population access to improved water and sanitation services, and subsequent indicators of child health.
Discussion
Water and sanitation infrastructure substantially alters childhood mortality and morbidity [
29]. However, the association between country level ODA and mortality has not been investigated. We have demonstrated that countries receiving the most WSS-ODA were 4-18 times more likely than countries in the lowest tertile of assistance to achieve greater gains in population access to improved water supply. We were unable to demonstrate consistent improvements in access to sanitation. Those countries with greatest gains in sanitation were 8-9 times more likely to have greater reductions in infant and child mortality.
Comparing the highest tertiles of WSS-ODA from 2002 to 2006, all of the adjusted odds ratios achieving change in the top two tertiles of change in population access to water were statistically significant and ranged from 4.41 times (1.01-19.26) in 2003 to 18.15 times (3.46-95.21) in 2004 more likely than the countries in the lowest tertile of WSS-ODA per capita. In general, countries falling in the highest tertile of per capita WSS-ODA are most likely to experience an increase in the relative percent of the population with access to improved water sources. For all years but 2004 and 2006, the countries falling within the middle tertile of WSS-ODA did not experience significantly higher odds of increasing population access to water than those in the lowest tertile. We propose this could be due to a lack of statistical power, or because of increasing population sizes, where WSS-ODA levels that fall below a certain threshold do not appear to increase access to coverage of water and sanitation services because the population is growing faster than additional services are being provided.
Despite trends of improved access to sanitation, most evaluations were statistically non-significant. It is unclear whether or not the lack of association is due to a true lack of association between WSS-ODA and sanitation, or whether or not, because of the higher complexity of sanitation systems, there is a lag period for the association to emerge. It may seem a paradox that overall, smaller relative gains were made in access to water compared to access to sanitation, yet WSS-ODA was only significantly related to the change in water access. A large factor in explaining this paradox is that the median baseline value for water access was much higher compared to that of sanitation (59% vs. 28%). Sanitation appears in some ways to be at odds with ODA and government health expenditures, as negative correlations were observed for both the sum of the total ODA per capita between 2002 and 2006 (-0.30, p = 0.041) and per capita government health expenditures in 2006 (-0.33, p = 0.025). Further analysis is required to explain the relationship between ODA and sanitation.
Interestingly, there was no significant correlation between total ODA per capita received by a country and any of the child health indicators. There was however a significant association between higher levels of increase in sanitation and reductions in infant and child mortality, with adjusted odds ratios of 8 and 9 times for the highest compared to the lowest tertiles, respectively. It is unknown why there is an apparent lack of association between this relationship and WSS-ODA. It may be due to ineffectiveness in investments, a weak capacity of the mandated national institutions, or perhaps due to success on behalf of local, non-internationally funded efforts. The higher odds of sanitation, as compared to water access, producing significant reductions in child mortality is consistent with the literature including a study by Fewtrell and co-workers [
29‐
31], who showed that sanitation and hygiene have a greater impact in relative risk of acquiring diarrhea compared to water quality and water supply projects. And yet, at least for donors that do provide disaggregated WSS-ODA data, only 30% of funding goes to sanitation and hygiene efforts [
32]. This highlights the need for decision-makers to be more intentional with allocating WSS-ODA towards sanitation projects.
While public health practitioners may consider water and sanitation to go hand in hand, this natural association must not be assumed in all cultural contexts [
31]. Water, for example, is often interpreted as a broad community issue that contributes to the local economies in a variety of important ways, including employment based on clean water access, such as food sales. Sanitation, on the other hand, may be associated with cultural taboos, preventing local discussion of this important child health indicator [
32]. Thus interventions must recognize the uniqueness in approach necessary to optimize maximum health benefits from water supply and sanitation and hygiene projects. Indeed, on an international level, sanitation is gaining more unique attention, as evidenced by the declaration by the United Nations of 2008 as the International Year of Sanitation. Similarly, the eThekwini Declaration was supported by 32 African ministers responsible for sanitation to ensure increased spending on sanitation [
33]. The impact of these assurances need to be monitored. Currently the EU Water Initiative is working to provide a feasible strategy to disaggregate WSS-ODA data into aid for water supply, sanitation and hygiene, and water resources management [
32]. When this data becomes available, a more thorough analysis of the relationship between water and sanitation-designated funding, and their respective impacts on health should be assessed.
As with any study, this research was bound by certain limitations. First, due to the nature of the research question dealing with only low-income countries, our sample size was relatively small, which constrained some steps in our statistical analysis. It was further constrained for analysis of health outcomes by the fact that diarrhoeal diseases account for an estimated 18% of child deaths [
1]. Hence it is possible that with a larger number of countries, correlations and odds ratios of borderline significance would become significant.
Another limitation is that ecological studies are always to be interpreted with the understanding that cross-country comparisons cannot capture fully all of the unique socio-political, economic, cultural, and geographic factors that influence aid effectiveness in expanding water and sanitation infrastructure, and gains in child health made can be masked by other factors, such as increasing mortality from HIV/AIDS. Because of the scope of our research, we were unable to include an analysis of how conditions in conflict settings influence both ODA and its distribution and timeliness in expanding access to water and improved sanitation facilities. This is an important topic for future study.
As we approach 2015 and the world continues to labour to meet its commitment to the Millennium Development Goals, regular assessments should be carried out on the goals and their components. This study draws attention to the need for more research around ODA effectiveness in the expansion and maintenance of water and sanitation infrastructure. Despite the transfer of large amounts of ODA, many of the MDG targets are not expected to be met [
13,
23]. The G-8 summit in 2005 resulted in a commitment to double aid to Africa to help change the course of these projects, particularly in improving the delivery of government services and the building infrastructure for health, education, and water and sanitation [
23]. Yet Thiele and colleagues found that proportions of total aid going to water and sanitation have decreased since the early 1990s, with the proportion designated to water and sanitation dropping from 4.9% to 3.9% and 1.1% to 0.8% in 2002-2004, respectively [
34].
More research is needed to understand the seemingly paradoxical relationship between ODA and sanitation, how debt relief compares to grants and loans in proliferating water and sanitation infrastructure, what degree of public-private mixing in ownership and service provision is optimal for rapid expansion in certain resource-poor settings, and how public education can be used to compliment infrastructural expansion to produce synergistic benefits to child health. It would also be interesting to conduct an analysis determine the effectiveness of national allocations towards the water and sanitation sector.
Preparation for this study uncovered the absence of important data. To begin, our initial aim was to use diarrheal-specific mortality rates as our health outcome, since it is expected to have a stronger association with water and sanitation infrastructure than overall infant and child mortality rates. This indicator could not be employed since the percentage of deaths from diarrheal disease, as reported by the World Health Organization, was only reported for the year 2000. In addition to diarrheal mortality, we had desired to control for conflict, but could not because we were unable to find an appropriate conflict index scale.
Future research would benefit from the accessibility of sub-national level monitoring of progress in water and sanitation access as well as health surveillance. Since country-level data is often derived from census data, it is highly likely for many countries that district and even city-level data is available, but not accessible. We would strongly suggest that an international body, such as the UNICEF or the World Health Organization, solicit and make publicly available sub-national data, to help researchers avoid the ecological fallacy and be able to conduct precise and detailed inquiries.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
EP, MJB, MJ, and EM conceptualized the research question and developed the inclusion criteria, EP, MJB collected data on the variables. MJ, RB and MJB conceptualized and performed the statistical analysis. EP and MJB prepared the first draft of the manuscript. EP, MJB, MJ, EM, BJ and RB critiqued the draft, added text, and gave valuable input to refinement of the statistical analysis. Subsequent revisions were made by all authors. All authors reviewed the final draft and approved it for submission.