Water and Sanitation-Related Diseases and the Environment

Challenges, Interventions, and Preventive Measures

Janine M. H. Selendy

• Publisher: Wiley-Blackwell
• Year: 2011
• Print ISBN: 9780470527856
• eBook ISBN: 9781118148600
• Edition: 1
• Topic: Ciencias biológicas
• Subtopic: Microbiología

Written by authorities from various related specialties, this book presents the most complete treatment possible of the conditions responsible for water- and sanitation-related diseases, the pathogens and their biology, morbidity and mortality resulting from lack of safe water and sanitation, distribution of these diseases, and the conditions that must be met to reduce or eradicate them. Preventive measures and solutions are presented throughout. This book is an essential resource for all graduate students, postdoctoral scholars, and professionals in infectious disease, public health and medicine, chemical and environmental engineering, and international affairs.

Key features:

• Provides a comprehensive understanding of the interconnection among many factors related to water-related diseases, sanitation and hygiene
• Brings together experts from various specialties to address each area covered and to assist in bringing about the understanding of those interconnections
• Provides examples of successful interventions with knowledge about how they were brought about so that information can be use to replicate the initiative in full or in part
• Provides an appreciation of the concerns and solutions addressed from an international perspective with high and low technological solutions
• Provides insight into the international dimension of these concerns and how they can be best addressed

Section II
Water and Sanitation-Related Diseases

The chapters in this section on individual diseases not only cover basic information about the disease in question, that is, pathogen, epidemiology, clinical manifestations, treatment, prevention, and control but also distribution, prevalence, and incidence and interconnected factors such as environmental factors. These chapters, as appropriate, discuss and emphasize the significance of the close relationships among water access and quality, lack of adequate sanitation, lack of adequate hygiene, and the relationship of human activity to the diseases. They address how the diseases are further aggravated by nutritional inadequacies and anemia, infections, and other problems that often exist in the same person, such as diarrheal diseases. Other factors they address are the importance of adequate maternal and child health care, the significance of climate change, and other environmental factors. Prevention and control are important parts of the discussions in this section.

Chapter 5
Infectious Diarrhea

Sean Fitzwater, Aruna Chandran, Margaret Kosek and Mathuram Santosham

5.1 Introduction

Diarrhea is one of the leading causes of morbidity and death globally, disproportionally affecting young children and developing countries. The majority of diarrheas are gastrointestinal infections caused by viral, bacterial, and parasitic pathogens, which disrupt the gut's normal secretion and absorption functions. Most infectious diarrhea episodes are acute in nature, and can lead to rapid loss of bodily fluids, dehydration, and death if proper supportive care is not provided. Repeated bouts of acute diarrhea and chronic diarrhea can exasperate malnutrition and lead to poor growth, impaired immune function, and increased susceptibility to diarrhea as well as other infections. Fortunately, most infectious diarrhea can be successfully managed. Uncomplicated diarrhea can be easily managed with a simple regimen of oral rehydration and nutritional therapies, while severe dehydration may require intravenous (IV) fluids; for cholera or dysenteric diarrhea, such as shigellosis, antibiotics are recommended in addition to rehydration. Diarrhea can be prevented to a large extent by disrupting transmission of pathogens through vaccination against leading pathogens, nutritional interventions, and sanitary interventions including improving personal hygiene, water quality, disposal of waste, and appropriate preparation of food. Together, improved case management and prevention of diarrhea has lead to a dramatic reduction in diarrheal deaths over the last several decades, although progress has stagnated in recent years. Diarrhea morbidity has not seen similar improvements on the global scale, although targeted interventions are clearly efficacious.

5.2 Epidemiology

Infectious diarrhea is a leading cause of disease and death worldwide. Each year there are approximately 4.6 billion episodes of diarrhea, resulting in 2.2 million deaths (1). Globally, infectious diarrhea is responsible for 3.7% of all deaths, ranking 5th in terms of leading cause of death (1). Most of this morbidity and mortality occurs among young children (Table 5.1). In 2004, the average child under the age of 5 had a mean of 3.8 episodes of diarrhea, leading to an estimated 1.7 million deaths (1), making diarrhea the second most common cause of childhood mortality, responsible for 18% of all deaths in children under age 5 (2).

Table 5.1 Morbidity and Mortality Associated with Diarrheal Disease Stratified by Age Group.

Multiple factors are associated with increased risk of diarrheal diseases, including lack of access to clean water, inadequate disposal of human waste, overcrowding, limited quality control in food handling and processing, and malnutrition (3). As a result, the burden of diarrheal illnesses varies widely globally (Table 5.2 and Fig. 5.1). The majority of diarrheal cases and highest incidence of disease occur in low- and middle-income countries, which lack basic sanitary preventive measures. Additionally deaths due to diarrhea occur almost exclusively in low- and middle-income countries due to lack of access to appropriate medical care (Fig. 5.2), countries where WHO estimates that in 2004 over 99% of deaths due to diarrhea occurred (1). In total, the 10 countries with the highest number of deaths due to diarrhea (India, Nigeria, Ethiopia, the Democratic Republic of the Congo, Afghanistan, Bangladesh, Pakistan, China, Angola, and Niger) accounted for 57% of diarrheal cases and 62% of diarrheal deaths. By comparison, less than 14,000 deaths due to diarrhea occurred in 2004 in all high-income countries combined (1). Although diarrhea rarely causes death in high-income countries, it still accounts for a significant health problem and utilization of health care services. In the United States alone, 150,000 children are hospitalized each year with diarrhea, accounting for 13% of all hospital admissions for children under 5 years old (4), but only 30 deaths (1).

Table 5.2 Morbidity and Mortality Associated with Diarrheal Disease Stratified by Income Group.

Figure 5.1 Incidence on diarrhea per population. (Adapted from Ref. (1).)

Figure 5.2 Rate of death due to diarrhea age per 100,000 population. (Adapted from Ref. (1).)

The burden of diarrheal disease varies within countries, with the highest rates of disease and deaths occurring in impoverished and neglected populations (5, 6). In high-income countries, minority populations tend to have higher rates of diarrhea than the general population due largely to poorer socioeconomic conditions, although most severe disease in all social strata are concentrated in children and elderly. In the United States, Native American and Alaskan Native infants have nearly twice the rate of hospitalizations due to diarrhea compared with the general U.S. population (7). In all countries, natural disasters and other humanitarian crises put populations at increased risk of diarrhea disease by breaking down the regular sanitation infrastructure, displacing populations, and facilitating the spread of pathogens while concurrently interrupting access to optimal case management (8). In Bangladesh, the floods of 1988, 1998, and 2004 resulted in a doubling of diarrheal cases seen at the International Center for Diarrheal Disease Research, from an average of 249 cases per day during nonflood times to 542 cases per day during flooding (9). Well-planned responses to crises have been shown to limit the mortality caused by diarrhea. A study of refugee camps in Tanzania from 2005 to 2007 found increased rates of diarrheal illness compared to the general population, but a decreased risk of death. The rate of death in refugee camps varied yearly from 0.05 to 0.07 death per 1000 diarrheal cases, while the national average was over 12 times higher (0.88 per 1000) (10).

5.3 Definition and Physiology

Diarrhea is defined by the WHO as a condition in which the stricken person has at least three loose or watery stools per day (11), often accompanied by an increased sense of urgency, abdominal discomfort, and alterations in stool characteristics (12). These symptoms are caused by an alteration in the gastrointestinal tract's ability to absorb nutrients, augmented secretion of fluids, or both. Infectious agents create this state through a combination of inflammatory and noninflammatory processes (13).

Noninflammatory processes leading to diarrhea are noninvasive and are caused by enterotoxin-producing organisms or by organisms that disrupt the normal absorptive or secretory functions of the intestinal lining without causing significant inflammation or mucosal damage (13). A variety of pathogens produce enterotoxins, substances that change the permeability of the cells lining the intestinal tract by altering the function of specific cellular pathways (14–17). The specific target of an enterotox...

Table of contents

• Cover
• Table of Contents
• The DVD accompanying this book presents
• Title
• Copyright
• Preface
• Contributors
• Introduction
• Section I: Defining the Problem
• Section II: Water and Sanitation-Related Diseases
• Section III: Water Resources
• Section IV: Sanitation and Hygiene
• Section V: Environmental Factors of Water Pollution
• Section VI: Current and Future Trends in Preventing Water Pollution
• Section VII: Emerging Issues in Ecology, Environment, and Disease
• Section VIII: Conclusion
• Color Plates
• Index
• End User License Agreement