ABSTRACT
The article aims to estimate the burden of disease attributable to unsafe water, sanitation and hygiene (WSH) by sex and age groups in Vietnam in 2008. The WHO comparative risk assessment methodology was applied in the study. The results showed that 2,785 deaths were attributable to unsafe WSH accounting for 0.51% of total deaths in Vietnam in 2008. Among these deaths caused by diarrhea, 7.5% (N = 209) were children under 5 years old, contributing 1.09% to the total deaths in this age group. Overall, the burden due to unsafe WSH was equivalent to 0.37%
of the total disease burden for Vietnam (measured by disability-adjusted life years – DALYs) that ranked this risk factor number ten in the country. In conclusion, unsafe WSH is an important risk factor of diseases in Vietnam. High priority needs to be given to the provision of safety and sustainable sanitation and water facilities as well as to promoting safe hygiene behaviors, particularly among children.
Key words: Unsafe water sanitation and hygiene, comparative risk assessment in Vietnam, DALYs attributable for WSH, risk factor, Diarrhea
Estimating the burden of disease
attributable to unsafe water and lack of sanitation and hygiene in Vietnam in 2008
Tran Khanh Long1, Nguyen Trang Nhung1, Bui Ngoc Linh1, Nguyen Thanh Huong1
1 Hanoi School of Public Health – 138 Giang Vo, Ba Dinh, Hanoi, 10000 Coresponding Author:
Tran Khanh Long, Hanoi School of Public Health – 138 Giang Vo, Ba Dinh, Hanoi, 10000. Email: [email protected]
INTRODUCTION
Diarrhea ranks the second leading cause of death among children under five years old, which accounted for 1 out of 9 deaths regarding child mortality rate worldwide1. Dehydration resulting from diarrhea causes approximately 1.8 million deaths every year and 72.8 million disability- adjusted life years (DALYs) annually2. In Vietnam diarrhea was the seventh leading cause of DALYs among children below 15 years of age in both males and females, and it accounted for 1% of total DALYs in Vietnam in 2008. Among children under five years old, diarrhea is the sixth leading cause of deaths (3.6% of the overall total number of deaths)3.
Unsafe water, lack of sanitation and hygiene (WSH) is a key risk factor for diarrhea and other diseases. Globally, about 1.5 million deaths per year from diarrhea are attributed to environmental factors, essentially water, sanitation and hygiene. The problem is more severe in middle and low-income countries. The World Health Organization (WHO) reported that unsafe WSH has been estimated to cause 6.1% of all deaths and around 4.3% of all DALYs in low- income countries4.
In Vietnam, lack of water and sanitation works along with low awareness, inappropriate hygiene behaviors and habits in many places have negative impacts on community's health. An estimate of average amount of water use in urban areas is 80-90 litter/person/day which is lower than the amount of water use in large cities (120-130 litter/person/day5)6. The rate of rural people having access to domestic water meeting Vietnamese standard QCVN 02:2009/BYT is 40%7. In addition, According to a study named“The relation between sanitation, household water source and mothers' behavior of looking after children with nutritional status of children under 5 in Vietnam2010”conducted by Vietnam Health Environment Management Agency and UNICEF in 2010, 15.1% of households used water from rivers, springs, ponds and lakes as the main source for drinking and domestic purposes. 30.4% of households have unsanitary water source. 4.6%
and 15.3% of water sources have high and very high risks of pollution, respectively8.
In terms of sanitation, a survey on rural sanitation conducted by Vietnam Ministry of Health in 2007 demonstrated that the rate of rural household latrine meeting sanitation standards based on the Decision No 08/2005/QĐ-BYT was especially low. Only 18% of rural households have latrines meeting sanitation standards in construction, use and maintenance. By considering standards in construction only, 22.5% of rural households in Vietnam have latrines meeting the standards. In terms of sanitation standards in use and maintenance, only 22.2% of rural households have qualified latrines. The survey also reported that 75% of rural households have latrines, but only 33% of them have sanitary latrines9.
Water and sanitation are the millennium development goals that Vietnamese government has already committed and this sector always plays an important role in the aspect of socio-economic in Vietnam. Therefore, scientific data on WSH is a requirement in Vietnam’s situation. The aims of this article is to quantify the burden of disease in terms of death and DALYs regarding unsafe water, low sanitation and hygiene by sex and age groups in Vietnam in 2008.
METHODS
Comparative risk assessment methodology developed by WHO was used to estimate the disease burden attributable to unsafe WSH10. The composite risk factor was defined as “multiple factors”, namely the ingestion of unsafe water, lack of water due to inadequate hygiene, poor personal and domestic hygiene and agricultural practices. This contacted with unsafe water, and inadequate development and management of water resources or water systems10. We attributed only diarrheal disease to this risk factor for Vietnam as there is no burden of disease estimated for ‘intestinal parasites’ and schistosomiasis.
Customized MS Excel spreadsheets based on templates used in the Australian and South African studies11 were applied to calculate the attributable burden. As unsafe WSH is a risk factor with discrete exposure categories, the population attributable fraction (PAF) was used. PAFs were calculated using the following formula:
Where pi is the prevalence of exposure level i, RRi is the RR of disease in exposure level i, and k is the total number of exposures.
PAFs were then applied to Vietnam burden of disease estimated for deaths, premature mortality or years of life lost (YLL), years lived with disability (YLD), and disability-adjusted life years (DALYs) of diarhea to calculate attributable burden in 2008.
Monte Carlo simulation-modeling techniques were used to present uncertainty ranges around point estimates that reflect all the main sources of uncertainty in the calculations. Ersatz software Table 1. Scenarios for estimating exposure for diarrhoeal diseases
Source: Global CRA10
version 1.012 was used as an add-in to Excel, allowing multiple recalculations of the Excel spreadsheet, each time a value is randomly drawn from the defined distribution as input variables choosing a randomly drawn value from the distributions defined for input variables.
A scenario-based approach was applied to quantify the risk of diarrheal disease using exposure or combination of risk factors. Scenarios were defined on the basis of the type of water and sanitation infrastructure (Table 1). Scenario I represents the minimum theoretical risk and Scenario II is the situation typically encountered in developed countries. These two scenarios have a low to medium load of fecal-oral pathogens in the environment, characterized by more than 98% coverage in improved water supply and sanitation and a regional incidence of diarrhea of less than 0.3 per person per year13. Scenarios IV-VI are in a high faecal-oral pathogen environment, typically in developing countries, and are characterized by their access to water and sanitation infrastructure. Scenario III represents any intervention that improves on Scenario IV, and does not occur widely at the moment. As such, various transitions can be proposed for scenario III, and it presents a cluster of possibilities rather than a specific scenario.
Risk estimates assigned to each exposure scenario were based on those of Prüss et al10who used large surveys and reviews of multi-country studies to derive risk averages – the average risk related to the described scenarios across the world and in an array of situations. The ideal situation (scenario I) was assigned to a relative risk (RR) of 1.0. No difference in relative risk across age groups or between sexes was assumed (Table 2).
Data on prevalence and population distribution of exposure were obtained from Vietnam Household Living Standard Survey14 which reported the main source of water supply and toilet facilities available to households. Based on these data, households were divided into 3 categories:
poor, intermediate, and good access to water supply and sanitation facilities (Table 3).
These 3x3 groups were then matched as closely as possible to the exposure scenarios
RESULTS
Table 4 shows the situation of water, sanitation and hygiene in Vietnam in 2008. There were only Table 2. Relative risk estimates associated with exposure scenarios and distribution of the
population between exposure scenarios
Source: Prüss-Üstün et al10
21.7% of households having good quality of water use and 36.7% of households having good status of hygiene and sanitation. In total, only 16% of the population has good toilets and using sanitation water.
Table 5 shows PAF and burden of unsafe WSH in Vietnam in 2008. It was estimated that 0.51%
of all deaths in Vietnam due to unsafe WSH, which were equivalent to 2,785 deaths. Among these deaths caused by diarrhea, 7.5% (N= 209) were children under 5 years old, contributing 1.09%
to the total deaths in this age group. The total burden of the disease due to this risk factor in 2008 was 45,267 DALYs, 51.2% and 48.8% of which was attributed for female and male, respectively.
Table 3. Water and hygiene definition table
Table 4. Prevalence of water and sanitation of Vietnam 2008
The DALYs attributable to unsafe WSH were equivalent to 0.37% (Table 5) of the total disease burden in Vietnam. Unsafe WSH was responsible for 1.28% of total burden of diseases in children under five years old. In other words, it was responsible for 11,106 DALYs in this age group category.
DISCUSSION
In Vietnam, unsafe WSH is the tenth risk factor analyzed in the country and is the main risk factor burden of diseases for children under 5 years of age in Vietnam (e.g., 1.09% of total deaths and 1.28% of total burden diseases). Therefore, unsafe WSH is considerably more important to the group of under 5- year old than to the whole population. Although in Vietnam the proportion of all attributable deaths and DALYs in the age group 0 - 4 years is less than that of global estimates for this age group, the study results are consistent with those reported in the global unsafe WSH risk factor assessment. This study applied the approach that allocates the Vietnam population to different exposure scenarios in order to determine various risks of diarrheal diseases from unsafe WSH. The allocation of unsafe WSH categories proposed in the study is different from the distribution as in the WHO Western Pacific sub-region (WPR-B) which includes Vietnam, where 0% was allocated to scenario II, 42% to scenario IV, 1%, 33% and 24% to scenarios Va, Vb and VI respectively15. However, we believe that the allocation described here reasonably reflects Vietnam situation.
This study has a number of limitations. First, the article did not look at the joint effects of risk factors such as unsafe WSH and malnutrition or underweight. The burden of diarrheal diseases reported as being attributable to unsafe WSH may therefore underestimate the true attributable fraction. A recent evaluation suggests that approximately 50% of the disease burden of malnutrition can be attributed to unsafe WSH, highlighting the complexity of these effects16. The second limitation of the study is the lack of data on others unsafe WSH related diseases such Table 5. Population attributable fractions (PAF) and burden of unsafe water, sanitation
and hygiene, Vietnam 2008
as schistosomiasis, trachoma, ascariasis, trichuriasis or Hookworm disease15. Diarrhea disease is well-known the principle disease to estimate the attributable fraction of unsafe WSH. However, the inadequacy of these data may cause an under-estimate of the true attributable fraction of unsafe WSH risk factor.
Finally, it is not possible within this assessment to examine how the burden is distributed between rural and urban setting, and between poor and wealthy households. However, RRs associated with different exposure scenarios clearly indicate that households with poorer access to water and sanitation facilities are at substantially greater risk of developing diarrhea and other diseases.
Since most of these households are likely to be located in rural areas, it is valid to assume that poor households are the most vulnerable to the burden of unsafe water sanitation and hygiene.
Others research on water access in relation to the recent cholera epidemic and water related diseases also support this assumption6,9,17.
RECOMMENDATION
Improving access to safe and sustainable sanitation and water facilities, particularly in poorly served urban and rural communities should be highly prioritized. The high burden of diseases attributed to unsafe WSH, especially in children, provides a strong public health justification for the recommendation.
Particular attention is urgently needed in terms of children's hygiene behaviors within their homes and childcare facilities. Water and sanitation infrastructure programs should include a strong hygiene behavior component to ensure that maximum health benefits are realized.
Immediate and appropriate treatment of diarrheal disease also needs to be promoted.
Finally, it is essential to have more research on diseases related to unsafe WSH in Vietnam such as schistosomiasis, trachoma, ascariasis, trichuriasis and Hookworm disease, so that we could have a more comprehensive data to evaluate the burden of diseases attributed to unsafe WSH in Vietnam.
DECLARATION OF CONFLICTING INTERESTS
The authors declared no potential conflicts of interest with respect to the research, authorship and publication of this article.
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