Diarrheal Diseases and Child Morbidity and Mortality

Diarrheal diseases remain one of the most important public health problems in the world. These diseases, commonly defined by an increase in the frequency and fluidity of bowel movements relative to the usual pattern of each individual, have been found to be major contributors to illness and death, particularly in children in developing countries. Recent estimates by the World Health Organization suggest that children of developing countries have three-quarters of a billion episodes of diarrhea each year, causing nearly 5 million deaths (Snyder and Merson, 1982). For the children of developing countries it is obvious that exposure and response to diseases are conditioned by their social, economic, and environmental milieu. In Addis Adaba, for instance, the prevalence of diarrhea was found to vary according to housing conditions and parental education (Freij and Wall, 1979). In Bangladesh several specific types of diarrhea had higher incidences and longer durations in children from low-income households (Becker, Black, and Brown, unpublished research). These differentials in rates of disease by socioeconomic variables may be due to differences in child care practices, such as preparation of weaning foods, boiling of drinking water, or personal hygiene (Black et al., 1983). On the other hand, they may be due to low-income children's poorer nutritional status, a factor known to be associated with more prolonged diarrhea (Black et al., 1984a). Since the diarrheal diseases are comprised of many specific types of illnesses caused by diverse bacterial, viral, and parasitic enteropathogens with differing modes of transmission, the relationship between the diarrheal diseases and socioeconomic and environmental variables can be determined only if the epidemiology of the diarrheal diseases themselves is better understood. Until the last several years, studies of children in developing countries had been able to detect a potential causal agent in fewer than 20 percent of