Social science & medicine. Part D, Medical geography最新文献

Data for mortality from lung-bronchus cancer, gastric cancer and cancer of the large intestine and rectum, respectively, in males and for breast cancer in females, age group 15–64 years for both sexes, for the years 1970–1972 inclusive, and data on age-structure of local populations (1971 census) are used to calculate standardized mortality ratios (SMR) for the selected causes for 320 administrative areas in the British Isles. The SMRs indicate mortality experience after allowance is made for variations in the age structure of populations throughout the country. The SMRs are portrayed on a demographic map, which shows the distribution of mortality experience relative to the populations at risk in the different parts of the country. Marked spatial variations in mortality experience of each of the selected malignant neoplasms are revealed. The unequivocal quantitative relationship which epidemiologists have demonstrated between lung cancer experience and cigarette smoking does not explain the spatial disparities and urban affinities of mortality from that disease. In the case of gastric cancer, high risk areas are present in both urban and rural areas; the spatial pattern provides no support for the reported statistical association between gastric carcinoma and people of blood group A. The geographical pattern of elevated mortality from cancer of the large intestine and rectum does not lend support for the hypothesis that the carbohydrate rich diet of people living in less affluent parts of the country predisposes to tumours of this site. The marked spatial heterogeneity of female mortality from cancer of the breast suggests a variety of life-style and environmental associations. Geographical variations in mortality experience from the selected malignant neoplasms within the British Isles support the view that environmental factors—physical, biological, socio-cultural—are involved in their multifactorial aetiology.

In India, two parallel systems of medicine (modern and traditional—Ayurvedic, Siddha and Unani) exist. Very little is known about the way the two divergent approaches to healing operate side by side even in the same metropolitan settings. Even though overall trends may appear to be moving towards adoption of modern scientific therapy especially in urban areas, general observations indicate Indian systems of medicine and its practitioners are no way diminishing in size in serving some of the basic health needs of the people in Indian cities. However, very little is known about the reasons for the persistence of indigenous medical practices in the most expanding urban areas.

This paper presents some of the practical aspects of traditional Indian medical practices from data and information obtained from the results of field questionnaires administered to private registered practitioners of indigenous medicine in the city of Madras in the state of Tamil Nadu, India. The analysis is primarily concerned with the actual distribution and socio-economic characteristics of the practitioners rather than theoretical or developmental ideals.

Only a mixed assessment of medical practices can be presented. The survey indicates that all the three systems of medicine seem to provide fairly satisfactory solutions for common ailments. The practical, survival and prestige values of many of the practitioners in the informal sector of the city are still high in spite of competition from modern practitioners. Their services freely cut across all socio-economic groups in the city. On the other hand obstacles such as lack of standardized training and qualifications of the practitioners, slow adoption of modern scientific and technical methods of practice and research, still stand in their way of progress and advancements.

The IMPs (Indigenous Medical Practitioners) still represent a vast underutilized human resource outside the official health services for want of strong government commitment, financial support and comprehensive programmes to improve the quality of their services as well as to facilitate their participation and integration in health plans at all levels. Collaboration and cooperation have hardly begun between the two systems. The bargaining power of the IMPs is still weak. They also operate in isolation and they are reluctant to cooperate in integration of the two systems which may threaten their individual cultural heritage characteristics and force them to occupy not only a subordinate role but lose their independence. They prefer to see a dual system of medicine promoted rather than an integrated system.

The medical geography of Nigeria in the twentieth century cannot well be written without a full chapter devoted to the cholera epidemics of 1971. Though some medical men had written on the clinical and epidemiological aspects of these epidemics, very little is still known about the prevalence and distribution of the dreadful disease. This paper thus concerns itself with the distribution characteristics of this cholera spread in the largest indigenous city in the country, i.e. Ibadan.

The first stage of the analysis (i.e. the temporal analyses) reveals that the cholera epidemic in Ibadan city in 1971 conformed to the classical epidemic curve of a positively skewed normal distribution with one marked and steep modal peak. The finding is in conformity with that postulated theoretically and empirically discovered in the past. The modal peak is also observed to be asymmetrical thus conforming also to existing theory.

In terms of the cholera distribution characteristics, the epidemic had two waves of diffusion. The first wave covered weeks 1–26 of 1971, while the second wave coincided with the later part of the year. The first cholera epidemic wave had a strongly peaked and very positively skewed curve in both time and the frequency domains; thus the wave could be said to have an abrupt onset and a very rapid decline. The second wave on the other hand was platykurtic and relatively normal in distribution.

During the first epidemic wave, areas of earliest infection (i.e. the traditional core of the city) has a faster rate of diffusion than areas of later diffusion but during that second wave the peripheral areas (areas of later diffusion) were more affected in term of intensity of infection than the core area. The diffusion rate was faster also during the first wave than during the second wave, thus the second wave was of a less severe import than the first.

Though prediction of the second wave from the first wave was not possible, some vestiges of a “time” with “time” relationship of the first and the second wave was noticed.

The annual variation rates were sought using the maximum likelihood method based on a Poisson model for the purpose of observing trends in deaths due to malignant neoplasms during the period 1954–1975 in 23 countries as an approach towards elucidation of the carcinogenic factors involved. For all cancers, males in 22 countries showed significant increases while for females 6 countries showed significant increases and 14 countries showed significant decreases. Sites in which the majority of countries demonstrated significant increases in rates were intestines, lungs, prostate and leukaemia in males and intestines, lungs and breast in females. On the other hand, significant decreases in rates observed in males were stomach and in females stomach and uterus.

The increases and decreases in annual variation rates for the various cancers are introduced in the hope that they will serve as fundamental data when studying the characteristics external risk factors of the respective countries concerned.

In geographic epidemiology, distribution of the categorized mortality or morbidity rates are visualized on a map. either based on actual land area or adjusted for the population density. Irrespective of the map used, visual study per se by no means indicates the statistical significance of the observed clusters, i.e. whether the geographic aggregations could occur by chance alone. We have developed an approach for assessing the deviation from chance expectation of the geographic pattern actually observed on a map and have described it in this paper.

A simple chi-square test is proposed, and the parameters required for the test are (1) total number of areas. (2) numbers of subareas for each mortality or morbidity category. (3) total number of geographically adjacent areas, and (4) observed numbers of adjacent areas having concordant category pairs.

When the test was applied to the geographic distribution of esophageal cancer mortality by city and county in Japan (1969–1971). the areas with high mortality were significantly clustered in both sexes, and those with low mortality in males.

There were no significant aggregations for breast cancer, though the areas with high mortality seemed distributed mainly in the northern half of the mainland. Japan. For uterus cancer low mortality showed significant clusters, and total geographic pattern was highly significant.

The validity of the proposed simple chi-square test of significance was substantiated by a Monte Carlo approach, which was derived analytically as a special case of Knox's test for space-time clustering.

The science of Medical Geography permits the delineation of maps of illness using different scales to compare the factors of incidence of a disease. The identification of differences in risk according to population and region facilitates the elaboration of ecological hypotheses relative to the cause of disease. Cancer in humans is an illness of high frequency in our society. According to the most recent Canadian statistics it is in Quebec that the risk of being a cancer victim is the greatest in this country. During the years 1970–1972 Quebec males registered the highest frequency for the ensemble of seats of cancer, while Quebec females ranked directly after those of Nova Scotia. In addition, cancer remains one of the illnesses where environmental agents may exercise a determinant role. Certain experts consider that the direct or indirect dependence upon environmental factors applies in 80 to 90% of cancer cases.

To establish the geographic location of cancers in Quebec we have used figures supplied by Statistics Canada for census regions (R.R.I of Quebec. We have taken the number of new cases of malignant tumors observed during the year for each type of tumor figuring in the international classification of illnesses for a period of 5 years that is from 1970–1975. These figures indicate the rates of incidence of a specific cancer observed during the period in question and allow us to calculate the ratio of incidence standardized according to age (SIR) in order to analyze the incidence of malignant tumors in the various census regions.

The objective of this study was to discover the possible relation between the quality of drinking water and cancer. More particularly, we think that certain cancers are more prevalent in regions where the water is considered “soft”. To establish this relation we grouped the R.R. by sites of cancer in two groups: one where the SIR was high and one where the SIR was low. The R.R. of less than 10 cases of cancer per year were eliminated. We then compared the R.R. of high and low rates of incidence according to physicochemical parameters of drinking water as per 1974–1976 observational data. The analysis of correlations and multiple regression were used to evaluate the significant associations.

In order to study environmental factors related to the incidence of lung cancer (ICD 162), sex-specific standardized mortality ratios (SMRs) of lung cancer were calculated for 3297 basic autonomic units (91 wards, 629 cities, 1958 towns and 619 villages) in Japan, based upon the vital statistics for six years, 1964–1974. and sex- and age-specific population of each area in 1970. The SMRs were classified into five categories and depicted on a map for each sex.

These maps show that areas with high SMR of lung cancer tended to cluster in the highly urbanized and industrialized districts. However, some of these areas with high SMR were also widely scattered throughout Japan.

In an effort to study this geographical difference in areal mortality from lung cancer, analyses were carried out in two ways. First, the areas with high or low SMR were selected to examine the relationship between lung cancer mortality by sex and environmental characteristics; the high SMR group consists of the areas with SMR 120 or more and significantly higher than the average of Japan (112 areas for male and 74 for female), while the low SMR group of those with SMR less than 80 and significantly lower than the average (155 areas for male and 50 for female). Second, all of the areas were divided into two groups according to the existence of some environmental characteristics and the magnitude of SMRs were compared between these groups.

The results from the first analysis are as follows:

• 1.

  1. High SMR group in both sexes has significantly more air-polluted areas than low SMR group.

• 2.

  2. High SMR group of male but not female has significantly higher percentages of areas with metal refineries, steam power plants, oil refineries and coal mines than low SMR group.

• 3.

  3. Percentage of areas with metal mines in high SMR group is higher than that in low SMR group for both sexes, although the differences are not statistically significant.

The results from the second analysis are as follows:

• 1.

  1. Among the four categories of urbanization represented by ward, city, town and village, the more urbanized categories such as ward and city have the higher SMR of lung cancer.

• 2.

  2. The SMR is higher in the areas along the sea coast than in those without the coast regardless of the urbanization. The SMR is higher especially in male in the areas with fishing ports than in the other coastal areas without the ports.

• 3.

  3. The SMRs for both sexes are higher in the areas with steam power plants, coal mines or lignite mines than in the areas without these industries regardless of the urbanization.

Medical Geography is a recent development in Canada. Although a few individuals have conducted medical geographic research in the past there was no sustained commitment to either such research or to teach courses on the subject. The current growth can be attributed to several factors.

Among these factors is an increasing number of Canadian geographers with Third World experience, the restating of relevancy concerns as applied to research and the recent development of medical geography in the United States, Britain and France. In 1976 Thouez organized the Canadian Working Group in Medical Geography as a sub-section of the Canadian Association of Geographers. In the previous year he had initiated the first graduate course in Medical Geography in Canada at the French language University of Sherbrooke. At Windsor Innes succeeded in funding a 6 month visiting professorship in 1977 for Howe of Great Britain and launched a semester undergraduate course. Starting in 1974 Barrett at York had devoted increasingly larger sections of his course on population geography to medical geography. In 1977–1978 he offered for the first time in Canada a full-year undergraduate course in medical geography. Meanwhile at Queen's, Tinline had been continuing his long-term commitment to disease research for the Ontario government and in 1977 he offered a half-course in medical geography.

Increasingly papers on medical geography were offered at the regional and national meetings of the Canadian Association of Geographers with at least one special session on medical geography from 1976 to the present.

The current status of medical geography in Canada is that of a small but dedicated group. Student response has been very encouraging and is growing, although one would not see it as a major subdiscipline of the field.

A tremendous challenge confronts medical geographers as governments try to reduce health costs and improve quality of life. The spatial problems and the mismatch between humans and their environment exist. The unanswered question is to what degree will Canadian medical geographers be involved in the analysis of these problems?