Search

An analysis of data from two successive tuberculosis prevalence surveys (conducted at an interval of 18 months) in a random sample of villages in Bangalore District, South India, has shown that the term "a case of pulmonary tuberculosis" does not represent a single uniform entity, but rather embraces cases of several types, differing considerably in their mortality experience, tuberculin sensitivity, results of X-ray and sputum examinations, and in the reliability of their diagnosis.The status at the first survey of the cases found at the resurvey and that at resurvey of those found at the initial survey give an indication of changes with time. Such changes show considerable differences for the various types of cases and provide another dimension to study the differences among them. The authors consider that, in spite of the great need and importance of a single straightforward definition of a case, no such definition is suitable for all situations; there is no other option but to continue to use more than one definition.Although, theoretically, finding a single bacillus in the sputum should be adequate proof of pulmonary tuberculosis, it is shown that finding of a few bacilli, 3 or less, is probably far too often due to artefacts and should not be the basis for a diagnosis.The findings also well bear out the notion that positive radiological findings, in the absence of bacteriological confirmation, indicate, not pulmonary tuberculosis, but only a high risk of the disease. Direct microscopy appears to be a consistent index of disease but, in community surveys, has the limitations of missing a substantial proportion of cases and of adding some false cases. The extent of these limitations, so far as symptomatic patients in a community tuberculosis control programme are concerned, remains to be investigated.

In the District Tuberculosis Programme in India, which is part of a national programme, case-finding and treatment of pulmonary tuberculosis are integrated into the general health services. With such an integration, it is desirable, in order to forecast possible achievements, to understand the additional work-load that the programme will impose upon the existing health institutions and to assess the potential of these institutions for case-finding and treatment.The operational study described in this paper was made under programme conditions in a district in South India and is an examination of the case-finding potential of rural health institutions, using direct microscopy of sputum for diagnosis, and of the additional work-load involved by such case-finding. Under the conditions found in the course of the study, it is clear that a substantial proportion (at least 65%) of pulmonary tuberculosis cases prevalent in the district can be detected by the existing staffs with an easily manageable work-load.

A controlled study on the enhancing of tuberculin allergy by one or more earlier tuberculin tests was carried out in a previously untested and unvaccinated population, in an area where the prevalence of non-specific allergy was known to be high. The results have shown that a test with 1 TU of PPD RT 23 in Tween 80 diluent causes subsequent tests to elicit significantly larger reactions. This enhancing effect is more marked among those with initial reactions of 8-13 mm to 1 TU or 10 mm and more to 20 TU. There is practically no enhancement among those whose reactions to 20 TU measure 0-4 mm or even 0-9 mm. Even in the group with reactions of 10 mm and more to 20 TU only some individuals show evidence of enhancement. The enhancing of allergy increases with age.The addition of a 20 TU test increases the enhancement of allergy but mostly among those with reactions of 8-13 mm to 1 TU.The findings suggest that enhancement may be more marked in communities with a high prevalence of non-specific allergy.