Sudan in the light of its national censuses, with special reference to the 1983 census

"The aim of this paper is to examine Sudan's development conditions, using its national censuses as indicators of the status of the country, with special reference to the 1983 census, the last census in Sudan." The importance of taking migration into account when examining the prospects for development is stressed. The author also describes available demographic data sources for the Sudan, including the censuses of 1955-1956 and 1973. Sections are included on population size and growth, sex and age distribution, spatial distribution, population density, mortality, migration, illiteracy, and the labor force.

Bacterial indicators of risk of diarrhoeal disease from drinking-water in the Philippines

Inadequate measures of water quality have been used in many studies of the health effects associated with water supplies in developing countries. The present 1-year epidemiological-microbiological study evaluated four bacterial indicators of tropical drinking-water quality (faecal coliforms, Escherichia coli, enterococci and faecal streptococci) and their relationship to the prevalence of diarrhoeal disease in a population of 690 under-2-year-olds in Cebu, Philippines. E. coli and enterococci were better predictors than faecal coliforms of the risk of waterborne diarrhoeal disease. Methods to enumerate E. coli and enterococci were less subject to interference from the thermotolerant, non-faecal organisms that are indigenous to tropical waters. Little difference was observed between the illness rates of children drinking good quality water (less than 1 E. coli per 100 ml) and those drinking moderately contaminated water (2-100 E. coli per 100 ml). Children drinking water with greater than 1000 E. coli per 100 ml had significantly higher rates of diarrhoeal disease than those drinking less contaminated water. This threshold effect suggests that in developing countries where the quality of drinking-water is good or moderate other transmission routes of diarrhoeal disease may be more important; however, grossly contaminated water is a major source of exposure to faecal contamination and diarrhoeal pathogens.

Epidemiology and transmission of rotavirus infections and diarrhoea in St. Lucia, West Indies

To determine the epidemiology and risk factors of rotavirus infections in St. Lucia, 229 children in three valleys with varying levels of sanitation were studied for 2 years. A four-fold rise in complement fixation antibody to rotavirus antigen was used in paired samples as evidence of recent infection. Results showed that forty-eight per cent of infants experienced at least one infection during a two-year period, and 17% of children were reinfected. Infections occurred within the first months of life and peaked between 6 and 23 months of age. The peak infection coincided with the dry season in each age group. Children breast-feeding had fewer infections. Although crowding within the home was significantly associated with repeated infection, the incidence of infection was not affected by the degree of sanitation. Other studies in the region, using recently developed techniques, concur with these findings which advance our understanding of the epidemiological importance of rotavirus in St. Lucia. Although these studies provide insights into the risk factors for rotavirus infections, other studies are required to determine whether investments should be focused on improved sanitation or immunization or both.

Population density and cancer mortality differentials in New York State, 1978-1982

Patterns of cancer mortality within five population density quintiles in Upstate New York (New York State, exclusive of New York City), were investigated between 1978 and 1982. Sex-specific standardized mortality ratios (SMRs) were calculated within each population density quintile for all cancer deaths combined and for site-specific cancer deaths based on cancer mortality patterns exhibited by the general population of New York State, exclusive of New York City. Areas with the highest population density demonstrated a 12% excess of cancer deaths among males and a 6% excess among females. In contrast, areas with the lowest population density exhibited lower cancer mortality, among both males (9% less) and females (7% less). Males demonstrated a significant linear relationship between increasing population density and deaths for all cancer sites combined and for cancers of the oral cavity and pharynx, oesophagus, stomach, colon, gallbladder, pancreas, lung, prostate, and kidney. Among females, a significant linear relationship was observed between increasing population density and deaths for all cancer sites combined and for deaths due to cancers of the stomach, colon, liver and breast. Deaths due to cancers of the rectum, malignant melanomas of the skin, and cervix also exhibited unusual patterns of mortality across the population density quintiles. These data are most useful in generating hypotheses for further studies to define specific aetiological factors operating within population density groupings. Population density, as measured in this investigation, may represent a surrogate measure for other factors which are related to cancer morbidity and cancer mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

The epidemiology of acute respiratory infections in children and adults: a global perspective

While a number of advances have been made in our understanding of the epidemiology of acute respiratory infections in the past two decades, a number of serious questions still require urgent answers. The associations of factors such as chronic disease in adults, direct smoking, passive smoking, crowding, and breast feeding to acute respiratory infections are now well documented. Appropriate changes in public health policy need not be predicated on results from still further studies. However, in virtually all of the other areas cited in this review, further data are required. In developing countries, studies being currently conducted on vitamin A supplementation, malnutrition, and indoor air pollution will help address the most pressing issues. More studies are also needed on the relations between HIV infection and acute respiratory infections, as well as low birth weight and respiratory infection. The National Research Council studies have provided important additional data on etiologic agents in children in developing countries, but data on adult pneumonia remain sparse. In developed countries the issues that may be of greatest interest are the relation between maternal antibody levels and passive immunity in infants, the reasons for the increase in pneumonia mortality in older age groups, and the relation between air pollution and acute respiratory infections (as opposed to morbidity from bronchial reactivity). From a methodological viewpoint, the relation between previous respiratory infection (particularly in the first year of life) and subsequent acute respiratory infection morbidity has been inadequately explored. Adjustment for autocorrelation in multivariate models may be necessary if this relation is strong. Greater standardization of data collection methods in developed and developing countries also needs to be more seriously addressed. Given that some advances have been made in this area, the time may be right for development of acute symptom questionnaires, akin to the American Thoracic Society chronic respiratory questionnaire, for use in both developed and developing countries. Standardization of diaries, although somewhat more difficult, would also be extremely useful in many instances.

An epidemic model with a density-dependent death rate

This paper deals with a mathematical model for a disease where the death rate depends on the number of people in the population. This sort of model would be suitable for diseases in developing countries or for diseases amongst animal and insect populations. We also assume that the population under consideration is regulated by the disease so that there is a mortality induced by the disease. We use a compartmental model and perform an equilibrium and stability analysis to find that there is a threshold condition. If the threshold is exceeded, then there is a unique equilibrium with disease present which is locally stable to small perturbations. We conclude by looking at several specific models and seeing how the results relate to previous work.

Population change and environment in central and eastern Kenya

"This paper, in compiling a case-study of six districts in Central and Eastern Provinces of Kenya, addresses the two poles of theory regarding population, environment, and economy--restricted growth and degradation versus induced change and intensification. The paper presents data on population change, and explores its relevance for changing patterns of resource use and economic opportunity.... Changes in population density between the 1969 and 1979 censuses are compiled, using regions of agroclimatic potential as surrogates for indicators of economic development.... Trends in urbanization are also analysed, to illuminate the dynamics of rural-urban linkages."

The perceived burden of children

We expect that mothers vary in the degree to which they perceive their children as burdensome, and that this variation may help explain why past research on the effect of children on mothers' psychological distress often finds insignificant or inconsistent effects: mothers who feel their children are a burden may have high distress levels compared with mothers who do not feel burdened. We find that mothers experience their children as differentially burdensome at different stages in the life cycle: younger mothers' perceived burden increases with each additional child, but older mothers are less affected by increasing numbers of children. Preschool children increase all mothers' perceived burden because they tend to make mothers feel that they cannot be alone when they want to. Employed mothers feel less burdened by their children than the nonemployed. Social context - the density of people in the home, integration into the neighborhood, and the presence of relatives in the area - had a number of unexpected effects. Crowding in the home increased the perception that children are burdensome by way of subjective crowding - the perception that there is too much activity in the home, the perceived inability to be alone, and dissatisfaction with living space. However, controlling for subjective crowding, the more adults in the home, the less the burden of children, presumably because these other adults can help care for the children. Integration into the neighborhood increased the likelihood of sharing child care with friends and neighbors, but this shared child care increased the perception of burden. We had expected the opposite. Possibly it increases perceived burden because it increases the obligation to care for one's neighbors' children in return for their help. Having relatives in the area increased the likelihood that these family members would care for one's children, but this child care had no significant effect on reducing burden. Instead, relatives in the area increased a mother's perception that she could not be alone when she wanted to, which increased burden. Thus, we find a number of costs of social integration for mothers.

[The geographical distribution of fertility around Mexico City]

A spatial analysis of fertility around Mexico City reveals an "inverted U" pattern which appears, on the face of it, inconsistent with both conventional economic location analysis and a spatial diffusion process. A closer examination of the problem implies that economic variables, when integrated in a proper model, may account for the observed cross- sectional spatial pattern, whereas pure diffusion can not. Spatial diffusion, however, may be responsible at least in part for the observed fertility changes over time. The geographical patterns of fertility in 2 states neighboring Mexico City (Mexico and Hidalgo) are examined empirically. The interpretation of the nonmonotonic distance effect is that there are significant locational advantages to childbearing at medium distances that are not enjoyed at households location either very close or far away from the city.