The degree of the risk of infection and disease in man from drug resistant strains of mycobacterium tuberculosis is not clear. An increase in the prevalence of primary resistance indicates the extent of such risk while an increase of secondary or acquired resistance could be considered as a problem of the individual patient and may reflect limitations of his treatment.

The present report describes the prevalence of strains with acquired or primary resistance or of sensitive strains found in 3 successive surveys in a sizable random sample of village in a south Indian district. Changes in the status of cases with such strains from one survey to another and their infectivity among household contacts are also described. The prevalence of tuberculosis infection among household contacts of cases with acquired resistance to isoniazid was significantly higher than those with primary resistance or with sensitive culture. This was probably due to the longer duration of sputum positivity of isoniazid resistant strains at the time of diagnosis. But infectivity as judged by the incidence of new infection among household contacts was generally less for cases with acquired or primary resistance than for cases with sensitive cultures, though the difference observed was not statistically significant. A large number of culture positive cases especially those with primary resistance had no radiological evidence of active pulmonary tuberculosis. The prevalence of primary resistance was high in certain categories of cases and the differences between cases with primary resistance and those with acquired resistance were many and large. It was suggested that this could be due to the primary resistant cultures being those of atypical mycobacteria, despite positivity in the niacin test. There was a significant increase in the number of cases with acquired resistance to isoniazid at the third survey owing to the irregular treatment and supply of INH alone after the second round. The prevalence of primary resistance at the three rounds was almost the same.

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.

This paper estimates the natural trend of tuberculosis in rural south India and the potential epidemiological impact of a few selected programmes on this trend, by using the values of important variables and parameters derived from a longitudinal epidemiological study conducted in 1961-68 in Bangalore district by the National Tuberculosis Institute (NTI), Bangalore. The values are fed into an epidemetric model and the final outputs of computerization derived are incidence of disease (in both absolute and relative terms) and cumulative future prevalence of disease.

(1) An annual average input of new generations of 3.16% has been derived for a population of 1 million by using a simplified fertility rate formula. A constant reduction 0f 1% per year has been assumed until fertility rate has reached 50% of its starting value. The assumption is that any reduction in fertility due to current family planning programmes will have a considerable impact on the size of the population and on the epidemiological situation. Further demographic assumptions are, excess mortality applied to groups of active cases and fatality among untreated cases. (2) The population is subdivided into the following epidemiological groups: (i) non-infected, (ii) infected for – (a)< 5 years, (b)= 5 years, (iii) protected by BCG, (iv) active cases - (a) non-infectious, (b) infectious and (v) previous cases. Initially groups (iii) and (v) are given zero values. The future risk of infection is adjusted to the force of infection, which is assumed to be reduced to 1/7th when a case is successfully treated. Morbidity rates include transfers from infected group to active cases group during 5 year periods. (3) A spontaneous healing rate of 50% and a cure rate of 80% after chemotherapy are assumed. Protective effect of BCG is given three values: 30%, 50% and 80%, with uniform annual reduction of 1% (4) Case detection and treatment (CF/T) is given two values: 66% and 20%. Coverage for BCG limited to 0-20 years is assumed to be 66% or 30%.

The computer simulation output for natural trend shows that the absolute number of new cases increases considerably while the incidence rate do not warrant firm conclusions about any long term trend. All programmes considered have considerable potential impact. The CF/T programmes will reduce the incidence after 25 years by only 12% compared to reduction of 17% by the BCG programme. In general, the effect of CF/T will be more immediate and of BCG will be seen much later. To avoid the drawbacks of incidence as an indicator of tuberculosis situation, the cumulated future prevalence is taken as the tuberculosis problem. To adjust for the present significance of future cases as part of the problem certain discount rate have been applied. The CF/T programme and the BCG programme with 50% protection lead to 69% problem reduction, if not discounted. With increasing discount rates, CF/T has an advantage over BCG. The actual problem reduction will be higher than that estimated if improvements in the standard of living are expected during the coming years.

In conclusion, data on the dynamics of tuberculosis situation in rural south India, obtained by NTI, Bangalore when fed into a mathematical model, many predictions about the future tuberculosis situation were made under a wide range of hypothetical assumptions.

A rural population of 65,000 belonging to 119 randomly selected villages of Bangalore district was repeatedly examined four times during 1961 to 1968, by tuberculin test, X-ray and sputum examinations, to study the epidemiology of tuberculosis without any active anti-tuberculosis measures. The interval between the first and the fourth examination was 5 years. The coverage of various examinations at different surveys were very high.

The main findings of the study are: Prevalence rate of tuberculous infection in the population was about 30% (among females 25% and males 35%). The overall prevalence rates of infection were fairly constant at all the four surveys, but a steady decrease in the prevalence of infection was observed in the age group 0-24 years. Annual incidence rate of infection on the average was about 1%. During the study period, the incidence of infection showed a decline from 1.63% to 0.8% for all ages combined. Prevalence rate of disease ranged from 337 to 406 per 1,00,000 population during the study period, the highest being at the time of first survey and lowest at the time of third survey. For the younger age group of 5-34 years, the rates showed continuous decrease during the study period. Annual incidence rate of disease ranged from 79 to 132 per 1,00,000 population, highest being between first and second surveys and lowest between second and third surveys. The incidence rate in younger age groups below 35 years showed a decline during the study period. Those with tuberculin test induration of 20mm or more had highest annual incidence rate of disease. The annual incidence rate of bacteriologically confirmed disease in the three radiological groups of population was (i) 185 per 1,00,000 with normal X-rays, (ii) 958 per 1,00,000 with abnormal shadows judged as inactive tuberculous are non-tuberculous and (iii) 4,530 per 1,00,000 with abnormal shadows judged as active or probably active tuberculous but bacteriologically not confirmed. The third group constituted 1% of the total population and contributed 34% of the total incidence cases. In each of the above three radiological groups, the incidence of disease was highest among those with tuberculin test induration of 20mm or more to 1 TU RT 23 with Tween 80. Those with 20mm or more tuberculin test induration in the third radiological group constituted 0.45% of the total population but contributed 27% of the total incidence cases. Incidence rate for males was nearly double that of females. More than half of the new male cases were 35 years of age, whereas more than half the females were below the age of 35 years. Out of 126 cases followed up at three subsequent surveys over a period of 5 years, 49.2% died, 32.5% got cured and 18.3% continued to remain sputum positive. Both death and cure rates were highest during the first one and a half year period.

About 30% of newly detected cases come from population uninfected at an earlier survey. Both infection and disease showed a decline in the younger age group. There was no evidence of an increase in drug resistance among newly diagnosed cases. Incidence of cases showed a higher natural cure. These findings indicate that tuberculosis cases are not a uniform entity. There can be different gradations from the point of view of diagnosis and ability to benefit from treatment. The differences between male and female patients with regard to death and cure rates support this view

This paper reports on a study conducted in the year 1975 to estimate yield of tuberculosis cases from multiple sputum specimens, and work out correction factors to be applied to estimates based on small number of specimens. Eight sputum specimens were collected within a fortnight from each person with an abnormal chest X-ray during an epidemiological survey in 77 villages in a district of south India. Each specimen was examined by Ziehl-Neelsen technique of microscopy and culture. In all, 3,199 persons were referred for sputum examination and results of all the eight specimens were available for 1,652. Of the latter, 64 were culture positive.

The first specimen detected 58% of the culture positives and the additional positives by later specimens generally decreased. The contribution from the first specimen was 71% for cultures showing good growth and 19% for cultures with scanty growth. Similarly for positives on both culture and microscopy, first specimen detected 87% whereas the corresponding proportion was 32% for those positive only on culture. The type of specimen (viz., spot or overnight) and age or sex of the case did not influence the yield from multiple examinations. The precision of an estimate of prevalence will depend on the number of specimens on which it is based and the coverage obtained in the collection and examination of specimens. Correction factors to be applied to such estimates based on one or two specimens, for various levels of coverage have been presented. For example, an estimate of prevalence based on one sputum specimen with 90% coverage will have to be nearly doubled to get a more precise estimate. Using these correction factors, revised estimates of prevalence have been presented for a number of prevalence surveys conducted in India. It has been estimated that the total number of infectious cases in India at present may be at least 3 million, as against 2 million according to earlier estimates.

The five year longitudinal epidemiological study in south India (1961-68) showed that a considerable proportion of bacteriologically proven cases found in a survey got cured naturally without the facility of organised treatment in the survey area. This "natural cure" could be an epidemiologically significant phenomenon- depending on the stability of such a cure or in other words, the frequency of relapses among the naturally cured. In all, 108 naturally cured cases of tuberculosis out of a total of 269 cases, from among about 62,000 persons surveyed twice, were followed up for varying periods of 1 to 3½ years.

It was observed that the average relapse rate was 85.4 per 1000 person years of observation, there being no difference between the two sexes. Relapse rates were however higher in persons aged 20 and more compared to those 5-10 years old. Relapses were not dependent on the bacteriological status at initial diagnosis i.e., whether positive by culture alone or positive by smear and culture. The death rate among the naturally cured was 42.7 per 1000 person years and together with relapse constituted the unfavourable fate after natural cure. It has been calculated that as an input, adding to the pool of bacillary cases in the community, the ratio of relapse cases to cases arising afresh from the general population in a year would roughly be in the order of 1:16. It is concluded that the naturally cured status could be considered as an epidemiologically favourable situation, though much less so when compared to the chemotherapeutically achieved cure.

The study was undertaken in a sample of 103 villages of 3 sub-divisions of Bangalore district as a part of the 5 year study of epidemiology of tuberculosis between 1961-68. The follow ups were done at 1.5, 3 & 5 years after the first survey. The entire population was offered tuberculin test with 1 TU RT 23, a second test with 20 TU RT 23 to those persons who were having reactions of 0-13 mm to 1 TU. All aged 5 years or more were offered 70mm photofluorograms at each survey. Two specimens of sputum were collected from persons having abnormal X-ray shadows for examination of tubercle bacilli. Procedures were uniform at each survey. The population was divided into three groups on the basis of their tuberculin reactions: (a) reactors to 1 TU (infected with M.tuberculosis), b) non-reactors to 1 TU but reactors to 20 TU (infected with atypical mycobacteria), c) non-reactors to both 1 TU & 20 TU (not infected with either M.tuberculosis or other mycobacteria). Incidence of disease and crude mortality were studied separately among these groups.

The five year incidence of culture positive disease was the highest among 1 TU reactors and the least among reactors to 20 TU. In the younger age group (5-14 years) the five year incidence of culture positive disease among reactors to 20 TU was significantly lower compared with that among 20 TU non-reactors. The reduction of incidence of culture positive cases in the former group over that in the latter was 75% for culture positive cases and 61% for combined culture positive and negative disease. As regards crude mortality, the overall rate was significantly lower among 20 TU reactors compared with non-reactors. Even if the significance of the finding on crude mortality is debatable, it could be concluded that non-specific infection provides some protection against development of tuberculosis, at least in younger age groups.

The data from a tuberculosis prevalence survey carried out in three taluks of Bangalore district in south India during 1961-68 were analysed to study (i) the prevalence of non-specific sensitivity in the community i.e., prevalence of infection with mycobacteria other than M.tuberculosis, as found by testing the population with tuberculin RT 23 of a lower strength (1 TU) and higher strength (20 TU), both with Tween 80 and (ii) additional boosting if any, resulting from testing with higher dose of tuberculin, immediately following a test with 1 TU RT 23.

The level of demarcation between infected and uninfected with 1 TU was 0-9 mm induration size and this negative group tested with 20 TU dose induration of 8 mm or more was considered positive. Prevalence of infection with M.tuberculosis in the community were 2.1% in 0-4 years, 7.9% in 5-9 years, 16.5% in 10-14 years, 33.2% in 15-24 years and overall 14.5% in 0-24 years of age group. Infection rate with other mycobacteria were 12.9%, 44.9%, 66.2%, 62.4% and 45.7% respectively in the above stated different age groups.

Testing the population with 20 TU RT 23 following a 1 TU test was found not to boost the tuberculin reactions over that observed on a single test with 1 TU only.

Out of 56,146 persons without BCG scar examined at the first survey in 119 villages of Bangalore district (1961-63), 22,468 were subsequently examined 3 times over a period of five years by tuberculin test, X-ray and sputum at intervals of 1½ years to 2 years. No organized anti-tuberculosis services were provided in the study area. On the basis of tuberculin status and chest X-ray interpretations, the population was classified into 6 sub groups for the study of risk of sputum positive disease viz., Normal X-ray (N), Inactive Tuberculosis (AB) & Probably Active Tuberculosis (CD) and each of these into tuberculin positives and negatives.

The annual incidence of sputum positive disease observed was 1.45 per thousand among 18,207 eligible persons aged 5 years and more. The incidence of the disease in tuberculin positive group was 7 times as compared to that among tuberculin negatives. The incidence rate of bacteriological disease was 0.79 per thousand among X-ray normals (N) of the first survey; it was 3.73 per thousand among persons with inactive tuberculous lesion and non- tuberculous shadows (AB) and 26.04 per thousand among the group of persons with active or probably tuberculous shadows (CD). Of the total incidence cases, 76% were contributed by the tuberculin positives. The group of active or probably active shadows (CD) contributed 26.6% of the total new cases. The population without any radiological abnormality (N) contributed 48.2% of the new cases.

A study was carried out mainly to find out the prevalence and incidence of sputum negative active pulmonary tuberculosis (suspect cases) among 35,876 persons aged 5 years and above in rural areas of Bangalore district during 1968-72. Two surveys (I & II) at an interval of 3 months, succeeded by a follow up examination of the X-ray abnormals of the earlier surveys, were conducted in the same villages. Examinations at each survey consisted of tuberculin test, X-ray and sputum examinations. X-rays were interpreted individually at the time of each survey by single picture interpretation method and subsequently by Joint Parallel Reading (JPR) method to arrive to a diagnosis. In the JPR method X-ray readings and their comparison was done by a panel of three X-ray readers with full knowledge of age, sex, result of sputum examination and tuberculin test of each person with chest abnormality at any of the three surveys.

On a single picture interpretation the overall prevalence rate of suspect disease was found to be 5.4 per thousand at I survey and 4.59 per thousand at II survey. There was no significant difference in the overall age and sex specific prevalence rates of suspect disease between I & II surveys. Incidence of suspect disease at the end of 3 months was 2.24 per thousand. By JPR method the prevalence rates of suspect disease was 3.2 per thousand at I survey and 3.6 per thousand at II survey. The prevalence rates by single picture method were overestimated to the extent of 38% at I survey and 19% at II survey when compared with those found by JPR method. At I survey prevalence rates on JPR method was significantly lower than by single picture method. This was not so at II survey. Similarly, incidence rate of 0.2 per thousand of suspect disease on JPR was about 1/10th of that found by single picture method.

The incidence of bacteriologically positive cases in 6 months from among suspect cases on JPR was found to be 28%. Majority (76%) of non-tuberculous or inactive tuberculous shadows continued to remain as such after 6 months and about a quarter (23%) became normal. Incidence of bacteriologically positive cases from this group was minimal. Of 19,640 persons with normal X-rays 134 (0.7%) developed new shadows in 3 months; 103 (0.5%) cleared after 2-12 weeks (fleeting shadows). Mis-interpretation of the latter as active tuberculous may falsely boost the estimates of suspect disease to the extent of about 5%.

In a five year epidemiological survey conducted by National Tuberculosis Institute (NTI) from 1961 to 1968, the population was mainly classified into three epidemiological groups (i) with no radiological abnormalities seen in the lungs (Group N) (ii) having X-ray shadows of non-tuberculous etiology or tuberculosis etiology but judged as inactive (Group M) and (iii) with shadows of tuberculosis etiology judged possibly or definitely active but negative on culture (Group S). The objective of this paper is to compare the characteristics of cases coming from the above three groups (N, M and S) in respect to bacillary disease status (a) at the time of diagnosis and (b) after a lapse of time (Fate). Out of the total 172 new cases diagnosed during three follow ups, 70 were diagnosed between I & II surveys, 40 between II and III and 62 between III-IV surveys. In the two 18 months follow up periods, 45 of the total new cases had come from Group N, 31 cases from Group M and 34 cases from Group S, corresponding figures for 24 months follow up (III & IV surveys) were 26, 26 and 10 respectively.

In the 18 months follow up it was observed that proportion of new cases positive on culture in the three groups were not significantly different. Comparison of fate of cases coming from three groups were similar in terms of cure, death and culture positivity. The findings point out clearly that not only development of disease but also the fate of cases is independent of pre diagnosis status of the new cases.

From all the 3 groups, disease developed more rapidly in some cases than in others. This reveals that tuberculosis cases are not an uniform entity from the point of view of development of the disease and cure.

Information on cause specific mortality rates due to tuberculosis in India is inadequate. In the study under report, these have been estimated based on the data obtained from a five year epidemiological study of 119 villages of Bangalore district in south India. For this purpose, the estimated number of excess deaths due to causes other than tuberculosis among patients of tuberculosis, have been attributed to the disease.

The annual mortality due to all causes on 5 year observation could be calculated as 893 per 1,00,000 population (9%) aged 5 years and above. Agewise as well as overall mortality rates were not different from survey I & II, II & III & III & IV. The average rate of the periods is calculated to be 84 per 1,00,000 annually. The death rates were the highest in 55 years and above age groups, lower in 5-14 years and showed an increasing trend with age. Compared to the estimates of tuberculous deaths in India available for 1949 (about 250/1,00,000), the present rates were lower.

The incidence rates of sputum positive pulmonary tuberculosis (cases) from the five year follow ups of a rural population done by National Tuberculosis Institute were reported on the basis of studies at intervals of one and a half to two years. Information on fate of cases was also likewise reported. These parameters appear to be imprecise since incidence and fate of cases at shorter intervals were not taken into account. Thus, the information on incidence of pulmonary tuberculosis in India is meager as compared to that on prevalence of disease. Therefore, a study mainly to find out the incidence and fate of cases at shorter intervals of 3-6 months was undertaken in 87 randomly selected villages of Nelamangala sub-division, Bangalore district which was one of the 3 sub-divisions where repeated epidemiological surveys had been conducted between 1961-68. The sample of villages in the present investigation was other than that included in the earlier report. Organized Case-finding, anti-tuberculosis treatment and BCG vaccination neither existed nor could be provided in the area till the completion of the study. The present study was conducted between 1968-1972.

This study conducted among 30,576 persons has shown that incidence of cases over a period of three months was 0.99 per thousand and was not much different from the annual rate of 1.03 per thousand reported on the basis of repeated surveys at longer intervals. That the three months rates were not a quarter of the annual rates meant that the procedure of calculating incidence rates on the basis of surveys done at varying intervals after adjusting for the interval had to be used with great caution. The study of fate of cases showed that cases converted or reverted even at shorter intervals and this appeared to be going on continually in the community. However, incidence of cases and cure and death from among the existing as well as the fresh cases kept on balancing each other so that the prevalence rates of cases studied at shorter or at longer intervals did not show variations.

Mortality from tuberculosis is an important epidemiological parameter for defining the problem of tuberculosis in any country. But due to lack of systematic recording and reporting system, precise information on cause of death is not available in our country. An attempt has been made to estimate the case fatality of tuberculosis cases as well as mortality of cases diagnosed in a longitudinal study conducted from 1961-68 in Bangalore district. Crude mortality of cases is defined as the ratio of total deaths observed among cases to the total number of cases observed, while case fatality is defined as the ratio of deaths that have occurred due to tuberculosis to the total number of cases investigated.

The overall observed annual crude mortality was 14.8%, while among culture positive smear positive (C+S+) it was 21%. An upward trend was seen with the increase in the age. The overall annual crude mortality among culture positive smear negative (C+S-) cases was 9.5% which is significantly lower than that among C+S+ cases. The death rates among old and new cases at the end of 18 months were 16.7% and 13.7% respectively. No statistical difference was found in the crude mortality either among old and new cases or in relation to the interval of diagnosis. Case fatality due to tuberculosis was computed by calculating the deaths among non-tuberculosis population of the same area and during same period and eliminated from the total deaths observed among tuberculosis cases. The case fatality of tuberculosis was found to be 13.3%. It was further observed that out of the total 38 deaths among cases, 89% were due to tuberculosis and 11% were due to non-tuberculosis causes.

During a longitudinal survey, carried out in 119 randomly selected villages of Bangalore district for studying the time trend of tuberculosis, the average infectivity of a case over a period of one and a half years was found to be six. In 1986 i.e., 25 years after the start of I survey, 61 persons belonging to one village called Nunnur who were found newly infected between I & II surveys, were interviewed. Further, a general study of the layout of the houses and public facilities in the village was made. However, in Nunnur, there was just a single bacteriological case (index case) identified at the I survey. This index case was resident of household numbered 80 in the main village. This case study investigates the background of the observed high infectivity. The incidence rate of infection in Nunnur was 9.5% in 1½ years which is higher than the overall average rate of 4% as well as rate for 30 other single case villages i.e., 3.5%. The investigation reveals that at least 21 persons., found newly infected at II survey, had varying levels of contact with the index case. The remaining 40 infected persons could not be linked, either directly or indirectly, to any other known bacteriological case including the index case in the village. All the persons identified as infected at II survey were distributed throughout the village, beyond the likely zone of infection of the index case.

It has been postulated that BCG scar disappears in a good number of children and some of the vaccinated children will get included in the non- vaccinated group and cause difficulty in interpreting the results of tuberculin test. It was decided to analyse information on BCG scar status in the younger population of a rural community in 3 taluks of Bangalore district with an objective to find out whether disappearance of BCG scar is dependent on the age of the child, size of post-vaccination induration at initial survey and tuberculin sensitivity status of children in whom BCG scar has disappeared, in comparison with children in whom the BCG scar has not disappeared. In all, 1095 children aged 0 to 14 years were found with BCG scar in 119 randomly selected villages during an epidemiological survey done in 1961 at the time of intake. Following two groups of children were studied for disappearance of the scar. Of them, a) 796 children who had BCG scar at the first survey, and whose BCG scar status was available at 4th survey, b) 299 who showed no BCG scar at first survey but were found with BCG scar at 2nd survey and whose BCG scar status was available at 4th survey.

Of the BCG scars recorded at intake, 26.4% and 32.5% disappeared subsequently during three and a half and five year periods respectively. The waning of BCG scars was independent of age of the child and tuberculin sensitivity status at intake. Tuberculin sensitivity status in children in whom scar had disappeared was the same as that found in children in whom scar had persisted at intake and after five years. The misclassification of children, in whom scars have disappeared, as unvaccinated leads to a difficulty in interpreting the results of tuberculin test done for the purpose of computation of the Annual Risk of Infection. Further, the extent of misclassification increases in proportion with the increase in BCG coverage of the population. This finding justifies the practice of identifying the demarcation level on the basis of the distribution of tuberculin induration sizes for classifying the infected persons in a population in each survey.

A study was conducted in 55 randomly selected villages of Nelamangala taluk, Bangalore district in 1975 (1) to estimate the prevalence of symptoms in the general population during the two months prior to the epidemiological survey, (2) to study the nature of action taken by these symptomatics and, (3) to find out through sputum examination as to how many of them suffer from pulmonary tuberculosis. The entire population was interviewed and sputum was collected from those aged five years and above having symptoms continuously for seven days and more. A coverage of 98.8% was obtained. Symptomatics among the directly interviewed were almost double (32.3%) of those who had to be interviewed by proxy (16.8%). Proportion of symptomatics were higher in the age groups twenty years and above. 24.8% were symptomatic during the reference period of two months and 16.7% had symptoms on the day of interview. ll.1% were found to have chest symptoms. The prevalence rate of tuberculosis was found to be 21 per 1000, (for males 28 and females 14). Cough was the most prevalent and the symptom of longest duration.

The findings suggest that symptoms questioning should focus more on cough and its combination with other symptoms. Symptoms questioning as a tool to detect cases has less potential than X-ray, but data reveal that leading questions can elicit more information on symptoms and action taking. The manner of action taking was the same for chest symptoms as for other symptoms and the proportion taking action is also the same for males and females. Government health facilities are found to be the most important source of relief, indigenous medicine having some importance marked second and the private practitioners ranking only third.

Persons suffering from pulmonary tuberculosis generally experience symptoms such as cough, chest pain, fever and haemoptysis. It is possible to identify the symptomatics by interviewing them during community health surveys. The symptom survey was carried out in 62 villages and 4 town blocks of Tumkur district in Karnataka as a sequel to an epidemiological survey undertaken to estimate the prevalence of tuberculosis. The data was collected through structured schedule. The interviewers were given the identification details of individuals having X-ray shadows suggestive of tuberculosis and an equal number of matched controls within 4 weeks of the survey. A total of 1752 persons were taken into the study of whom 875 had x ray shadows and 877 were normals. Of the total persons under study 89.7% were satisfactorily interviewed. It was observed that 42.6% of the total symptomatics gave history of one symptom at the first general question, 13% responded having symptoms after being asked specific questions. In conclusion a 42.6% affirmative response to the initial question of 'How is your health' is noteworthy that an investigator is acceptable health agency as the interviewee is willing to confide in him regarding his health problems. Additional number of persons responded to direct specific questions.

It must be pointed out that interview is a generic term applied to a tool that may be used for obtaining information through verbal communication. As a tool in surveys for screening for tuberculosis it is amenable to divese techniques and has great potentialities of being applied to different situations and various categories of respondents. Hence, it is necessary to identify the nature of data to be obtained and to decide on the technique that would be most suitable. Proper training, skill and supervision of the interviewer can obviate any possible bias and subjectivity that could vitiate an interview. As compared to many of the tools of social science research, the interview is simple, easy and amenable to being used in live situations. It is also of prime importance among populations for whom vocalisation is the most important medium of communication. Hence, in a community survey for the estimation of the prevalence of chest symptomatics the interview can be a valuable tool. It also shows that the interview is adequate as a tool of community survey in tuberculosis.

A study on awareness of symptoms of pulmonary tuberculosis and action taking was repeated in the 62 villages and 4 town blocks of Tumkur district of Karnataka after an interval of 12 years. In the earlier study, 2106 persons formed the study population. In the present study, 1752 were intaken to obtain a comparison of these 1752 intaken persons who were eligible for interview, 875 were X-ray positive and 877 X-ray normal (matched control).

The study showed that 95% of patients having radiologically active tuberculosis by both X-ray readers, 70% by one reader, 49.5% inactive by both readers, were aware of symptoms. According to the bacteriological status 79.5% had symptoms among those who were sputum positive by both microscopy and culture, 62.2% among those positive by culture alone and 73.7% among patients sputum positive by any method. Regarding action taking it was observed that 49.5% of the bacteriologically positive patients took some action compared by 70% of those found to have radiologically active disease by both X-ray readers. Thus action taking was higher among the latter category in both the studies. It may be due to the fact that extent of lesions are less advanced among those bacteriologically positive than among those who were in radiologically positive stage.

The findings of the study are similar to the earlier awareness study carried out in 1963 in the same area (Tumkur). This also indicates that in spite of having advantage of DTP for a decade actual and total benefits have not reached the people.

A longitudinal epidemiologic survey was carried out in Nelamangala taluk of Bangalore district since 1961, to find out prevalence of infection and disease of tuberculosis. During V round of the survey 1977, after 16 years of the first round, it was planned to study the awareness of symptoms and action taking of persons in the community where repeated surveys consisting of tuberculin, X-ray and sputum examinations had been carried out since 1961 and facilities for diagnosis and treatment were available since 1974. Fifty one persons aged 20 years and above, referred as X-ray positives were interviewed by social investigators on a structured questionnaire to elicit the awareness of symptoms and details of action taken to seek relief.

Of the 51 satisfactorily interviewed, 41 (80.4%) had symptoms suggestive of tuberculosis, of the 20 bacteriologically positive cases 19 (95%) were aware of symptoms suggestive of tuberculosis, thus registering a higher percentage of awareness than the X-ray positives. Of those with symptoms, 58.8% sought relief, many of them at multiple agencies such as Govt. hospitals and private practitioners, and some at tuberculosis hospitals, on being referred there. Most had obtained services free of cost and appreciated the available intrinsic benefits. Prior personal or family associations were the main reasons for seeking the services of private practitioners. Only 23% had gone to the nearest health facilities. Lack of proper facilities for good treatment and preference to be treated at urban centres, were the main reasons for not availing of the services at the nearest health facilities.

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.

National tuberculosis programme reaches people through PHCs and sub centres. A study was conducted to find out the perception of illness and utilisation of health facilities by the community. This study was conducted in a random sample of 48 villages selected according to Probability Proportioned to Size within 5 Kms of the selected PHIs in Kolar District using a Multi stage sampling technique. Information on socio economic status, availability of health services and their utilisation was collected. 13,323 individuals were interviewed. 706 were ill in a period of two months prior to survey. 71.3% had taken allopathic system of treatment. 69.1% had approached government hospital or PHC. 34 patients reported to have TB. All had attended either DTC or PHC.

The study indicated that morbidity was perceived much early and also followed by an action. Data indicates a high percentage of preferring allopathic system in general and from peripheral health centres and other Government hospitals in particular. Data indicates that in spite of overall backwardness of the study area and very limited economic resources people have utilised the PHC to the maximum. The reason could be either high acceptance of PHC or inevitability. But, there is an evidence of higher utilisation of family welfare and MCH services. The data shows all tuberculosis patients have had exposure to standard regimens, all of them have approached either PHC or DTC for treatment. This confirms the felt need oriented concept of National Tuberculosis Programme. Also high level morbidity among children below 4 years of age and action taken indicate an enhanced level of demand for health services.

In the BCG Mass Campaign low outputs and coverages of BCG vaccination done after tuberculin test were due to slowness of the campaign because of two visits to an area, the fear of two pricks and tuberculin tested absenting themselves from reading of the test. It was thought that if BCG vaccination could be given without prior tuberculin test and without causing any complications then the speed of work and outputs could be more than doubled and coverages improved appreciably. For this, the following three studies were carried out: In the first study 1,891 persons belonging to a rural population were randomly divided into four groups (i) those tuberculin tested and vaccinated, (ii) tested but not vaccinated, (iii) not tested but vaccinated, and (iv) neither tested nor vaccinated. Induration site of tuberculin test and vaccination were read on the 3rd, 6th and 90th day. Later on, another tuberculin test was done on the 90th day and read 3 days later. Both axillae were examined on 0, 14th and 90th day and X-ray pictures were taken on 0 day, 90th day and after one year. Tuberculin indurations on 3rd day were compared with BCG induration on 3rd, 6th, 14th and 90th day. Majority of tuberculin reactors had large BCG indurations upto 14th day. By 90th day very few persons have large indurations left. Among non-reactors also large BCG reactions were seen in 25%-53% of the persons. There were no differences as regards to the size of lymph nodes (regional reactions) between reactors and non-reactors; neither was there any evidence of exacerbation of existing disease nor any flaring up of dormant foci (Primary complex) in the form of new disease as shown by X-ray.

In the second study out of 1,520 persons from 4 villages, 1,186 were both tuberculin tested and simultaneously vaccinated. Examination of local reactions daily from one to nine days, on 19th and the 29th day, confirmed the findings of first study with regard to the local reactions. In this study neither axillae were examined nor X-ray pictures taken. In the third study, influence on acceptability of direct BCG vaccination due to large local reactions was tested. Twelve villages in Gubbi taluk of Tumkur district were taken in pairs. Vaccination of 2nd village of each pair was done after 1-4 weeks of the vaccination in lst village to observe the influence of BCG reaction on the people. Vaccinations were given to 5363 (64.2%) persons from the total registered population with Madras liquid vaccine. The large local reactions showed no adverse effect on the acceptability of BCG vaccination in the neighbouring villages, rather a slight improvement in BCG vaccination coverages with time was seen.

BCG vaccination is being conducted as a mass campaign. It is difficult to maintain a high coverage of the population at risk i.e., new borns. This can best be done by integrating the BCG vaccination services with the general health services. The present investigation was planned to study the feasibility of routine BCG vaccination of the new borns by the Primary Health Centre personnel using the normal records maintained by them. In a rural population of 33,128 persons (1971 census), served by PHC Bettahalasur of Bangalore district, BCG vaccination was administered to 0-15 months old children by 2 Block Health Workers (BHWs) and 3 Auxiliary Nurse Midwives (ANMs) after training them for about 3 weeks. They used a compact specially designed BCG kit and employed a conventional intradermal technique for BCG vaccination. Routine work was not to be disturbed in any way. Each worker prepared a list of children eligible for BCG vaccination from the register of unprotected children and updated the list for those not found registered. National Tuberculosis Institute (NTI) field staff registered a sample population, allotted to each worker for estimation of eligibles. Three months later they also examined BCG vaccination lesions in a sample of children. BHWS and ANMS were interviewed by a medical officer from NTI regarding their opinion on integrated work.
The findings showed that the ANMS and BHWS had already registered nearly 50% of the new borns in their records with variation in registration from 21 to 80% by the field workers; ANMS understandably having registered lesser numbers. All of them were, however, able to update the registrations to a level of 82%. They could pick up the BCG vaccination technique easily. Of the total eligibles, ANMS and BHWS could contact 86.4% and vaccinate 77%; remaining 23% either refused or were excluded from vaccination. In the total eligibles registered, however, the vaccination coverage was 66.6%. Of the children reported vaccinated, 96% had evidence of BCG vaccination indicating a high degree of reliability of reporting. The opinion of all the 5 field workers on integration was favourable. All the ANMS and BHWS workers, on interview, stated that they had done BCG work without detriment to their other duties and would be easily able to do so in future. The field workers can accumulate the new borns for a year and vaccinate them during a month. This has mainly operational advantages including less vaccine wastage. For urban areas a different operational design with the same principles may become necessary.

After the introduction of direct BCG vaccination, assessment of post-vaccination allergy and information about prevalence of infection could not be obtained. Few methods were tested i.e., i) retesting of persons with 0-13 mm reaction at site of vaccination on 4th day of vaccination, ii) retesting of all vaccinated persons of age 0-10 years. It is not only necessary to find out the size of BCG lesion that could separate them but also the day after vaccination on which the tuberculin reaction size best correlates with the BCG vaccination size. With this in view, two studies with regard to direct BCG vaccination done in India have been examined further. In Study I, 816 eligible persons were tested with 1 TU RT 23 read on 3rd day and vaccinated with either Indian or Danish vaccine. The vaccination lesions were examined on the 3rd, 6th and 90th day of vaccination. On the 90th day post-vaccination tuberculin test was done and read on 3rd day. In Study II, a total of 691 who had no previous BCG scar were simultaneously tuberculin tested with 1 TU RT 23 and vaccinated with either Indian or Danish vaccine. The BCG lesions were examined every day and on 39th and 90th day.

The correlation of pre-vaccination tuberculin test and BCG lesion size showe d that sixth day in first study and fifth day in second study was the highest. Tuberculin reaction size of 10 mm or more correlated well with 14 mm or more induration size of BCG in classifying the persons as infected and non-infected. Correlation between the size of BCG scar at 3 months and size of pre-vaccination tuberculin reaction was poor. Considering the two studies together vaccination induration of 14 mm or more on 5th or 6th day appears to be the best criterion for demarcating the infected from non-infected. Some other choices are 12 or 14 mm levels on 2nd day, 10 and 12 mm levels on 5th day and 10 mm levels on 8th day seems to be nearly as good and operationally useful.

A BCG Vaccination induration size of 14 mm and above between 5th and 6th day of vaccination, for all practical purposes may be considered satisfactory for demarcating persons infected with M.tuberculosis from those non-infected. It can be concluded that estimation of prevalence of infection, when BCG vaccination is given to all without prior tuberculin testing, can be made on the basis of BCG vaccination induration size of 14 mm or more.

A study was conducted to evaluate the usefulness of pyruvate medium for isolation of M.bovis from human material and additional yield of M. tuberculosis resistant to INH. Specimens from both rural and urban populations were included for this study in order to understand the problem in both the situations. There were two studies in progress at the National Tuberculosis Institute when pyruvate media slopes were introduced for culture purpose. One study was an epidemiological survey; 2518 sputum specimens received from 51 villages covering a population of about 32,300 were used. The specimens were collected from persons aged 5 years and above showing abnormal shadow on X-ray. The other study was conducted in collaboration with the State Tuberculosis Centre, Bangalore; 1204 sputum specimens were received from out patients attending the centre. In addition to LJ medium, pyruvate medium was used for isolation purposes. Identification and sensitivity tests were done on positive cultures as per routine. In all, 129 cultures of tubercle bacilli were isolated from 2118 specimens belonging to study 1 and 398 from 1204 specimens belonging to study 2. The number of cultures contaminated were 253 and 35 respectively. No M.bovis was isolated in either study. There were 24 and 23 cultures resistant to INH among those isolated from LJ and pyruvate medium respectively. Thus, no increase was observed in the isolation of INH resistant strains using pyruvate medium.

Hence, no benefit was derived by using this medium over and above what was obtained from plain Lowenstein Jensen medium in both the situations.

The results of the tuberculosis prevalence surveys carried out in 59 villages of Tumkur district, Karnataka in 196l before launching the District Tuberculosis Control Programme (1964) and the second one, nine years after the introduction of the programme (1973), were compared.

The prevalence rates in both the surveys were similar viz. 0.41 per cent in 1961 and 0.44 per cent in 1973 indicating the poor impact of the programme. The present analysis provides information on long term cumulative performance of the District Tuberculosis Programme (DTP) in diagnosing the cases detected in a prevalence survey at a point of time. Of the 70 cases diagnosed during I survey 12 (17.1%), and of 121 during II survey 20 (16.5%) were diagnosed by the District TB Programme independently over a total period of 19 years. Of the 12 DTP cases of I survey, 1/3rd were diagnosed by DTP within 3 years and the remaining were distributed over a period of 12 years. Similarly, of the 20 cases of II survey, 45% were found within 3 years after the survey and 25% within 3 year periods immediately prior to it. In subsequent years, Case-finding activity about these prevalence cases was erratic and at much lower rate. There was no difference between smear positive and culture positive survey cases with respect to their diagnosis by DTP. The changes brought about in the prevalence of cases from year to year by death, cure, incidence and performance of DTP, in diagnosing such prevalence cases, could not be studied from the available material. Under reporting of the diagnosed cases and missed diagnosis are attributed to be the main factors for poor performance of the DTP.

As a part of the supervised field training of the students of health education from Rural Health Training Centre, Gandhigram, Tamil Nadu, a pilot project of short term intensive health education was undertaken at 11 selected villages under Primary Health Centre (PHC), Hesarghatta. The objectives were to measure the impact of an intensive health education effort in increasing the attendance of patients with symptoms suggestive of pulmonary tuberculosis at a PHC and to study the impact of health education in terms of increase in knowledge and change of attitude of the people towards the PHC. For participation of the community all the three health education approaches viz., individual approach, group approach and mass approach were planned along with audio visual aids as and when required. Application of a specific approach depended on the level of awareness about tuberculosis and the availability of services which was measured by a base line survey conducted in the selected villages.

As expected this short term intensive health education has shown that the knowledge on tuberculosis in the population increased, following it. When it was measured by the yardstick of increase in the proportion of out patients with chest symptoms, attending the PHC, no significant change was noticed during the period of observation. The likely reason could be that it was too early to measure the effect of health education within a period of 6 weeks. In this project the intensive health education work was done almost continuously for a short time which was probably not appreciated by the people. Though in all the villages following the health education programme, the people had understood the importance of getting the chest symptoms examined to rule out tuberculosis, they have not approached the PHC for the same. The other possible reason could be that the people are not satisfied with the services provided by the PHC. It goes without saying that when the services provided by the PHC itself are not upto the expectation of the people, the outcome of health education could only be