During second epidemiological survey carried out in 1972-73, special efforts were made in 21 of 62 villages belonging to first survey (1961-62) to study the demographic changes and fate of TB cases after an interval of 12 years.

The findings were: The increase of dejure population was about 20% over a period of 12 years i.e., an annual increase of 1.7%. The age structure had altered mainly due to significant increase in the age group 60 years and above – 51% to 64% indicating aging of population. The loss of original population after 12 years was 44%, of which 33% was due to migration and 11% due to death. The overall migration was more among females. The migration rate was higher in younger age group, being highest in 10-19 years (49%), next in 0-9 years (38%). Thus, overall migration in 0-19 years was 43%. The death rate was highest in 60 years and above (58%). It varied from 4-9% in age group 0-39 years. Original population available after 12 years for re-examination was 56%. Distribution in different age groups were; 0-9yr = 57%, 10-19yrs = 47%, 20-49yrs = 66%, 50-59yrs = 44%, 60yrs and more = 28%.

Out of 88 X-ray suspect cases of earlier survey, 87 could be identified and present status of 72 were known. Of them, 16 were normal, 12 and 4 found to be suspect cases and bacillary cases respectively and 40 had died. Of the remaining fifteen, 11 migrated and 4 not examined. Out of 14 bacillary cases, 13 could be identified. Of them, 3 were sputum negatives (2 normal and 1 suspect case) 9 had died and 1 migrated.

The findings of the two follow-ups conducted passively, in a slum area of Bangalore city, each at an interval of one year, are presented here. The objectives of the follow-ups were to study the migration, episodes of sickness and health status of sick people of initial survey over a period of time in the pediatric age group. The information was collected by two ways: (1) by visiting each house to collect information on sickness among them during the preceding year as per the questionnaire. (2) Going through the records of the Area Health Centre about various morbidities among the residents of the area pertaining to symptoms, diagnosis and treatment during any year noted.

Migration had occurred upto 7% in 0-9 year age group within first year and no migration during second year in 0-4 year age group. Out of 400 children belonging to 0-14 years, had symptoms related to respiratory system. In all, 5 children were diagnosed as case of active primary tuberculosis, non-e died in two years and one had persistent respiratory symptoms. Hospital records showed that only 1 out of 5 had attended any health facility with respiratory symptoms. The usefulness of passive follow-up without clinical investigations as a tool, needs to be reviewed. Most of the symptomatics do not go to hospital. Diagnosis cannot be arrived at by passive follow-up. It may be necessary to decrease the interval of follow-ups if it is desired to get precise idea on frequency of episodes of sickness, as most of the sicknesses are forgotten by the population with passage of time.

The purpose of the study was to establish the rate of emigration in a random selection of villages, with a view to forecast the likely loss of population in a follow up study on BCG vaccination in the area. The study was carried out in the total population belonging to 35 villages of Channapatna, Devanahalli, Magadi and Nelamangala taluks of Bangalore district in April 1960. Demographic characteristics such as birth and death rates, immigration rates and proportion of persons temporarily absent, were also studied. The head of the household if absent, any other responsible adult was interviewed on a house to house basis, regarding the composition of the family, according to the National TB Institute manual for census takers. Estimation of migration was to be based on the registered population of the current day, the population exactly one year ago and all relevant events during the intervening year.

The thirty five villages surveyed were found to have a population of 13,838 persons at the time of interview. This figure includes: (A) 13138 persons in the household at the time of census taking also belonged to it one year ago. (B) 470 persons born during the past year. (C) 230 persons immigrated during the past year. (D) 200 persons dead during the past year. (E) 307 persons emigrated during the past year & (F) 770 persons temporarily absent. The net increase in the population from April 1959 to April 1960 was, 193 persons or 14 per thousand.

It was estimated that not more than 5% of the population would be lost by emigration over a period of two years. About 1/3rd of the emigration is within the same taluk. Only a small portion of the emigrants are above 30 years of age. It is also found that a good proportion of women's migration is due to marriage. The study findings revealed that the hypothesis that large number of people leave the village every year, making BCG coverage impossible could hardly be upheld.