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Infection rates and preventive care

The negative effects of infection on nutrition are well established, as are impairments in immune functions that accompany moderate and severe nutrition deficiencies. The repeated occurrence of acute infectious episodes, as well as the establishment of chronic infection, markedly diminishes the adequacy of a diet for infected individuals and undermines their nutritional status. This, in turn, increases susceptibility to and severity of infection.

Diarrhosa, fever, and other illnesses in children

Few data allow adequate comparisons of the prevalence of diarrhoea, fever, and other illnesses and symptoms among urban and rural populations. Table 3 presents data on recall of recent disease episodes in children from selected countries. The samples were chosen from the poorest sections of urban or pert-urban areas. The data show a marked similarity of means for each country's urban and rural samples. Within each setting, however, the range is much larger, indicating that other variables carry more weight in determining the health of the population than urban or rural residence. The slightly larger rural than urban ranges suggest greater disparities of rural condition.

High coverage by immunizations against the communicable diseases of childhood is a safeguard for better nutrition and health. The urban setting presents advantages for achieving effective rates of immunization. Finally, in areas of the world where malaria, schistosomiasis, and other intestinal and systemic parasitic diseases are prevalent, urban settings generally afford greater protection.

Urban-rural mortality

United Nations Demographic Yearbooks for the years 1967 to 1985 are the principal source of data for this section. Table 4 shows urban and rural mortality rates by age and sex for groups of countries categorized by type and level of economic development.

Infant mortality

Table 5 shows urban and rural infant mortality rates for countries from which such data were available either for a specific year or as an average of a five year period. Some of the information is out of date, but it is still useful in terms of urban-rural behaviours. The following aspects are clear.

The range of infant mortality rates in the urban areas of less-developed countries is 12 times as great as that in developed countries and almost twice as great as that in those with centralized economies and intermediate development. In the rural areas the range is 25 times as great in less-developed as in developed countries.

The median values for the infant mortality rates in the emerging nations are five and eight times as great as in the developed countries for the urban and rural samples respectively. Again the countries with centralized economies and intermediate development fall in between but are closer to the developed countries' figures.

The differences between urban and rural rates by groups of countries amount to 40%, the rural population in underdeveloped nations being higher when the medians are compared: 69 deaths per 1,000 live births for the urban sample and 96% per 1,000 for the rural. If a difference of 5 deaths or more per 1,000 live births is considered significant, 10 countries have higher urban than rural infant mortality rates, and 28 countries have higher rural rates.

TABLE 4. Urban and rural mortality rates (deaths per 1,000) by age and sex group and country's type of development

a."Centralized and intermediate", -centralized economies and countries with intermediate development.

TABLE 5. Urban and rural infant mortality rates in selected countries, classified by type of development

Source: UN Demographic Yearbooks, 1967-1985.

a. Source: Ref. 36.
b. Average of various estimates.

Countries in the Western Hemisphere have both lower infant mortality rates and smaller urban-rural differences than countries in Africa and Asia. In the countries with centralized economies and intermediate development, 5 of 10 have urban-rural differences of more than 5 per 1,000, all having a higher rate in the rural population. None of the 13 developed countries has an urban-rural difference greater than 5 per 1,000 or an infant mortality rate greater than 20 per 1, 000.

The question of intra-urban variability must again be considered. There are some important reports in this regard: Basta [35] compiled data from Manila showing that squatter settlements had clearly greater neo-natal (less than 28 days old) and infant mortality (deaths per 1,000 live births) than non-squatter residents. In Porto Alegre, Brazil, intra-urban differentials between shanty-town and non-shanty-town dwellers are similar [37].

This differential in infant mortality in urban settings also occurs in developed countries. For example, various components of infant mortality in United States cities from 1962 to 1967 demonstrated up to 1.7-fold and 2.5-fold differences 1381. In Boston between 1972 and 1979 the lowest socio-economic group had close to two times greater mortality for children throughout the first year of life [39]. The greatest differentials in death rates occurred for in fonts 0 to 7 days old, where a substantial interaction between income level and black race produced the highest mortality. Low birth weight (82% due to premature delivery) explained the majority of the mortality among infants 0 to 27 days old. After that age, respiratory disease was the major cause of death.

The classic study on infant mortality in the Americas by Puffer and Serrano [40] provided a wealth of reliable data regarding urban and rural settings in six Latin American countries plus data on urban mortality in nine cities in other countries, including Sherbrook, Canada, and San Francisco, USA. Tables 6 and 7 summarize pertinent data from the study, which unfortunately did not consider subgroups within the urban or rural areas. It is evident that, except in Chile and Jamaica, infant mortality is significantly higher in the rural than in the urban areas; postneonatal mortality (between 28 and 365 days of age) is higher in rural areas in all countries except Jamaica, where the difference is minimal. The underlying causes of death are primarily infectious diseases; but, as associated causes, infection and nutrition have similar weight in infant deaths. In general, the rural populations have higher proportions of infectious diseases and nutrition deficiencies as causes of death. There are no clear urban-rural differences in immaturity as an associated cause, while it is slightly more important as an underlying cause of death in the rural area.

Two additional factors deserve special mention as determinants of the infant mortality rate: the education of the mother and the availability of medical care. Many studies have found that infant mortality rates and undernutrition are inversely related to maternal education, whether the setting is urban or rural [40-46].

TABLE 6. Mortality in children younger than five years old, 1968-1970

U = urban; R = rural.

Source: Ref. 40.

TABLE 7. Underlying and associated causes of infant mortality (percentages of deaths)

U = urban; R = rural.
a. Infectious diseases and diseases of the respiratory system.

Source: Ref. 40.

FIG. 1. Childhood mortality in Peru by place of residence and education of the mother (Source: Ref. 45.)

In Peru, maternal education is a better discriminant than place of residence (urban or rural) for the infant mortality rate [45] (fig. 1). In the urban setting, primary education of the mother was associated with a 37% lower infant mortality rate than that for children of mothers with no schooling, and secondary education was associated with an additional 50% reduction from the rate for the children of mothers with only primary education. Mortality of children of mothers without schooling was 5.3 times as high as among those whose mothers had secondary education. In the rural setting, primary education was associated with a 57% lower infant mortality rate [46].

Data for Sri Lanka show that both maternal literacy and paternal completion of primary education interact [41]. In the urban setting the latter appears associated with greater differentials in infant mortality rates than the former. In estate (plantation) rural settings, paternal education appears to have no effect when the mothers are illiterate. These examples demonstrate the complexity of interactions among variables associated with the education of mothers or parents in relation to infant mortality.

With regard to availability of medical care, adequate prenatal care can diminish maternal and infant deaths, particularly in the perinatal period. It also can help reduce the rate of prematurity and low birth weight, although these are more effectively prevented by nutritional and hygienic measures throughout pregnancy and, ideally, before. In India medical care may be the critical factor in explaining mortality differentials between Kerala and West Bengal, and simple treatments for the common infectious diseases are very effective [47]. Literacy in Kerala is higher, particularly among females. Environmental sanitation, income expenditure, income distribution, nutrition, industrialization, and urbanization may be discounted as determinants of mortality differentials in that setting [47].

The argument that medical care is the most effective measure to control infant mortality has been used mistakenly and enforced during economic crisis in less-developed nations in order to keep infant deaths under control when scial and preventive programmes are reduced. In the long run, poor investment in preventive programmes leads to deterioration in health and nutrition even when infant mortality rates improve [24].

Several of the studies cited above make an important observation: A large proportion of the infant mortality rate in any of the sites studied is concentrated among a small proportion of women whose profile is one of high risk for infant mortality [40, 46]. It is also clear from several studies that the undesirable effects of recession are magnified tenfold in terms of distress among urban and rural poor in less-developed nations [48]. Moreover, this distress may affect the poor in those countries even when the gross national product at the national level may be increasing [49]. This maldistribution of income has given rise to elevations in infant mortality rates among the affected population.

TABLE 8. Prevalence of chronic PED (based on height for age) and acute PED (based on weight for height) among children under five or six years old in selected countries

a. Mostly subsistence agriculture with some cash crops.
b. Total urban sample.

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