Biomedical subjects
Publications and source records attributed to J B Cookson.
Forced vital capacity, forced expiratory volume in one second and peak expiratory flow rate were measured in 125 adult Batswana who were without evidence of pulmonary disease. Regression co-efficients suitable for the calculation of normal values for these parameters are presented. Results are similar to those in other Negroid populations but lower than in Caucasian subjects.
The prevalence of chronic bronchitis in the African population of a small township in Rhodesia was estimated using two questionnaires, both based on those of the British Medical Research Council. The first, a screening questionnaire, was put to 9768 subjects aged 5 years and above and the second, a more detailed questionnaire, to random selections of these grouped according to their replies. Repeat interviews were used to assess the accuracy of the questionnaires. The overall prevalence of chronic bronchitis was 1.12%. This is much lower than most other surveys elsewhere. There was little evidence of an increase in prevalence with age, and rates were not significantly different in the two sexes. The prevalence of complications and of other chest symptoms was correspondingly low. The proportion of bronchitics who smoked was not significantly higher than in the controls. Amounts smoked, however, were generally much lower than in other populations, and this, together with low levels of pollution, probably account for the prevalence findings.
Experience with a new serological method for the diagnosis of tuberculosis is reported in a predominantly black population. We have found that in only 69% of 167 patients was there agreement between serology and the presence or absence of tuberculosis. Both false positive and false negative results were common. Of 47 healthy controls, 80% were positive. These results are less satisfactory than previous studies but differences in the reading of the results seems an unlikely explanation. Differences in the populations studied may be an important factor.
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Forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow were measured in 141 African men and 102 African women aged 20 and above. Prediction formulae relating each measurement to height and age were drawn up and are presented. Rhodesian Africans have lower values for these measurements than subjects in some Europen and North American series, but broadly similar values to those of Africans elsewhere.
Eighty adult asthmatics living in an African city had a significantly higher serum IgE level (799 u/ml) than the control group (350 u/ml). A high proportion (78.7%) of the asthmatics had demonstrable circulating mite-specific IgE antibodies. The rural population of a filariasis endemic region was investigated and although no allergic subjects were identified, the group had a significantly higher IgE level (1613 u/ml) than the asthmatics and also showed a relatively high incidence of grass pollen-specific IgE antibodies (35%). The discrepancy between clinical history and laboratory results supports the mast cell saturation hypothesis and suggests: (a) an explanation for the susceptibility to allergy of African and Asian immigrants to Great Britain, and (b) a practical approach for preventing allergic reactions in vivo.
Of eighty African asthmatics, sixty-three had significant levels of specific IgE against the house dust mite dermatophagoides pteronyssinus. By contrast, grass-specific IgE was found in six patients and mould-specific IgE in none. Sixty-three patients also had symptoms predominantly during the rainy season. Positive skin tests against D. pteronyssinus correlated well with the presence of mite-specific IgE, as did the size of these skin test weals with the amount of specific IgE. For grass pollen and moulds there was no such relationship. There was no correlation between a history of sensitivity to house dust and either skin tests or specific IgE against D. pteronyssinus. The results support previous findings that it is allergy to house dust mite and not to grass pollens or moulds which is important in producing the seasonal symptoms in our patients.
The relationship between seasonal asthma and sensitivity to the house-dust mite has been investigated in a country with large seasonal variations in relative humidity. Of seventy-eight African asthmatics, 64.1% gave a history probably suggestive of sensitivity to house-dust, and 55.1% a history strongly suggestive of such sensitivity. On skin testing, 35.9% had strong reactions to the house-dust mite Dermatophagoides pteronyssinus, compared with 1.9% of fifty-one matched controls without symptoms of chest disease. Few had either a history or skin tests suggestive of pollen or mould sensitivity. Most of the asthmatics were worse during the hot, wet season when the humidity is highest. This is also the time when in-patient asthmatics are most numerous. D. pteronyssinus grows well in warm, damp conditions and it is suggested that sensitivity to this mite may play a significant role in the marked seasonal changes seen in our asthmatic patients.
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