Water and Sanitation-Related Diseases and the Changing Environment

Challenges, Interventions, and Preventive Measures

Janine M. H. Selendy, Janine M. H. Selendy

• Éditeur: Wiley-Blackwell
• Année: 2018
• ISBN:
  9781119416180
• Édition: 2
• Sujet: Scienze biologiche
• Sous-sujet: Microbiologia

The revised and updated second edition of Water and Sanitation Related Diseases and the Changing Environment offers an interdisciplinary guide to the conditions responsible for water and sanitation related diseases. The authors discuss the pathogens, vectors, and their biology, morbidity and mortality that result from a lack of safe water and sanitation. The text also explores the distribution of these diseases and the conditions that must be met to reduce or eradicate them. The text includes contributions from authorities from the fields of climate change, epidemiology, environmental health, environmental engineering, global health, medicine, medical anthropology, nutrition, population, and public health. Covers the causes of individual diseases with basic information about the diseases and data on the distribution, prevalence, and incidence as well as interconnected factors such as environmental factors. The authors cover access to and maintenance of clean water, and guidelines for the safe use of wastewater, excreta, and grey water, plus examples of solutions. Written for students, and professionals in infectious disease, public health and medicine, chemical and environmental engineering, and international affairs, the second edition of Water and Sanitation Related Diseases and the Changing Environment isa comprehensive resource to the conditions responsible for water and sanitation related diseases.

SECTION II
WATER AND SANITATION‐RELATED DISEASES

7
INFECTIOUS DIARRHEA

Sean Fitzwater¹, Anita Shet², Mathuram Santosham², and Margaret Kosek²

¹ Department of Pediatrics, University of California, Los Angeles, Los Angeles, CA, USA

² Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA

7.1 INTRODUCTION

Diarrhea is one of the leading causes of morbidity and death globally. Children and young infants are at highest risk. The majority of diarrheal illnesses are caused by viral, bacterial, and parasitic pathogens, which disrupt the gut’s normal secretory and absorptive functions. Most infectious diarrheal episodes are acute in nature and can lead to rapid loss of bodily fluids, dehydration, and death if proper supportive care is not provided promptly. Repeated bouts of acute diarrhea and persistent 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 diarrheal illnesses can be successfully managed using oral rehydration therapy and, in severe cases, with intravenous therapy. In cases of dysentery and cholera, antimicrobial therapy is indicated. 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 led to a dramatic reduction in diarrheal deaths over the last three decades, most notably in children. In the early 1980s approximately 5 million pediatric diarrheal deaths were estimated to occur; by 2015 there were less than 600 000 deaths a year from diarrhea in children.

7.2 EPIDEMIOLOGY

Infectious diarrhea is a leading cause of disease and death worldwide. Each year there are approximately 2.4 billion episodes of diarrhea resulting in 1.3 million deaths [1]. Globally, infectious diarrhea is responsible for 2.3% of all deaths. Most of this morbidity and mortality occurs among young children (Table 7.1). In 2015 the average child under the age of five had a mean of 1.4 episodes of diarrhea each year, which led to an estimated 498 000 deaths, making diarrhea the fourth most common cause of under‐five deaths [1].

TABLE 7.1 Morbidity and mortality associated with diarrheal disease stratified by age group.

Source: Number of deaths adapted from The Global Burden of Disease: Update 2015; WHO [1].

Age group (years)	Deaths	Deaths (per 100 000)	Cases (millions)	Cases (per person)
0–4	498 641	74.7	955	1.43
5–14	51 611	4.2	394	0.32
15–49	171 438	4.6	679	0.18
50–69	223 527	18.1	213	0.17
>70	365 762	93.8	145	0.37

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 [2]. As a result, the burden of diarrheal illnesses varies widely globally (Table 7.2 and Figure 7.1). The highest incidence of diarrheal disease occurs in low‐ and middle‐income countries that 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 (Figure 7.2). The WHO estimates that in 2015, over 98% of deaths due to diarrhea occurred in low or low‐middle‐income countries [1]. In total, the 10 countries with the highest number of deaths due to diarrhea (India, Nigeria, Indonesia, Pakistan, Ethiopia, Democratic Republic of the Congo, Kenya, Niger, Tanzania, and Chad) accounted for 71% of all diarrheal deaths globally [1]. By comparison, less than 27 000 deaths due to diarrhea occurred in all high‐income countries combined. Although diarrhea rarely causes death in high‐income countries, it still is a significant health problem and accounts for considerable utilization of healthcare services. In the US, between 1997 and 2000, there were 150 000 childrenhospitalized each year with diarrhea, accounting for 13% of all hospital admissions for children under five years old [3].

TABLE 7.2 Morbidity and mortality associated with diarrheal disease stratified by income group.

Income group	Deaths (total)	Deaths (per 100 000)	Cases (millions)	Cases (per person)
High	26 481	2.2	21	0.02
Upper middle	57 123	2.2	364	0.14
Lower middle	890 597	30.4	1454	0.50
Lower	336 779	55.4	546	0.90
Global	1 310 980	18.0	2386	0.33

(Number of deaths and cases adapted from The Global Burden of Disease: Update 2015; WHO [1]. Income stratification is based on World Bank classification, 2015).

FIGURE 7.1 Incidence on diarrhea per population.

Source: Adapted from The Global Burden of Disease: 2015 Update; WHO [1].

FIGURE 7.2 Rate of death due to diarrhea per 100 000 population.

Source: Adapted from The Global Burden of Disease: 2015 Update; WHO [1]. Population estimates from World Bank database 2015.

The burden of diarrheal disease varies within countries, with the highest rates of disease and deaths occurring in impoverished and neglected populations [4, 5]. 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 the elderly. In the United States, Native American and Alaskan Native infants have higher rates of diarrhea‐associated outpatient visits than the general population [6]. In all countries, natural disasters and other humanitarian crises put populations at increased risk of diarrheal disease by breaking down the regular sanitation infrastructure, displacing populations, and facilitating the spread of pathogens while concurrently interrupting access to optimal case management [7]. In ...