KS Aneja & AK Chakraborty: NTI Newsletter 1978, 15, 9-14

Because of slow nature of decline and the long span of the declining phase spread over a couple of centuries it is difficult to obtain direct evidences of decline by conducting studies over relatively short period of time and comparing the rates so obtained. Therefore, one has to take into account the total current epidemiological situation by considering both indirect and direct evidences to know the trend of disease; A) Indirect Evidence i) tuberculosis morbidity being largely confined to older age groups, prevalence rates being similar in both rural and urban areas and a wide gap between infection and disease rates (38% and 0.4% respectively). ii) Information on tuberculosis mortality although not very reliable, still appears to suggest that the disease, since the turn of the century, has taken a declining course. It has been observed to be 253 for 100,000 persons in 1949 in Madanapalle and 84 per 100,000 in Bangalore during 1961-68. There might he some regional variations but there is definite suggestion of decline in the mortality. iii) Considerable change in clinical presentation from more acute and exuberative to a more chronic disease and a shift in age during last quarter of the century, a marked decrease of the concomitant problems of pulmonary tuberculosis, are all indirect indicators of decline. B) Direct evidences are: i) Information available from various epidemiological surveys in India indicates no change in the prevalence rates of bacillary tuberculosis in the country during the last two decades. ii) The longitudinal survey conducted in south India and the other in Delhi have shown a declining trend of the disease specially in the younger age group. However, to see that the trend is secular or not, these surveys have to be continued for a longer period of time - atleast 15-20 years.

From the above evidences it may be reasonable to infer that there is a gradual but slow natural declining trend of tuberculosis in the country. To hasten the process of natural decline and to give relief to a large number of prevailing cases, anti tuberculosis measures should be further strengthened.