Sanitation in Developing Countries

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SANITATION IN DEVELOPING COUNTRIES

In 1999 the United Nations acknowledged that the development gap between rich and poor countries was widening: about three-fifths of the world's population lacked access to basic sanitation; and one-third did not have access to safe drinking water. Industrial development affects public health both favorably and unfavorably. Improved housing and social conditions and reductions in infectious diseases like gastroenteritis or pneumonia are often accompanied by increases in degenerative, noninfectious diseases like cancer and heart disease. In rapidly developing countries, such as Mexico, the People's Republic of China, and the Philippines, new public health problems often emerge before the old ones have been solved, and it is important to assess which problems pose the greatest risks to health, and which solutions are most cost-effective. Large funding organizations like the United Nations, the World Bank, and regional development banks now recognize that to solve priority health problems requires improvements in behaviors, attitudes, skills, services, products, and infrastructure that together yield lasting benefits long after external support is withdrawn.

In this global context, providing both safe drinking water and wastewater sanitation have long been recognized as priorities for the improvement of human health, especially in the prevention of infant and child mortality from diarrheas and dysenteries (e.g., Amoebiasis, caused by a protozoan; or E. coli diarrhea, caused by a bacterium). An estimated 4 billion cases of diarrheal disease occur worldwide every year, killing an estimated 3

Table 1

Major Water-Related Diseases and Sanitation Solutions
Disease	Infection route	Range	Cases ¹	Deaths per year	Problem → Sanitation Solution
Major Water-borne Diseases
1. Amoebic dysentry	Protozoa (e.g. Giardiaor Cryptosporidium ) follow the fecaloral route; i.e., feces contaminate water and/or food that is ingested.	Worldwide	500 million per year	included in 3. below	Unsanitary excreta disposal, poor personal and domestic hygiene, unsafe drinking water. → Low-cost sanitation such as latrines, pour-flush toilets, and septic tanks. Education to promote basic hygiene (e.g., washing food, handwashing before eating and preparing meals). Provide safe drinking water sources.
2. Bacillary dysentry	Bacteria by fecal-oral route	Worldwide	included in 3.	included in 3.
3. Diarrheal disease (incl. Amoebic and Bacillary dysentry)	Various bacteria, viruses, and protozoa by fecal-oral route.	Worldwide	4 billion in 1998	3-4 million
4. Cholera	Bacteria by fecal-oral route.	S. America, Africa, Asia	384,000 per year	20,000
5. Hepatitis A	Virus by fecal-oral route.	Worldwide	600,000 to 3 million per year	2,400-12,000
6. Paratyphoid & Typhoid	Bacteria by fecal-oral route.	Asia (80%), Africa, Latin America (20%)	16 million in 1996	600,000
7. Polio	Virus by fecal-oral route.	India (66%), Near East, Asia, Africa (34%)	82,000 in 1996	9,000
Major Water-based Diseases
8. Ascariasis	Eggs in human feces–larvae develop in soil–soil on food–food eaten by humans and worm infects small intestine.	Africa, Asia, Latin America	250 million in 1996	60,000	Unsanitary excreta disposal, poor personal and domestic hygiene. → Low-cost sanitation. Education to promote basic hygiene, especially in children.
9. Clonorchiasis	Worms in snails–snails eaten by fish–raw/undercooked fish eaten by humans.	Southeast Asia	28 million in 1994	None reported	Unsanitary excreta disposal, poor personal and domestic hygiene → Low-cost sanitation. Education to promote basic hygiene.
10. Dracunculiasis (Guinea worm)	Human host has blister, immersion in water causes larvae to release, larvae eaten by crustacean, in turn eaten by humans.	Sudan (78%), sub-Saharan Africa	153,000 per year	None reported	Unsafe drinking water supply. → Provide safe drinking water supply.
11. Necatoriasis (Hookworm)	Eggs in feces hatch to larvae in soil and on grass, pass into humans through skin to infect small intestine.	Tropical and subtropical Africa and Asia	900 million in 1990	60,000 per year	Unsanitary excreta disposal, poor personal and domestic hygiene. → Low-cost sanitation such as
12. Paragonimiasis	Worms in human lungs lay eggs, coughed up and swallowed–eggs excreted in feces and break in freshwater. Larvae find snail host then move into crab or crayfish–humans eat raw seafood–worms move from stomach to lungs.	Far East, Latin America	5 million in 1994	None reported	latrines, pour-flush toilets, and septic tanks. Education to promote basic hygiene.
13. Schistosomiasis (Bilharzia)	Eggs passed out in feces to water, releasing parasites–pass into snail host to replicate–pass into water–pass through human skin and become worms.	Africa, Near East, Western Pacific, Southeast Asia	200 million in 1996	20,000	Unsanitary excreta disposal, unsafe bathing water. → Provide safe water. Low-cost sanitation such as latrines, pour-flush toilets, and septic tanks.
[CONTINUED]

Table 1 continued

Major Water-Related Diseases and Sanitation Solutions
Disease	Infection route	Range	Cases ¹	Deaths per year	Problem → Sanitation Solution
*cases given as number per year (incidence) or as number of cases in existence at a given time/in a given year (prevalence)
sources: Hinrichsen et al., 1998; World Health Organization at http://www.who.ch/
Major Water-related Vector Diseases
14. Dengue	Virus passes to mosquito from infected person or animal–replicates and passes again into human by mosquito bite.	Tropical areas, Asia, Central and South America	50-100 million per year	24,000	Poor water management: poor operation of water sources, drainage and storage. Poor solid waste management. → Combination of improved water management (drainage, preventing stagnant water bodies), physical barriers to hosts (bednets, screens at night), biological methods (introduce natural enemies of hosts), and chemical (pesticides). Best methods emphasize sanitation to reduce dependence on chemicals like DDT.
15. Filariasis (includes Elephantiasis)	Worm larvae pass to mosquito and replicate–pass into humans by bite.	Africa, Eastern Mediterranean, Asia, South America	120 million in 1996	None reported
16. Malaria	Protozoa in mosquito gut pass to humans by bite.	Africa, Southeast Asia, India, South America	300-500 million per year (clinical)	2 million
17. Onchocerciasis (river blindness)	Worm embryos eaten by black flies and become larvae–pass to humans by bite.	sub-Saharan Africa, Latin America	18 million in 1996	None reported but 270,000 cases of blindness per year
18. Rift valley fever (RVF)	Virus passes to mosquito/other blood-sucking insects from infected person or animal–replicates and passes again into human by bite.	sub-Saharan Africa	No data	No data
Water-washed Diseases
19. Trachoma	Virus infects eye and infection is contagious.	Worldwide	150 million	None reported but 5.9 million cases of blindness or severe complications per year	Lack of face washing, bathing and safe water. → Provide safe water. Personal hygiene and education.
20. Flea, mite (e.g. Scabies), lice, and tick-borne diseases	Contagious skin infections caused by contact with fleas, mites, lice and ticks.	Worldwide	No data	No data

to 4 million people per year, most of them children (see Table 1). While it can be readily argued that a safe water supply plus wastewater sanitation is the most cost-effective public health goal for any given population, in practice, many social, cultural, technical, and economic factors govern whether the design and implementation of these systems will provide the long-term benefits sought.

To measure development and health progress, public health agencies use indicators such as access to water supply, access to sanitation, the under-five-year-old child mortality rate (U5MR), and per capita income. In 2000, the UN reported that the U5MR varied from 4 per 1,000 live births for developed countries like Sweden, Japan, and Norway, to 280,292, and 316 per 1,000 for Niger, Angola, and Sierra Leone, respectively. Figure 1 shows the relationship between the U5MR and access to safe water. Figure 2 shows the relationship between the U5MR and access to sanitation. These figures clearly show that improved water supply and/or sanitation can reduce child mortality (see Table 2).

WATER AND HEALTH

The uncontrolled pollution of water supplies by chemical and pathogens is one of the most serious threats to public health and the natural environment in developing countries. Standing water is a

Figure 1

medium for vector-borne diseases, and caused by poor water management, especially poor drainage. Table 1 shows the main water-related diseases from pathogens (viruses, bacteria, and protozoa), their relative geographical extent, numbers of cases, mortality rate, and sanitation solutions. Although the focus for remediation varies by disease and local conditions, all solutions include attention to four basic factors: 1) basic infrastructure (water supply and waste disposal); 2) personal and domestic hygiene; 3) better housing; and 4) primary health care and health promotion. Where basic infrastructure is lacking, pathogens are the priority contaminants, although the comparative risks posed by chemical pollutants should also be considered, especially in industrial areas and areas using pesticides. In dealing with pathogens in these areas, it is important to consider the life cycle of pathogens, pathogen infection routes, and pathogen susceptibility to treatment.

Chemical pollution of water from agricultural and/or industrial practices may include organic substances such as polychlorinated biphenyls (PCBs), chlorinated pesticides and herbicides, polyaromatic hydrocarbons (PAHs), solvents and disinfection by-products (DBPs), as well as inorganic substances like metals and nitrates. The risks posed by such chemicals to human health depend on three parameters: their concentrations in the water; their specific toxicity for both cancer effects and noncancer effects (e.g., birth defects, reproductive effects, neurotoxicity); and dose rate (the amount of substance entering the body over time). Pollutants in water can enter the body by ingestion of the water in drinks and food, by bathing and skin contact with the water, and by inhalation of the water vapor while showering.

Sanitation solutions for chemical agents combine prevention and cure tactics. Prevention includes minimizing the sources of pollution by substituting nontoxic substances and using cleaner, more efficient technologies. Cure consists of treating water to appropriate quality standards according to use (domestic, industrial, or agricultural). Water supply and wastewater treatment systems in developing countries must be affordable, cost-effective, and able to be maintained by local people.

The monitoring and enforcement of appropriate water quality standards is a vital part of sanitation. Diverse chemical and microbial standards seek to regulate important known risk agents, and acceptable levels must be monitored. In the United States, the Primary ("legally enforceable") Drinking Water Standards cover 60 organic chemicals, 20 inorganics, and 8 microbes/indicator organisms. The World Health Organization's Guidelines for Drinking-Water Quality includes over 60 organic chemicals (31 of them pesticides), 19 inorganics, 17 disinfectants and their by-products, and pathogens. However, although water quality laws exist in many developing countries, their enforcement is either weak or nonexistent, most often due to a lack of resources and political will.

The 1980s were designated the International Drinking Water Supply and Sanitation Decade by the United Nations. Despite the efforts of this campaign, however, in many countries more than half the rural populations are without adequate water supply access and sanitation. Many of the failures can be explained by weaknesses in the design and implementation of projects, as evidenced by many abandoned water and wastewater treatment plants. Such weaknesses often stem from a lack of maintenance caused by failures in equipment or training. A widespread lack of community participation in projects also helps explain failures. In most developing countries, the public sector provides facilities to central urban areas but

Table 2

World Sanitation Status
Country	W (%)	S (%)	U5MR	P	Country	W (%)	S (%)	U5MR	P	Country	W (%)	S (%)	U5MR	P
source: UNICEF 2000, multiple data compilation
Afghanistan	6	10	4	257	Ghana	65	32	49	105	Nigeria	49	41	15	187
Algeria	90	91	88	40	Guatemala	68	87	74	52	Oman	85	78	140	18
Angola	31	40	2	292	Guinea	46	31	14	197	Pakistan	79	56	33	136
Argentina	71	68	126	22	Guinea-Bissau	43	46	11	205	Palau	88	98	97	34
Bahamas	94	82	130	21	Guyana	91	88	60	79	Panama	93	83	133	20
Bahrain	94	97	133	20	Haiti	37	25	36	130	Papua New Guinea	41	83	45	112
Bangladesh	95	43	48	106	Honduras	78	74	81	44	Paraguay	60	41	100	33
Barbados	100	100	146	15	India	81	29	49	105	Peru	67	72	73	54
Belize	83	57	83	43	Indonesia	74	53	71	56	Philippines	85	87	81	44
Benin	56	27	22	165	Iran	95	64	100	33	Qatar	100	97	140	18
Bhutan	58	70	41	116	Iraq	81	75	37	125	St. Kitts and Nevis	100	100	90	37
Bolivia	80	65	57	85	Jamaica	86	89	149	11	St. Vincent/Grenadines	89	98	120	23
Botswana	90	55	77	48	Jordan	97	99	93	36	Sao Tome and Principe	82	35	61	77
Brazil	76	70	85	42	Kazakhstan	93	99	83	43	Saudi Arabia	95	86	113	26
Burkina Faso	42	37	22	165	Kenya	44	85	40	117	Senegal	81	65	38	121
Burundi	52	51	17	176	Korea, Dem. People's Rep.	100	99	104	30	Sierra Leone	34	11	1	316
Cambodia	30	19	24	163	Korea, Rep. of	93	100	175	5	Somalia	31	43	8	211
Cameroon	54	89	27	153	Kyrgyzstan	79	100	69	66	South Africa	87	87	58	83
Cape Verde	65	27	65	73	Lao People's Dem. Rep.	44	18	41	116	Sri Lanka	57	63	137	19
Central African Rep.	38	27	18	173	Lebanon	94	63	94	35	Sudan	73	51	43	115
Chad	54	27	13	198	Lesotho	62	38	33	136	Swaziland	50	59	53	90
China	67	24	79	47	Liberia	46	30	6	235	Syria	86	67	102	32
Colombia	85	85	104	30	Libya	97	98	117	24	Tanzania	66	86	32	142
Comoros	53	23	53	90	Madagascar	40	40	25	157	Thailand	81	96	90	37
Congo	34	69	47	108	Malawi	47	3	7	213	Togo	55	37	30	144
Congo, Dem. Rep.	42	18	9	207	Malaysia	78	94	153	10	Tonga	95	95	120	23
Cook Islands	95	95	104	30	Maldives	60	44	56	87	Tunisia	98	80	102	32
Costa Rica	96	84	145	16	Mali	66	6	5	237	Turkey	49	80	85	42
Côte d'Ivoire	42	39	28	150	Mauritania	37	57	16	183	Turkmenistan	74	91	66	72
Cuba	93	66	160	8	Mauritius	98	100	120	23	Tuvalu	100	78	71	56
Djibouti	90	55	26	156	Mexico	85	72	97	34	Uganda	46	57	35	134
Dominica	96	80	133	20	Micronesia	22	39	117	24	United Arab Emirates	97	92	153	10
Dominican Rep.	79	85	75	51	Rep. of Moldova	55	50	94	35	United States	100	100	160	8
Ecuador	68	76	89	39	Mongolia	45	87	28	150	Uzbekistan	90	100	70	58
Egypt	87	88	68	69	Morocco	65	58	67	70	Vanuatu	77	28	76	49
El Salvador	66	90	97	34	Mozambique	46	34	10	206	Venezuela	79	59	115	25
Equatorial Guinea	95	54	20	171	Myanmar	60	43	44	113	Viet Nam	45	29	85	42
Eritrea	22	13	45	112	Namibia	83	62	62	74	Yemen	61	66	38	121
Ethiopia	25	19	18	173	Nepal	71	16	51	100	Yugoslavia	76	69	130	21
Fiji	77	92	120	23	Nicaragua	78	85	77	48	Zambia	38	71	12	202
Gambia	69	37	59	82	Niger	61	19	3	280	Zimbabwe	79	52	55	89
W percentage of population with access to safe drinking water 1990-98
S percentage of population with access to adequate sanitation 1990-98
U5MR world ranking of under-five-year-old mortality (1998 data)
P 1998 under-five-year-old mortality: probability of dying between birth and 5 years old expressed per 1,000 live births

leaves rural and marginal urban areas underserved. A 1990 evaluation of water-decade achievements in rural Bangladesh revealed that even when safe water supply and sanitary latrines were provided, people did not always use them, while only a third of the household water supplies had adequate usage. This demonstrates the need for joint improvements in education and economic conditions to accompany investments in infrastructure.

A useful reference for the visualization of health-risk sources, diseases, and solutions is the water-wastewater cycle (see Figure 3). The cycle ideally consists of water supply parts and sanitation counterparts, with each stage (or lack of it) affecting others. It should be remembered that this engineered cycle operates within the natural constraints of a dynamic hydrological cycle that supplies water to plants and animals as well as

Figure 2

people. Human beings have coevolved with other species in these ecosystems, while at the same time becoming super-modifiers of them. Logically, the health of people is influenced by the condition of these ecosystems.

ENVIRONMENTAL SANITATION

Holistic environmental sanitation has four main water-related aspects: water supply, rainwater drainage, solid waste disposal, and excreta disposal.

Water Supply. The major problem for poor people in most countries is access to safe water in adequate quantity, with reasonable convenience, and at an affordable cost. Solutions include local grants to install household gutters and rainwater capture tanks; local wells designed to resist pollution; and small networks of water points served by a local well, borehole, or spring. The supply problems of major cities require integrated approaches that combine demand management, leak repair, backflow prevention, wastewater reuse, and the efficient, sustainable exploitation of sources.

Rainwater Drainage. Without adequate control of rainwater to mitigate floods and soil erosion, other sanitation measures can be nullified. People safe from floods and mudslides are more willing to invest in sanitation for their homes; and those in poor tropical urban areas attach a high priority to rainwater drainage. While local communities can build local drainage, downstream obstructions can cause the backing-up of channels and rivers, requiring a watershed-wide strategy.

Solid Waste Disposal. The interdependence of sanitation aspects is illustrated by the need for adequate solid waste removal to prevent the blockage of rainwater drains. Collection of refuse in hot climates must be frequent since piles attract flies and rats, and it should rely more on local labor-intensive methods rather than on expensive trucks. For the operation to be successful requires close cooperation between the users and providers of the service, and financing must come either from municipal recurrent funds and/or user fees.

Excreta Disposal. Large sewerage infrastructure projects tend to be too expensive for the vast majority of urban and rural people in developing countries, and it may be impossible to build a sewage network infrastructure in congested, narrow streets. On-site options include latrines, pourflush toilets, and septic tanks. There should be evaluated at each location according to needs and priorities. As water use grows in villages and towns, wastewater from washing and bathing (sullage) can be cost-effectively handled by a separate drainage system coupled to on-site excreta disposal.

TOWARD LASTING SANITATION

Sanitation, including water supply, is a major part of the United Nation's 1992 Agenda 21, a "Blueprint for Sustainable Development." The paradigm of sustainable development focuses on how to satisfy the basic needs of the present human population, and also secure resources to satisfy the needs of future generations. Growing population pressure, persistent poverty, and ecological degradation call for new integrated solutions to sanitation problems that strengthen both socio-economic and technical elements, including the following:

Financial, political, and societal will to invest in public health and the environment.
Human resources and public awareness through education and training.
Information resources—on health, water cycle, and ecological monitoring—for informed planning and actions.
Regulatory frameworks, enforcement, and compliance.
Basic sanitation infrastructure suited to local priorities and conditions.
A market for public health and environmental support goods and services that provide economically viable, effective, and lasting sanitation strategies.

Figure 3

These elements are interdependent. For example, adequate training improves monitoring and the operation and maintenance of infrastructure; and effective, enforced regulations stimulate a market and long-term investment. In India, state water boards were established to prevent pollution under the 1974 Water Act, closely modeled on systems in Great Britain. However, despite good scientists and engineers on staff, the chronic shortage of funds means controls have a limited effect on sanitation.

Above all, the support and involvement of the local community are essential if sanitation is to work. Ideally, many social sectors should be involved, to varying degrees, in community-driven ("bottom-up") sanitation projects. Sanitation users, water and public health regulators and administrators, health professionals, sanitation engineers, ecologists, researchers and scientists, financing agencies and donors, nongovernmental organizations, and suppliers of health and sanitation products and services can all contribute to a successful project. These new approaches reflect the trend away from professionally centered, curative methods and towards multi-stakeholder preventive strategies. To face these challenges, public health professionals and institutions need to play an expanding role as facilitators and promoters of this trend, building new partnerships in developing and developed countries. Protecting public health and ecological integrity are ethical and practical imperatives to be viewed as opportunities for people from diverse cultures, social groups, and disciplines to work more closely together.

Timothy J. Downs

I. H. Suffet

(see also: Chlorination; Drinking Water; E. Coli; International Development of Public Health; Rural Public Health, Sanitation; Sewage System; Wastewater Treatment; Waterborne Diseases; Water Quality; Water Treatment )

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Encyclopedia of Public Health