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Title: Seasonal variation in tuberculosis
Author: Clayson, Christopher William
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1936
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Tuberculosis is a disease which exhibits well defined seasonal changes. The phenomena described above fall conveniently into three groups, namely, I. Clinical Observations on Local Lesions: II. Clinical Observations on Systemic Manifestations: and III. Seasonal Variation in Mortality. The conclusions gained from these investigations may be summarised as follows. I. SEASONAL VARIATION IN LOCAL LESIONS.- A.GLANDULAR TUBERCULOSIS: (1) The appearance of glandular swelling in tuberculosis of the lymphatic system occurs most commonly in the months of January and February, and least commonly in August and September; (2a) The formation of pus in these lesions is observable most frequently in March and April, and least frequently in August, September and October; (2b). Pulmonary Tuberculosis.- (i). Sputum is exptorated in greater quantities during March and April than at any other time of year, and conversely, is least abundant in June and July; (ii). There is no seasonal tendency in the incidence of pulmonary haemorrhage. II. SEASONAL VARIATION IN THE SYSTEMIC FACTOR: A. Body Temperature.- The body temperature in tuberculosis is very unstable, but the instability is especially marked in the months of February, March and April. This statement is true even of mild cases including adults of both sexes and children, but applies particularly to adult female patients; B. The Pulse Rate.- No seasonal variation is observable in the pulse rate of tuberculous patients; C. Body Weight: A well defined seasonal change occurs in the weight of tuberculous patients. A decline is noticeable during February, March and April, and is followed by an increase during the late autumn and early winter. In children this change is one of slow growth in the early part of the year, and rapid growth in the later part of the year It is suggested, however, that these variations are the expression (possibly exaggerated) of a normal tendency; D. The Tuberculin Reaction.- The response to tuberculin is probably more rapid during the spring than at other times of year; III. SEASONAL VARIATION IN MORTALITY: A. TUBERCULOSIS: (1) Tuberculosis (All Forms).- A seasonal fluctuation is observable in the mortality from tuberculosis (all forms) in which the maximum proportion of deaths occurs in March, April and May whilst the minimum proportion is recorded from August to November. The extent of this seasonal change is represented by a variation of approximately 20 per cent. above and below the average number of deaths per month; (2) Pulmonary Tuberculosis.- The seasonal change in the mortality from pulmonary tuberculosis resembles that from all forms of the disease except that the maximum and minimum points are recorded somewhat earlier in the year; (3) Meningeal Tuberculosis.- In meningeal tuberculosis the seasonal variation in mortality is very much more pronounced, amounting to a fluctuation of approximately 30 per cent. above and below the average number of deaths per month. The maximum and minimum points occur later in the year, namely in May and November respectively; (4) Other Forms of Tuberculosis.- The variation in mortality observable in the remaining manifestations of tuberculosis, resembles that of pulmonary tuberculosis in its extent, but that of meningeal tuberculosis in time; (5) Sex. - No evidence exists which supports the view that the female sex is more susceptible than the male sex to seasonal variation in the mortality from tuberculosis, despite the fact that certain clinical features in the course of the disease supported such a contention. IIIB. THE GENERAL MORTALITY AND CERTAIN SELECTED DISEASES: (1). GENERAL MORTALITY: The maximum mortality from all causes occurs in March, and the minimum in September. The seasonal reaction is similar to that observed in tuberculosis in its excursion above and below the average number of deaths per month though the maximum and minimum points occur somewhat earlier in the year; (2). INFLUENZA (ENDEMIC), PNEUMONIA, AND THE PRINCIPAL RESPIRATORY DISEASES (NOT TUBERCULOUS): The seasonal trend in the mortality from these diseases is very pronounced indeed, the highest and lowest returns being made in March and September; (3). APPENDICITIS AND SYPHILIS: The seasonal variation in the mortality from appendicitis and syphilis is relative/slight. (4). CANCER: There is no seasonal variation in the mortality from malignant disease. IIIC. THE RELATIONSHIP OF AGE TO SEASONAL VARIATION IN MORTALITY: Young children (below five years of age) are very much more susceptible to seasonal/ 211 seasonal variation in disease than older subjects. This is true of the collected causes of death, but in tuberculosis the susceptible age extends to 15 years before the seasonal variation in mortality commences to diminish. IIID. THE RELATIONSHIP OF CLIMATE AND WEATHER TO SEASONAL VARIATION IN TUBERCULOSIS: Climate is undoubtedly an important factor in the determination of seasonal variation in tuberculosis. This may be observed in the available evidence on mortality in different countries, and in clinical observations recorded in different latitudes. It is probable that less significance attaches to weather in the causation of seasonal trends in tuberculosis however important it may be in acute respiratory infections. THE CAUSES OF SEASONAL VARIATION IN DISEASE: The causes of seasonal variation in tuberculosis, and in almost all diseases are probably very complex. But they may be stated to be associated with (a) changes in the human subject, and (b) changes in the microorganism. The evidence available from this work and from other sources is discussed from this point of view. It would appear that changes in the "soil" are the more important, but that changes in the "seed" govern to some extent the nature of the variation which results. PRACTICAL IMPLICATIONS: Consideration is given to the importance of seasonal fluctuations in the treatment of tuberculosis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available