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PubMed2002

Evaluation of the age-adjusted incidence of hip fractures between urban and rural areas: the difference is not related to the prevalence of institutions for the elderly.

As many as 40% of hip fractures occur in institutions for the elderly. Several studies have demonstrated a higher age-adjusted incidence of hip fractures in urban areas compared with rural areas. To assess whether this difference could be due to a preferential location of institutions for the elderly in urban areas, we compared the incidence of hip fractures over a 5-year period in urban versus rural areas, as defined according to the population density (urban > 15 inhabitants/ha2). We then determined the age-adjusted incidence of hip fractures in institutional-dwelling elderly and home-dwelling elderly. Hip fracture incidence was 100.0/100,000 (150.5 in women and 43.8 in men) in urban areas, and 71.0/100,000 (107.2 in women and 32.8 in men) in rural areas (p<0.001). When only those patients living in their own homes were analyzed, the incidence was 66.7/100000 (94.6 in women and 35.7 in men) in urban regions and 36.8/100,000 (49.6 in women and 23.4 in men) in rural areas (p<0.001), a difference of even greater magnitude than when both home-dwelling and institutional-dwelling residents were considered together. In a logistic regression model including age class, gender, urban or rural areas and institutionalization for inhabitants 65 years of age and older, urban residents have a 31% significantly (p<0.001) higher incidence of hip fracture compared with rural residents; women have a 79% significantly (p<0.001) higher incidence of hip fracture compared with men; and institutional-dwelling elderly have a 351% significantly (p<0.001) higher incidence of hip fracture compared with home-dwelling elderly. These results confirm the existence of a higher age-adjusted incidence of hip fractures in urban compared with rural areas. Since this difference is increased when patients living at home were analyzed separately, it indicates that the difference between urban and rural areas is not due to a preferential urban location of institutions for the elderly.

Age Distribution↗

PubMed2006

Assessing impact of urbanization on river water quality in the Pearl River Delta Economic Zone, China.

The Pearl River Delta Economic Zone is one of the most developed regions in China. It has been undergoing a rapid urbanization since the reformation and opening of China in 1978. This process plays a significant impact on the urban environment, particularly river water quality. The main goal of this present study is to assess the impact of urban activities especially urbanization on river water quality for the study area. Some Landsat TM images from 2000 were used to map the areas for different pollution levels of urban river sections for the study area. In addition, an improved equalized synthetic pollution index method was utilized to assess the field analytical results. The results indicate that there is a positive correlation between the rapidity of urbanization and the pollution levels of urban river water. Compared to the rural river water, urban river water was polluted more seriously. During the urban development process, urbanization and urban activities had a significant negative impact on the river water quality.

China↗

PubMed2005

Is the urban excess in lung cancer in Scotland explained by patterns of smoking?

Numerous studies have shown that lung cancer rates are higher in urban than rural areas, controlling for differences in age and sex profiles. One explanation is that smoking rates are higher in urban areas, although it is not clear whether the variations in smoking behaviour fully account for the observed urban/rural gradient in lung cancer incidence. Indeed, some studies have demonstrated an excess of cases in urban areas, even controlling for smoking behaviour. However, previous studies have been hampered by the lack of small-area smoking estimates which are required if urban/rural variations are to be examined reliably. This paper considers whether there is an urban excess in lung cancer incidence in Scotland, a country with particularly high rates of the disease, for the period 1988-1991. First, we examine whether an urban excess exists in Scotland using Poisson probabilities and a cluster detection technique. Second, regression analysis was then used to test whether any urban excess in lung cancer incidence remained once smoking behaviour was controlled for, using smoking estimates calculated for small areas throughout Scotland. The results demonstrate that the rates of lung cancer were higher in urban areas and that all the significant clusters of cases of lung cancer were located in the large urban centres of Scotland. Smoking behaviour did account for much of this urban excess in lung cancer, although it did not explain the entire effect. These results suggest that there are urban effects that influence the incidence of lung cancer that are not explained entirely by smoking behaviour. Possible explanations include the variations in exposure to air pollution, occupational differences and the legacy of selective migration between urban and rural areas.

Adult↗

PubMed1997

Serum total and fractionated cholesterol distribution and prevalence of hypercholesterolemia in urban and rural communities in Saudi Arabia.

Hypercholesterolemia is recognized as an independent risk factor for cardiovascular diseases. Data on serum total cholesterol concentration distribution from Saudi Arabia are scarce. We have conducted a cross sectional, national, epidemiological randomized household survey to study the distribution of serum total cholesterol (TCC), low density lipoprotein (LDL) and high density lipoprotein (HDL) concentrations, total cholesterol/high density lipoprotein (CH/HDL) ratio and prevalence of hypercholesterolemia (HC) among subjects aged 25-64 years in urban and rural communities of Saudi Arabia. The sample was 2924 Saudi subjects which was adjusted in accordance with the national population distribution with respect to age, gender, regional and residency, urban vs. rural population distribution. Height and weight were measured with calculation of body mass index (BMI). Blood samples were drawn and assayed for total cholesterol, triglyceride, high density lipoprotein concentration and calculation of low density lipoprotein concentration. The mean of BMI was significantly higher among female subjects and significantly higher among urban subjects. The prevalence of obesity was higher among female subjects and higher, however, not significant, among urban subjects. Mean serum TCC was higher among rural subjects. Mean serum LDL concentration was higher among female subjects and higher among urban subjects. Mean serum HDL concentration was lower among female subjects and lower among urban subjects. Mean CH/HDL ratio was higher among female subjects and higher for urban subjects. Female and male subjects living in rural communities had the highest and lowest percentages of subjects with high concentrations of LDL, respectively. Female and male subjects, living in rural communities had the highest and lowest percentages of subjects with low concentration of HDL, respectively. Male and female subjects living in rural communities had the highest and lowest percentages of studied subjects with a high CH/HDL ratio. The age-adjusted prevalence of HC (5.2-6.2 mmol/l) was equal among all the four groups. The prevalence of HC (> 6.2 mmol/l) was significantly higher among rural male subjects, compared with their counterparts in urban areas, while it was equal among female subjects. There was an increase in age-specific prevalence of HC (> 6.2 mmol/l) with maximum prevalence achieved at an age of 56-64 years for urban subjects, while it was achieved a decade earlier for rural subjects. The prevalence of HC, in general, was higher among rural male and urban female subjects. In conclusion, among Saudi subjects, means of total, fractionated cholesterol concentration, CH/HDL ratio > 6.5 and prevalence of obesity were higher among urban female subjects. The prevalence of HC, whether > 5.2 or > 6.2 mmol/l was higher among rural subjects. The difference, however, reached significance among female subjects. There is a need to study the possible underlying factors for the increase in prevalence of HC among rural subjects with special emphasis on the food components and nutritional habits of rural communities in Saudi Arabia. There is also a need to establish a control program throughout the country with the aim of halting the upward trend in incidence of CVD through control of modifiable risk factor such as obesity and hypercholesterolemia.

Adult↗

PubMedDate not supplied

Effects of air pollution on children's pulmonary function in urban and suburban areas of Wuhan, People's Republic of China.

In May and June of 1988, the spirometric lung function of 604 children, who were aged 7-13 y and who were free of chronic respiratory conditions, was measured in the urban core and a suburb of Wuhan, China. During 1981-1988, ambient total suspended particulate (TSP) levels averaged 481 micrograms/m3 in the urban core and 167 micrograms/m3 in the suburb. In 1988, TSP levels, measured within 500 m of the children's homes, averaged 251 micrograms/m3 in the urban core and 110 micrograms/m3 in the suburb. Levels of sulfur dioxide and nitrogen oxides were also higher in the urban core. Proportions of families who burned coal and gas domestically were similar in both areas. In linear and logarithmic regression models, height was a stronger determinant of forced vital capacity and forced expiratory volume in 1 s than was age or weight. In linear models, the proportion of variance explained by height (R-squared) ranged from 0.54 for urban females' forced expiratory volume in 1 s to 0.77 for suburban males and females. Both forced vital capacity and forced expiratory volume in 1 s were consistently lower in urban than suburban children. The average forced vital capacity and forced expiratory volume in 1 s in children 132-144 cm tall were 6.7% and 3.8% lower, respectively, in the urban core than the suburb; suburban-urban differences increased with height. Suburban-urban differences in slopes of lung function growth curves were statistically significant for forced vital capacity but not for forced expiratory volume in 1 s. Rates of clinical upper respiratory irritation were also generally elevated in urban children. These results strongly suggest that urban ambient air pollution exposure in China contributes to retardation in the growth of children's lung function. Confirmatory longitudinal studies are in progress in Wuhan and three other Chinese cities.

Adolescent↗

PubMed2003

The inequality of maternal health care in urban sub-Saharan Africa in the 1990s.

Numerous studies document the disadvantage in child health of the urban poor in African cities. This study uses Demographic and Health Survey data from 23 countries in sub-Saharan Africa to examine whether the urban poor experience comparable disadvantages in maternal health care. The results show that, although on average the urban poor receive better antenatal and delivery care than rural residents, the care of the urban poor is worse than that of the urban non-poor. This suggests that the urban bias in the allocation of health services in Africa does not benefit the urban poor as much as the non-poor. Multilevel analyses reveal significant variations in maternal health in urban areas across countries of sub-Saharan Africa. The dis-advantage of the urban poor is more pronounced in countries where maternal health care is relatively good. In these countries the urban poor tend to be even worse off than rural residents, suggesting that the urban poor have benefited least from improvements in maternal health care.

Africa South of the Sahara↗

PubMed2001

Urban zoonoses caused by Bartonella, Coxiella, Ehrlichia, and Rickettsia species.

The last half of the 20th Century witnessed an increase in the occurrence and recognition of urban zoonoses caused by members of the genera Bartonella, Coxiella, Ehrlichia, and Rickettsia, all traditionally considered to be members of the family Rickettsiaceae. In recent years, new human pathogens (Bartonella elizabethae, Bartonella henselae, and Rickettsia felis) have been recognized in urban environments. Other newly recognized pathogens (Ehrlichia chaffeensis and Ehrlichia phagocytophila in the United States) have sylvan zoonotic cycles but are present in urban areas because their vertebrate hosts and associated ectoparasitic arthropod vectors are able to survive in cities. Still other agents, which were primarily of historical importance (Bartonella quintana) or have not traditionally been associated with urban environments (Rickettsia rickettsii), have been recognized as causes of human disease in urban areas. Some diseases that have traditionally been associated with urban environments, such as rickettsialpox (caused by Rickettsia akari) and murine typhus (caused by Rickettsia typhi), still occur in large cities at low or undetermined frequencies and often go undetected, despite the availability of effective measures to diagnose and control them. In addition, alternate transmission cycles have been discovered for Coxiella burnetii, Rickettsia prowazekii, and R. typhi that differ substantially from their established, classic cycles, indicating that the epidemiology of these agents is more complex than originally thought and may be changing. Factors leading to an increase in the incidence of illnesses caused by these bacteria in urban areas include societal changes as well as intrinsic components of the natural history of these organisms that favor their survival in cities. Transovarial and transstadial transmission of many of the agents in their arthropod hosts contributes to the highly focal nature of many of the diseases they cause by allowing the pathogens to persist in areas during adverse times when vertebrate amplifying hosts may be scarce or absent. Domesticated animals (primarily cats, dogs, and livestock) or commensal rodents [primarily Norway rats (Rattus norvegicus) and house mice (Mus musculus)] can serve as vertebrate amplifying hosts and bring these agents and their ectoparasitic arthropod vectors into direct association with humans and help maintain transmission cycles in densely populated urban areas. The reasons for the increase in these urban zoonoses are complex. Increasing population density worldwide, shifts in populations from rural areas to cities, increased domestic and international mobility, an increase in homelessness, the decline of inner-city neighborhoods, and an increase in the population of immunosuppressed individuals all contribute to the emergence and recognition of human diseases caused by these groups of agents. Due to the focal nature of infections in urban areas, control or prevention of these diseases is possible. Increased physician awareness and public health surveillance support will be required to detect and treat existing urban infections caused by these agents, to determine the disease burden caused by them, to design and implement control programs to combat and prevent their spread, and to recognize emerging or resurging infections caused by members of these genera as they occur.

Animals↗

PubMed2005

Suicide risk in relation to level of urbanicity--a population-based linkage study.

BACKGROUND: The extent to which the high suicide rate in urban areas is influenced by exposures to risk factors for suicide other than urbanicity remains unknown. This population-based study aims to investigate suicide risk in relation to the level of urbanicity in the context of other factors, and to study the risk variation in a sex, age, and calendar year perspective. METHODS: The study is a nested case-control study comprising 21 169 suicides and 423 128 population controls matched for age and sex. Personal data on place of residence, socioeconomic status and psychiatric history were retrieved from various Danish longitudinal registers. Data were analysed with conditional logistic regression. RESULTS: This study confirms that people living in more urbanized areas are at a higher risk of suicide than their counterparts in less urbanized areas. However, this excess risk is largely eliminated when adjusted for personal marital, income, and ethnic differences; it is even reversed when further adjusted for psychiatric status. Moreover, the impact of urbanicity on suicide risk differs significantly by sex and across age. Urban living reduces suicide risk significantly among men, especially young men, but increases the risk among women, especially women aged 24-35 or >65 years. In addition, during 1981-1997, the suicide risk associated with urbanicity remained rather constant among women, whereas it dropped significantly among men, a trend that seemingly gained strength during the last part of this period. CONCLUSIONS: Suicide risk associated with urbanicity varies significantly by sex and age groups and recent years have seen a decline in the urban-rural disparities among men. The increased risk in urban areas can largely be explained by the effects of marital status, ethnics, income, and psychiatric status.

Adolescent↗

PubMedDate not supplied

Prevalence of asthma in urban and rural children in Tamil Nadu.

BACKGROUND: There are very few community-based studies on the prevalence of asthma in Indian children. We aimed to estimate the prevalence of asthma in children under 12 years of age and to study possible differences in the prevalence of childhood asthma in urban and rural areas of Tamil Nadu. METHODS: A total of 584 children from Chennai and 271 children from 25 villages around Chennai formed the urban and rural groups, respectively. From November 1999 to February 2000, data were collected using a simplified version of the ISAAC questionnaire, which was administered by trained students. Symptoms suggestive of asthma or hyperreactive airways disease in children under 12 years of age were recorded from the selected urban and rural populations by questioning the parents. The results were analysed separately for children 0-5 and 6-12 years of age. RESULTS: Of the 855 children studied, the overall prevalence of breathing difficulty (including asthma) was 18% and the prevalence of 'diagnosed' asthma was 5%. Twenty-two per cent of urban and 9% of rural children 6-12 years of age reported breathing difficulty 'at any time in the past' (p < 0.01). A significantly higher proportion of 6-12-year-old urban children also reported nocturnal drycough (28.4% v. 18.7%, p < 0.05). Urban children reported recent wheeze more often than rural children (92% v. 77%, p = 0.01). CONCLUSIONS: Symptoms suggestive of asthma were present in 18% of children under 12 years of age. Though the prevalence of diagnosed childhood asthma was about 5% in both urban and rural areas, the prevalence of 'breathing difficulty' and nocturnal cough was significantly higher among urban children in the age group of 6-12 years. Children living in urban areas also reported 'recent wheeze' more often than rural children. Our data suggest that the actual prevalence of asthma and other 'wheezy' illnesses may be higher than that previously documented. Further studies are needed to confirm the difference in prevalence between urban and rural children and also to identify possible causes that could account for the higher urban prevalence of asthma in Tamil Nadu.

Asthma↗

PubMed2004

Remote sensing of the urban heat island and its changes in Xiamen City of SE China.

World-wide urbanization has significantly modified the landscape, which has important climatic implications across all scales due to the simultaneous removal of natural land cover and introduction of urban materials. This resulted in a phenomenon known as an urban heat island (UHI). A study on the UHI in Xiamen of China was carried out using remote sensing technology. Satellite thermal infrared images were used to determine surface radiant temperatures. Thermal remote sensing data were obtained from band 6 of two Landsat TM/ETM+ images of 1989 and 2000 to observe the UHI changes over 11-year period. The thermal infrared bands were processed through several image enhancement technologies. This generated two 3-dimension-perspective images of Xiamen's urban heat island in 1989 and 2000, respectively, and revealed heat characteristics and spatial distribution features of the UHI. To find out the change of the UHI between 1989 and 2000, the two thermal images were first normalized and scaled to seven grades to reduce seasonal difference and then overlaid to produce a difference image by subtracting corresponding pixels. The difference image showed an evident development of the urban heat island in the 11 years. This change was due largely to the urban expansion with a consequent alteration in the ratio of sensible heat flux to latent heat flux. To quantitatively compare UHI, an index called Urban-Heat-Island Ratio Index (URI) was created. It can reveal the intensity of the UHI within the urban area. The calculation of the index was based on the ratio of UHI area to urban area. The greater the index, the more intense the UHI was. The calculation of the index for the Xiamen City indicated that the ratio of UHI area to urban area in 2000 was less than that in 1989. High temperatures in several areas in 1989 were reduced or just disappeared, such as those in old downtown area and Gulangyu Island. For the potential mitigation of the UHI in Xiamen, a long-term heat island reduction strategy of planting shade trees and using light-colored, highly reflective roof and paving materials should be included in the plans of the city planers, environmental managers and other decision-makers to improve the overall urban environment in the future.

China↗

PubMed2004

Ecological limitations on aquatic mosquito predator colonization in the urban environment.

Urban malaria cases are becoming common in Africa as more people move into cities and industrialization proceeds. While many species of Anopheles mosquitoes vector malaria in rural areas, only a few are found within cities. The success of anthropophilic species in cities, such as members of the An. gambiae complex, may be explained by limitations on colonization by predator species in urban environments. Habitats that are temporal or structurally simple have lower predator survivorship in a variety of ecosystems, but these have not been investigated previously in an urban area. Areas within and around the Kenyan coastal town of Malindi were previously sampled for the presence of standing water using a geographic sampling strategy with probability proportional to size sampling of planned well-drained, unplanned poorly-drained, planned poorly-drained, unplanned well-drained, and peri-urban locations. Standing aquatic habitats in these areas were reassessed. During monthly sampling, presence/absence of mosquitoes and predator taxa were noted, as were ecological habitat variables: structural complexity and presence of water. Lambda statistics were calculated to associate predator guilds, habitat types, location variables, and ecological variables. All predator guilds found in habitats were strongly associated with habitat type, as were the structural complexity and temporal nature of the habitats. Types of habitat were heterogeneously distributed throughout Malindi, with swimming pools as a common habitat type in planned urban areas and tire track pools a common habitat type in peri-urban areas of Malindi. Predator colonization of aquatic habitats in Malindi was strongly influenced by habitat type, and not associated with location characteristics. Ecological variables were affected by the type of habitats, which are co-associated with planning and drainage in Malindi. While habitat types are distributed heterogeneously within Malindi, habitats with low predation pressure are available for mosquito colonization in both urban and peri-urban areas. The temporal, peri-urban tire track pools and the structural simplicity of urban swimming pools may discourage predator colonization, thereby increasing the probability of malaria vectors in these areas of Malindi. Future studies should evaluate habitats for use in malaria surveillance and experimentally test the effects of structural complexity and temporal nature of urban habitats on the densities of mosquito larvae and their aquatic predators.

Animals↗

PubMed2005

Understanding and addressing childhood immunization coverage in urban slums.

The National Population Policy (2000) aims at complete protection of all children against vaccine preventable diseases by 2010. Urban poor, many residing in slums, comprise about one fourth of India's 285 million urban population. 60% of the children aged 12-23 months in urban India are fully immunized; coverage among urban poor children is a dismal 43%. The inter state variations of immunization coverage in urban areas, reveals a service coverage gap which calls for a rethink on resource allocation and strengthening processes to improve immunization coverage amongst urban poor. Debilitating environmental conditions and high population density in slums expedite disease transmission. Comparisons of urban rural disease incidence indicate a particular urban risk for vaccine preventable diseases. This paper attempts to understand the current scenario and challenges in improving immunization coverage in urban slums; immunization being one of the most successful public health interventions of the past century. It also discusses possible mechanisms for effectively reaching the often left out urban poor. Coordinated activities by the multitude of providers, accurate information based outreach, effective monitoring and community enablement to demand quality services are critical for improving utilization of immunization services by a heterogeneous urban poor population.

Child↗

PubMed1990

Parasitic diseases and urban development.

The distribution and epidemiology of parasitic diseases in both urban and periurban areas of endemic countries have been changing as development progresses. The following different scenarios involving Chagas disease, lymphatic filariasis, leishmaniasis and schistosomiasis are discussed: (1) infected persons entering nonendemic urban areas without vectors; (2) infected persons entering nonendemic urban areas with vectors; (3) infected persons entering endemic urban areas; (4) non-infected persons entering endemic urban areas; (5) urbanization or domestication of natural zoonotic foci; and (6) vectors entering nonendemic urban areas. Cultural and social habits from the rural areas, such as type of house construction and domestic water usage, are adopted by migrants to urban areas and increase the risk of disease transmission which adversely affects employment in urban populations. As the urban health services must deal with the rise in parasitic diseases, appropriate control strategies for the urban setting must be developed and implemented.

Animals↗

PubMedDate not supplied

Urban AHECs: a comparison with rural AHECs.

The first generation of projects in the Federal Area Health Education Center (AHEC) Program was funded in 1972. Those AHEC projects, located in predominantly rural areas, focused on problems that resulted from the geographic maldistribution of health professionals, especially primary care physicians. Education programs for health professionals, students, and practitioners were used to influence the geographic distribution of health professionals and to improve access to and quality of health care for underserved populations. In 1976, the Congress redrafted the law authorizing the expenditure of funds for AHECs and emphasized that improving access to health care in urban underserved areas also was to be addressed by the program. During the early years of urban AHEC development, it was not clear which lessons learned from rural AHEC experiences could be applied to urban communities and what would be the best focus for AHEC activities in the complex urban environment. Some said that urban areas were so different from rural areas--in economic, racial, and cultural terms and in the subtlety of barriers to health care--as to make the rural AHEC experience largely irrelevant. Others maintained that basic AHEC principles could be applied, regardless of setting, with changes only in tactics to address the problems of the urban inner city. Now that 18 of the total 53 AHECs nationally are urban, and a decade of experience in developing them has been accumulated, it is appropriate to compare the types of educational interventions supported by AHECs in urban and rural environments and the relative priorities of such programs. In this report we examine the experiences of the California AHEC System, which includes 17 urban and rural centers and the 9 medical schools with which they are affiliated. Although the AHEC Program concept was found to be equally applicable to both urban and rural settings, significant differences in implementation were noted. Those differences were evidenced both by relative budgets,such as the large expenditures for undergraduate medical education in urban areas and for nursing in rural areas, and by subtler differences in the types of programs developed within budget categories

Area Health Education Centers↗

PubMed1994

Immunization in urban areas: issues and strategies.

In the past, immunization programmes have focused primarily on rural areas. However, with the recognition of the increasing numbers of urban poor, it is timely to review urban immunization activities. This update addresses two questions: Is there any need to be concerned about urban immunization and, if so, is more of the same kind of rural EPI activity needed or are there specific urban issues that need specific urban strategies? Vaccine-preventable diseases have specific urban patterns that require efficacious vaccines for younger children, higher target coverage levels, and particular focus to ensure national and global eradication of poliomyelitis. Although aggregate coverage levels are higher in urban than rural areas, gaps are masked since capital cities are better covered than other urban areas and the coverage in the poorest slum and periurban areas within cities is as bad as or worse than that in rural areas. Difficult access to immunization services in terms of distance, costs, and time can still be the main barrier in some parts of the city. Mobilization and motivation strategies in urban areas should make use of the mass media and workplace networks as well as the traditional word-of-mouth strategies. Use of community health workers has been successful in some urban settings. Management issues concern integration of the needs of the poor into a coherent city health plan, coordination of different health providers, and clear lines of responsibility for addressing the needs of new, urbanizing areas.

Child↗

PubMed1986

The growth of urbanization in Ethiopia, 1966-1984.

"This paper studies the growth and dynamics of urbanization in Ethiopia during the period 1966-1984. Despite its very low level of urbanization (10.6%), Ethiopia experienced rapid urban population growth of 4.8% per annum over the period. The urban growth was more rapid at the beginning (1966-70 = 6.6%) then slowed down to 4.23% in 1970-1984. There is highly uneven regional distribution of urbanization with the core urban region accommodating close to half the urban population; within regions, the majority of the urban population is concentrated in one or very few large urban areas." Data are from the preliminary results of the 1984 census, the two rounds of urban National Sample Surveys, and the Manpower and Housing Survey.

Africa↗

PubMedDate not supplied

[An approach to food consumption in an urban environment. The case of west Africa].

West Africa has undergone rapid economic and political changes during the last 20 years. After the failure of economic policies implemented since independence, programs for structural adjustment have strongly influenced the economy. Food problems affect each country differently. The Sahel has experienced food shortages and starvation whereas in forested countries the food supply has remained stable. Nevertheless, food policies have not succeeded in contributing to urban and rural development. The rate of urbanization in west Africa is generally low but the rate of urban population growth is particularly high, much more than the growth rates of industry and infrastructure. Although metropolitan areas are affected by poverty, they offer more hope and opportunities than rural areas. Urban markets have expanded and diversified as social differences have also increased and contributed to changes in consumption structure. Urban growth has contributed to the increase of imported food: this is indicated by both the strong dependency and the change of food habits towards western food patterns. Recently however, west African urban dwellers are still preferring local items if they are affordable. When imported products are used, they are integrated within a stable meal plan consisting of a single dish with a base and a sauce, which is typical of African food preparation. Surveys of consumption-budgets are still only available on a national scale. These can provide accurate information about food consumption patterns of families, particularly for significant trends. However, they do not provide information about the dynamics of food consumption, neither for urban areas or the individual. Now a significant proportion of individual food consumption occurs outside of the home, mainly with food provided by street vendors. This new consumption habit is a response to the urban food crisis. Consumption of street-vendor-food comprises one component but this cannot be dissociated from in-home food consumption. Despite the growing importance of street-vendor food consumption, it has still not been adequately documented. Theoretically, food consumption is an evolving concept. Single disciplines, such as economics or nutrition, first studied food consumption. More recently, social sciences developed new approaches with various interpretations, which were sometimes contradictory. The evolution of urban food consumption and the numerous related problems support the approach proposed by some authors suggesting a mixed analysis integrating both economics and cultural factors. Operationally, a global and dynamic approach to food styles must consider urban heterogeneity and diversity of situations. For example, food consumption by people maintaining their in-home food habits shows the pertinence of studies focusing on individuals. Therefore, the food course concept may be a useful method for the study of food consumption.

Africa, Western↗

PubMed2006

Songbird abundance and parasitism differ between urban and rural shrublands.

Many studies have examined differences in avian community composition between urban and rural habitats, but few, if any, have looked at nesting success of urban shrubland birds in a replicated fashion while controlling for habitat. We tested factors affecting nest survival, parasitism by the Brown-headed Cowbird (Molothrus ater), and species abundance in shrubland habitat in rural and urban landscapes. We found no support for our hypothesis that nest survival was lower in urban landscapes, but strong support for the hypothesis that survival increased with nest height. We found strong support for our hypothesis that cowbird parasitism was greater in urban than rural landscapes; parasitism in urban sites was at least twice that of rural sites. We found strong support for an urban landscape effect on abundance for several species; Northern Cardinal (Cardinalis cardinalis) and Brown-headed Cowbirds were more abundant in urban landscapes, whereas Field Sparrow (Spizella pusilla) and Blue-winged Warbler (Vermivora pinus) were more abundant in rural sites. There was support for lower abundances of Blue-gray Gnatcatcher (Polioptila caerulea) and Indigo Bunting (Passerina cyanea) with increased housing density. For six other species, edge and trail density or vegetation parameters best explained abundance. Lower abundances and greater parasitism in habitat patches in urban landscapes are evidence that, for some species, these urban landscapes do not fulfill the same role as comparable habitats in rural landscapes. Regional bird conservation planning and local habitat management in urban landscapes may need to consider these effects in efforts to sustain bird populations at regional and local scales.

Animals↗