Seroprevalence of HIV infection in rural South Africa.

OBJECTIVES: To establish the prevalence of HIV infection in rural South Africa and to investigate demographic factors that influence this prevalence. DESIGN: An anonymous HIV seroprevalence survey was performed in conjunction with a population-based malaria surveillance programme. SETTING: The rural area of northern Natal/KwaZulu, South Africa. PARTICIPANTS: A total of 5023 black African participants were recruited by malaria surveillance agents during house-to-house visits; each house in an endemic malaria area is visited approximately once every 6 weeks. Participants included 4044 healthy and 979 febrile individuals (i.e., suspected of having malaria). MAIN OUTCOME MEASURES: HIV-1 and HIV-2 serological status, degree of mobility, age and sex. RESULTS: Sixty of the 5023 blood specimens were confirmed to be HIV-1-antibody-positive by Western blot, an overall prevalence of 1.2% (95% confidence interval, 0.9-1.5). None of the specimens was positive for HIV-2 antibodies. After adjusting for age, presence of fever and migrancy, women had a 3.2-fold higher prevalence of HIV-1 infection than men. HIV-1 infection was approximately three times more common among subjects who had changed their place of residence recently (2.9 versus 1.0%, P < 0.01). CONCLUSIONS: The prevalence of HIV-1 infection is higher among women than men resident in rural Natal/KwaZulu, South Africa. This is at least in part the result of oscillatory migration, particularly of men who work in urban areas but have families and homes in rural areas. Migration is associated with a higher prevalence of HIV-1 infection, suggesting that improving social conditions so that families are not separated and become settled in their communities is one way to help reduce the spread of HIV-1.

PIP: As part of a population-based malaria surveillance program in late 1990, surveillance agents took blood samples from 979 people who had had a fever within the last 2 weeks and from 4044 healthy people during regular house-to-house visits in rural northern Natal/KwaZulu, South Africa, to determine HIV seroprevalence and risk factors of HIV infection. 60 (1.2%) people were HIV-1 seropositive. No one had HIV-2 infection. Febrile people had a 30% higher sex-adjusted relative risk (RR) of HIV-1 infection than healthy individuals, but this increase was insignificant. Women were at greater risk of HIV-1 infection than men (1.6% vs. 0.4%; age-adjusted RR = 3.8). In fact, this risk still existed when the researchers controlled for fever (RR = 3.75) and migrancy (RR = 3.2). The fall in the RR for women from 3.8 to 3.2 when controlled for migrancy suggested an underrepresentation of migrant male workers in the study sample. 2.3% of the women in their childbearing years (15-44) were HIV-1 seropositive, indicating an increased likelihood of transmission of HIV-1 to newborns. The youngest person afflicted with HIV-1 was a 12-year-old female and the oldest was a 66-year-old woman. No 10-to-19-year-old males tested HIV-1 positive, while 1.7% of the 10-to-19-year-old females did, suggesting that the young females had sex with older men. This may have indicated teenage prostitution and sexual abuse. 2.9% of the people who changed their place of residence within the last year (migrancy) had HIV-1 infection. For women it was linked to a 2.4 times higher RR (age-adjusted) of HIV-1 infection. For men, the age-adjusted RR was even greater (7.3). Even though HIV-1 seroprevalence was about 45% greater in areas crossed by the main national road than it was in other areas (1.3% vs. 0.9%), the difference was not significant. Since migrants were a key source of HIV-1 infection, improvement in social conditions, allowing families to live together and to settle in their communities, may reduce HIV-1 transmission.

Growing pains in South America.

PIP: This article describes some negative effects from modernization and urban growth in South America, including disease, pesticides, occupational hazards, poor environmental controls of water and garbage, sanitation, and environmental degradation. South America is following the global trend toward urbanization and the problems that accompany it. Agricultural expansion led to an expanded market for pesticides that includes the deadly DDT, paraquat, and heptachlor. Brazil and Colombia are the largest consumers. Latin American officials justify use of DDT, which is banned in the US and many European countries, as an effective means of combating mosquitos that carry malaria. Exposure occurs during harvesting, transporting, forestry, livestock farming, and vector control activities. Methyl bromide, which is used post-harvest and as a soil fumigant, is dangerous enough to be banned in the US in 2001, and in developing countries in 2002. Exposure to toxic chemicals can severely inhibit enzyme action that is necessary for neurological functioning. A hot climate, which prevents protective clothing, lack of education on proper application, and absence of water to wash exposed skin, make pesticide protection very difficult. Over 40 million agricultural workers are at risk of pesticide poisoning. Habitat destruction has contributed to increased mosquito infestations. Children in the workplace are at even greater risk of noise pollution and chemical poisoning. South America pollutes almost 11 times more fresh water per capita than Europe. About 70% of domestic garbage is collected, and about 30% is disposed of correctly. Only 10% of urban wastewater is treated before discharge into waterways. The loss of coastal wetlands reduces the ability of waterways to filter and absorb nutrients. Environmental health problems suggest an interlinkage between environmental sustainability, human health, and economic growth.^ieng

Migration and redistribution of the elderly: a challenge to community services.

PIP: This article analyzes regional migration and redistribution patterns of the elderly in the United States for the 1960s and 1970s, assesses motives for elderly migration, and examines the implications of elderly migration for community services. The elderly population has increased in size 54.2% from 1960 to 1980 and will increase even more by natural increase as the baby boom ages. Although the elderly are less prone to migrate than younger age groups, their two major migration trends are a movement form the Northeast and Midwest to Sunbelt states and turnaround urban-rural migration. A redistribution index shows elderly redistribution as 3.41% for the U.S., with elderly populations growing consistently in the South and West since 1960 and in the East South Central since 1970. Younger elderly tend to move at retirement to Sunbelt states. They are similar to nonmigrant younger elderly in their communities but have greater income, education, and housing ownership, which provides a short-term advantage for communities. Older elderly are more likely to move for assistance from family or to return to a former home. The elderly have a proportionately much higher use of health services (including hospital stays and doctors' visits), nursing homes, and day care centers. Numbers of younger and older elderly per nursing home bed and adult day care center space is shown by region. The North Central has the best services in proportion to population, and the South is strongly deficient in nursing home beds. Despite recent increases in the elderly population in the South and West, they still have less than their share of elderly. Although the migration of younger elderly to the South and West has been beneficial to the communities so far, as younger elderly age, they may need far more intensive community services than now exist.^ieng

The impact of population redistribution on service delivery.

PIP: An attempt is made to assess the impact of the redistribution of the elderly population on service delivery in the United States. Data from the 1-in-100 public use sample of the 1970 census are used to examine variations in the number and the demographic, socioeconomic, and residential characteristics of older migrants in California and Florida. Comparisons are also made among in-migrants, out-migrants, and nonmovers.^ieng

Migration patterns among the elderly: a developmental perspective.

PIP: The elderly tend to make 3 kinds of moves when they migrate: 1) When they retire, 2) When they experience moderate forms of disability, and 3) when they have major forms of chronic disability. In the 1st type of move, the migrant's support needs do not require nearness of kin. These migrants tend to be younger, healthier, wealthier, and more often have intact marriages than migrants in the counter streams. The 2nd type of move is typically compounded when deficits from widowhood and disability are combined. They generally move nearer to their children. Older persons moving to retirement destinations like Florida should typify the 1st move, whereas those moving from Florida to northern urban areas should typify the 2nd and 3rd moves. Those moving from northern states to Florida tend to be younger than those moving from Florida to northern states. 15.5% of those moving to Florida are over 75 years old whereas 40.6% of those moving north from Florida are over 75. 47.8% of those moving north are widowed, but only 17% of those moving to Florida are widowed. Limited kin resources is the motive for the 3rd move. Most 3rd-stage moves are local rather than long distance. There are 2 groups who do not follow the same migration pattern despite facing similar social pressures to make the 3 basic moves: 1) those moving between metropolitan and non-metropolitan places and 2) migrants from abroad who join their families. Migrants from abroad tend to live with their children more and live independently less frequently than any of the migration comparison groups. They also have the highest proportion of persons receiving welfare income.^ieng

Population pressures in Latin America. [Updated reprint].

PIP: This publication examines the main demographic changes in Latin America since World War II, and considers their social and economic impact on the region. The paper looks at the following demographic trends: population growth, fertility, death rate, internal migration, international migration, and age structure. It also examines other factors such as marriage and family structure, and employment and education. Furthermore, the publication provides a discussion of the relationship between population growth and economic development from both a neo-Malthusian and Structuralist view. Finally, the paper considers the region's current population policies and future population prospects. From 1950-65, annual population growth averaged 2.8%, which decreased moderately to 2.4% from 1965-85. The report identified 3 population growth patterns in the region: 1) countries which experienced early and gradual declines in birth and death rates and generally lower population growth rates (the group includes Argentina, Cuba, Uruguay, with Chile and Panama also closely fitting the description); 2) countries which underwent rapid declines in birth rate during the 1950s and which began experiencing declines in the birth rate after 1960 (Brazil, Colombia, Costa Rica, the Dominican Republic, Mexico, Paraguay, and Venezuela, with Ecuador and Peru as borderline cases); and 3) countries which didn't begin to experience declines in mortality rates until relatively late and which lag behind in fertility declines (Bolivia, Haiti, El Salvador, Guatemala, Honduras, and Nicaragua). Although population growth has slowed and will continue to fall, UN projections do not expect the population to stabilize until late in the 21st Century.^ieng

Some aspects of socio-economic determinants of mortality in tropical Africa.

PIP: Measurements of mortality levels and trends continue to be inadequate in Africa, largely because of the lack of reliable and adequate information on deaths. A series of estimates depicting mortality levels and trends has been prepared by demographers, different kinds of data and employing different estimation procedures, but knowledge of the "true" structure of mortality in tropical Africa is virtually nonexistent. Because of these problems only a "bird's eye view" of the prevailing situation in tropical Africa is presented. The discussion -- directed to mortality by sex and age, by residence, and by cause -- is based on secondary and fragmentary data. Socioeconomic and cultural determinants of mortality are also examined. Available information on male and female mortality indicates that the death rates for males are higher than they are for females. Early childhood mortality (1-4 years) in tropical Africa is relatively high compared with the other age groups, including infants. Mortality differentials have been noted among geographical and administrative units and subdivisions of populations within the various countries of tropical Africa. Also, urban dwellers enjoy a higher expectation of life at birth than do rural dwellers. Communicable diseases are the main killers in tropical Africa. Persistent poverty and malnutrition, poor housing, unhealthy conditions in the growing cities, nonexistence of health facilities in the rural areas, rapid population expansion, and low levels of education are among the factors impeding progress in reducing mortality in tropical Africa. The need exists to express development goals in terms of the progressive reduction and eventual elimination of malnutrition, disease, illiteracy, squalor, and inequalities. Future trends in mortality in tropical Africa may depend more than they have in the recent past on economic and social development.^ieng

Black America in the 1980s.

PIP: This Bulletin reviews recent demographic and socioeconomic trends in the US black population in order to assess changes in the status of blacks relative to whites since publication of the 1962 edition of Gunnar Myrdal's 1944 classic "An American Dilemma." Blacks numbered 26.5 million in 1980, 11.7% of the total population, with 85% residing in urban areas compared to 71% of whites. Some suburbanization is now occurring among blacks but the majority remain segregated in central cities. In the 1970s, more blacks moved into the South than moved out in a reversal of the historic pattern. Blacks have shared the baby bust since the mid-1960s but teenage and out-of-wedlock fertility remain much higher than for whites as well as overall fertility (2.3 compared to 1.8 births/woman in 1979). Black infant mortality is still double that of whites and life expectancy is 6 years shorter (68.3 vs. 74.4 years in 1979). Single parents (mostly mothers) with children now comprise 31% of black families compared to 10% for the general population. Divorce and separation have risen faster for blacks than whites. Many of these gaps are related to blacks' continuing socioeconomic disadvantages: median family income is 56% that of whites; the poverty rate is 3.5 times higher; unemployment is twice as high. Occupational status has improved for blacks and their educational attainment is now close to that of whites, but these gains may be slowed and income differentials unimproved if the current administration's reversal of socioeconomic policy remains unchanged. Blacks are also affected more than other groups by the recent surge in immigrants who compete directly for the low-level jobs on which many blacks must still rely. (author's).^ieng

U.S. population: where we are; where we're going.

This Bulletin reviews recent trends in the dynamics and character of the U.S. population, the outlook for the remainder of the 1980s, and prospects for longterm growth. Estimated at 232 million as of mid-1982, the U.S. population is currently growing at about 1% a year, one of the developed world's highest growth rates. Natural increase (births-deaths) still adds some 1.7 million people a year, despite the rapid postbaby boom fall in fertility to a near-record low rate of 1.9 births/woman in 1981. With increasing numbers of refugees, net legal immigration averaged 600,000/year in 1979-81 and the net inflow of illegal immigrants may now be 500,000 a year. Uncertainty over potentially large numbers of immigrants complicates projections of future U.S. population size. Currently, the U.S. death rate is at an alltime low. More than 1/2 the population now resides in the South and West. Rural areas and small towns grew faster than urban areas in the 1970s for the 1st time in over a century. Educational attainment is at an alltime high, as is labor force participation, due to increasing employment among women and the baby boom generation's arrival at working ages. The age composition of the population, with the bulge of the baby boom generation surrounded by the older "depression" generation born during the 1930s and the younger "baby bust" generation born since the end of the 1960s, presents special problems for U.S. society.

Environmental motivations for migration: population pressure, poverty, and deforestation in the Philippines.

"This paper uses a multinomial discrete choice model and data from the Philippines to examine migrant choice between alternative destinations. Travel costs and perceived opportunities at the upland frontier are more important than general (upland plus lowland) destination attributes that indicate more developed social infrastructure or greater expected welfare. For example, migration streams are larger to destinations where the public share of forestland and the road system are larger. These features also characterize regions of more rapid deforestation. Therefore, emigration policies must recognize their effects on deforestation at the frontier--and their anticipated indirect effects on downstream environments."

National-, regional- and urban-scale population deconcentration in West Germany.

"Internal migration patterns during the second half of the 1970s and the first half of the 1980s are evaluated at a regional scale intermediate to those utilized in previous core-to-periphery and urbanization-to-counterurbanization studies of West Germany. A spatial deconcentration of the West German population is evident in the form of redistribution down the metropolitan size hierarchy....A spatial deconcentration of manufacturing and service employment partially explains the net migration losses experienced by the Rhine-Ruhr and the Rhine-Main-Neckar [regions].... This study provides an alternative core-periphery delimitation scheme which can be applied to the metropolitan system in the western part of newly unified Germany."

An econometric model of internal migration and development: extensions and tests.

The author extends a previous work on migration in Italy "from 1958-1976 to 1958-1981, tests for the stability of the model and its coefficients, and uses the model for policy simulations and forecasting. The model performs as well over the extended sample period as over the original period and, even more important..., the model is found to be quite stable. This is remarkable in view of the economic turmoil that characterized the years by which the original sample period was extended."

Nested logit model and maximum quasi-likelihood method: a flexible methodology for analyzing interregional migration patterns.

"A flexible methodology for explaining interregional migration in terms of relevant socioeconomic variables is set forth in this paper. Concerned with setting observation against theory, it makes use of (1) the nested logit model as a theoretical substratum, and (2) the maximum quasi-likelihood method as a method for parameter estimation and statistical inference. Application to interprovincial migration data over a 22-year period (1961-1962 to 1982-1983) shows that, in Canada, migration does not appear to serve well as an equalizer of economic opportunities."

The migration function and the Todaro paradox.

"The purpose of this paper is to present a microeconomic foundation of the migration function and to discuss the impact of an increase in the job creation rate on migration and urban unemployment. Each rural worker must estimate his expected urban income on the basis of his own expected numbers of both newly created jobs and migrants during the coming period. Workers whose expected urban income is greater than the rural one decide to migrate, while those who estimate smaller urban income stay on." The geographical focus is on developing countries.

Calibrating longitudinal models of residential mobility and migration: an assessment of a non-parametric marginal likelihood approach.

"This paper discusses the problems of controlling for omitted variables in estimating the structural parameters of longitudinal models and focuses upon an assessment of a non-parametric marginal maximum likelihood approach suggested by the results of Laird.... The approach is shown to be statistically valid for a plausible discrete-time model of the incidence of residential or migration moves, at least for data in which no household moves in every time period. Empirical evaluation with two large [U.S.] datasets on residential mobility indicates that the approach is also computationally feasible and provides a promising alternative to more conventional methods for controlling for omitted variables."

Occupational change, employer change, internal migration, and earnings.

"In this paper I use microdata from the [U.S.] Panel Study of Income Dynamics to measure the financial returns to intercounty and interstate migration for individuals in a temporal framework accounting for gains that accrue over time.... To account for the indirect effects of migration on earnings, explanatory variables are created by interacting migration status with: (1) occupational change, (2) employer change and (3) changes in both occupation and employer. These interaction terms are then included in the earnings functions. Earnings are estimated for three years subsequent to the migration decision to account for the financial returns to migration accruing over time. Results indicate that, when estimating earnings, the use of a simple migration dummy variable will mask the indirect effects of migration on earnings."

The efficiency of interprovincial migration in Canada, 1961-1978.

PIP: A programming model is used to analyze the impact of the efficiency of migration flows on regional income disparities in Canada. A new method to measure such efficiency is presented in an attempt to show that occupations involving high-level skills and training have efficient migration patterns. The relationship between income differentials and internal migration is discussed.^ieng

Self-selection and intermunicipal migration in Canada.

"This paper investigates individual intermunicipal migration behaviour in Canada within the context of a human capital model that adjusts for the migrant's selectivity in computing expected income gains. In addition to the typical regional determinants of migration, housing and labour market characteristics are found to influence intermunicipal migration significantly, the effects differing with age. Structural coefficients remained more or less stable during the decade 1971-1981. It is shown that the failure to adjust income gains for selectivity bias results in an underestimation of the migration-impacts of income gains and municipal-specific factors."

Does migration arbitrage regional labor market differentials?

"This paper examines the determinants of regional migration [in the United States] in the 1980s using a place-to-place migration model in which migration flows depend upon the relative economic opportunities in the origin and destination regions. Using the results of the model, we then examine the potential role for migration in diffusing the economic pressures associated with disparate regional economic growth. Although the results reinforce the notion that divergent regional growth was an impetus to migration in the 1980s, estimates of the employment status of movers suggest that the true effects of migration on unemployment differentials may be quite small."

A theoretical and empirical evaluation and extension of the Todaro migration model.

"This paper postulates that it is theoretically and empirically preferable to base internal labor migration on the relative difference in rural-urban real income streams and rates of unemployment, taken as separate and independent variables, rather than on the difference in the expected real income streams as postulated by the very influential and often quoted Todaro model. The paper goes on to specify several important ways of extending the resulting migration model and improving its empirical performance." The analysis is based on Italian data.