Limitations of a single X-ray picture for locating and interpreting shadows in the chest had been studied earlier. In order to reduce these limitations, it was suggested that two pictures of each person be taken where the second picture was to be taken after a vertical displacement of X-ray tube, up or down by about 4 to 5cms. The advantages of taking two pictures simultaneously as compared to a single picture have not been studied so far. Two mobile X-ray units each with an odelca camera were alternated for the single and double picture examinations. A total of about 2,000 persons were X-rayed and were read independently by 3 readers. A spot sample of sputum was collected 3-4 days later from persons with abnormal X-ray shadows and was examined by direct smear microscopy.

Comparison of the readings of the two sets of pictures did not show a better agreement between different (inter- individual) readers or between two different readings of the same reader (intra-individual) when the two picture technique was used. The X-ray cases detected by double picture only by any one reader were not confirmed, more often than those detected by single picture only. The X-ray pictures of the bacillary cases were also not interpreted more often as active tuberculosis by the two picture technique. It was concluded that the double picture technique does not offer any advantage over the single picture technique.

The incidence of infection with mycobacterium tuberculosis is an index of the risk of infection to which a community is exposed. An accurate estimation of incidence rate is of considerable importance in understanding the epidemiology of tuberculosis in organising control measures. A new method of estimating incidence of infection is discussed. The material from 3 studies of National TB Institute has been utilized. Study I: is a part of a survey of a random sample of 134 villages. No previous tuberculin testing or BCG vaccination had been carried out in the area, but each person was examined for BCG scar in order to exclude persons vaccinated probably from other areas. After a complete census, a Mantoux test with 1 TU of PPD RT 23 with Tween 80 given on two occasions (Round I and II). Those with reaction of 13mm or less at Round I were offered a test with 20 TU with Tween 80 within a week of 1 TU test. The interval between the rounds was about 18 months. From the analysis of the data from the first 50 villages for which complete information for both rounds was available, it was seen that there was a general increase in the size of reactions elicited in the second round. Study 2: tuberculin testing was carried out with 1 TU and 20 TU among selected ‘control’ groups which provided the data regarding the “enhancing of tuberculin allergy” seen in repeat tuberculin tests. Study 3: in the course of the longitudinal “survey reader assessments” were carried out periodically to judge the standards of the tuberculin test readers. Inter & intra-reader comparisons were made. The findings have been used to estimate the magnitude of reader variation. The data was also used to study variations in the technique of testing and reading.

It was estimated that on an average inter & intra-reader variations between the rounds were unlikely to exceed 6mm or more in more than 5% of the observations. The reading errors have an equal chance of being positive or negative except at extreme ends of the distribution where zero readings of Round I can only show an increase, and the very large reactions had a greater chance of showing only a decrease at a subsequent round. The study mainly concerns with the problems of estimating the incidence of tuberculous infection in a community. Calculations based on age-specific prevalence rates or on rates of tuberculin conversion or both subject to gross error, leading to unreliable epidemiological conclusions. For estimating the newly infected, a new approach has been suggested based on the drawing of a curve for the distribution of differences in reaction size from one round of tuberculin testing to another. It is assumed that if new infection causes a distinct rise in the degree of tuberculin sensitivity which is greater than the combined rise due to enhancement and reader variation, the distribution of differences between the rounds should indicate the newly infected. It is shown that the newly infected probably constitute a homogeneous group with an increase in mean reaction size of about 24mm and standard deviation of 4mm. Accordingly, 98% of the newly infected show an increase in reaction size of 16mm or more.

Tuberculin tests repeated after an interval of time, at a different site have been reported to elicit reactions larger than the first test. A study was undertaken where reactors of 13mm or less to 1 TU have been tested with 20TU for the study of low grade reactions. Study was carried out in a previously untested and unvaccinated rural population (Longitudinal Survey), where only about 25% of the population showed 14mm or more to 1 TU and the remaining about 60% showed 10mm or larger reactions to 20 TU. These results confirm the high prevalence of non-specific allergy in the area.

It was found that a tuberculin test does enhance the allergy elicited by a subsequent test. The enhancing effect is associated with the initial allergy i,e., 8-13mm to 1 TU tuberculin, especially those elicited by a 20 TU test, increase being almost confined to those with 10mm and larger reactions to 20 TU. The enhancing effect increases with increase in age especially among those with 10mm or bigger reactions to 20 TU. It is possible that the enhancing effect is more in communities with high prevalence of non-specific allergy.

Studies on the distribution of tuberculous infection and disease in households have mostly been restricted to the examination of contacts of known cases. Clinical experience has lead to a strong belief that tuberculosis is a family disease and contact examination is a “must” for case-finding programmes. A representative picture of the distribution of infection and disease in households can be obtained only from a tuberculosis prevalence survey.

This paper reports an investigation, based on a prevalence survey in a rural community in south India. The survey techniques and study population have been described in an earlier report. Briefly, the defacto population was given a tuberculin test with 1 TU of PPD RT 23 with Tween 80 and those aged 10 years and above were examined by 70mm photofluorography. All the X-ray pictures were read by two independent readers. Those with any abnormal shadows by either of the two readers were eligible for examination of a single spot specimen of sputum by direct smear and culture. The defacto population numbered 29,813 and tuberculin test results were available for 27,115. After excluding BCG scars, the study population of 24,474 was distributed over 5,266 households which were further classified as “bacillary case household” with atleast one bacteriologically confirmed case, “X-ray case household” with atleast one radiologically active case but with no bacillary cases and ‘non-case household’ with neither a bacillary nor an X-ray case. Total bacillary cases were 77 and were distributed in 75 household. 74 households had one case each and one household had 3 bacillary cases.

The findings of the study have thrown considerable doubt on the usefulness of contact examination in tuberculosis control; (1) over 80% of the total number of infected persons, in any age group, occurred in households without cases, (2) cases of tuberculosis occurred mostly singly in households, and the chance of finding an additional case by contact examination in the same household is extremely small, (3) a common belief has been that prevalence of infection in children in 0-4 age group is a good index of disease in households, but in this study about 32% of households with cases of tuberculosis had no children in this age group, (4) in houses with bacteriologically confirmed case only 12% of the children in 0-4 age group showed evidence of infection, a possible explanation of such a low intensity of infection could be that there is resistance to infection. It is well known that some children even after repeated BCG vaccination do not become tuberculin positive. It is felt that a large number of children do inhale tubercle bacilli, but a primary complex does not develop or even if it develops, the children remain tuberculin negative. A hypothesis has been made that in addition to resistance to infection, there is something known as “resistance to disease”. Otherwise, it is difficult to explain why under conditions of heavy exposure in infection, only some individuals develop evidence of infection and very few develop disease thereafter.

Generally there is no acceptable definition of the term “case of pulmonary tuberculosis”, although such a definition is of fundamental importance both in clinical medicine where results of various chemotherapeutic regimens are compared, as well as for the comparison of different epidemiological data. The main purpose of this paper is to focus attention on the difficulties of defining a case on the basis of bacteriological examination, X-ray examination and tuberculin test. Data from two successive prevalence surveys in a random sample of 134 villages in Bangalore district with a population 70,000 have been utilized to illustrate some of the difficulties in defining a “case” of pulmonary tuberculosis for reporting the prevalence or incidence of the diseases. The entire population was tuberculin tested with 1 TU RT 23 with Tween 80 at both rounds and those 5 years of age and older were examined by 70mm photofluorogram. The sputum specimens (spot and overnight) were collected from those with any abnormality on X-ray as recorded by either of the two independent readers. Both the specimens were examined by fluorescent microscopy and Ziehl-Neelsen technique and by culture.

Analysis of data has shown that the term “a case of pulmonary tuberculosis” does not represent a single uniform entity, but embraces cases of several types, differing considerably in their tuberculin sensitivity, results of X-ray and sputum examination, in the reliability of their diagnosis and mortality experience. The status of cases found at initial and subsequent surveys showed changes with time, and such changes show considerable differences for the various types of cases. It was felt that a single straight-forward definition of a case was not possible to suit all situations. One has to use more than one definition. Although theoretically, finding a single bacillus in sputum should be adequate proof of pulmonary tuberculosis, it was shown that finding of a few bacilli (3 or less) was very often due to artifacts and should not be the basis for a diagnosis. It has also been found that positive radiological findings, in the absence of bacteriological confirmation, indicate only a high risk of the disease and not necessarily pulmonary tuberculosis. Direct microscopy appears to be a consistent index of disease but in community surveys has the limitation of missing a substantial proportion of cases and of adding some false ones.

In view of the difficulty of providing a single definition of a case of tuberculosis, four indices have been suggested. (1) Cases definitely positive by direct smear; (2) Cases definitely positive by culture; (3) All cases positive by culture (including less than twenty colonies); (4) Sputum positive cases which are radiologically active. Each of these could be used for different situations. However, it was concluded that, there seems to be no option but to use more than one definition for assessing the prevalence and incidence of disease.

Prevalence surveys are useful for estimating the tuberculosis problem in different countries. Three techniques are commonly used in surveys, tuberculin test, mass miniature radiography and sputum examination. Each has its own limitations. A limitation of sputum examination is that all the sputum positive cases in the community cannot be diagnosed when only one sample of sputum is examined from each eligible person. Multiple sputum examinations are not often possible under field conditions of surveys covering the whole community. It would be worthwhile to have some idea of the extent of under-diagnosis in sputum examination. For this purpose, during an epidemiological survey, four specimens of sputum were collected within seven days of X-ray examination from each person with an abnormal chest X-ray in 30 villages of a district of south India. Each specimen was examined by Fluorescent Microscopy (FM), Ziehl Neelson (ZN) technique and culture.

There were 34 culture positive cases among 2,164 persons for whom all the four culture examination results were available. Of them, 21 (62%) were found positive on one specimen. The second specimen increased the positivity to 32 (95%). Thus, for detecting both smear and culture positive cases two specimens are adequate. A third specimen is helpful for detecting cases positive by culture alone. An estimate of prevalence obtained from one sputum specimen can be estimated for the prevalence obtained from many specimens by applying correction factor of 1.67 and estimates based on two specimens by applying 1.26. Of the remaining 37 smear positive cases detected by one specimen, 20 were smear positive and culture negative. Of the remaining 17 smear positive and culture positive, 14(82%) were detected by one smear examination only.

ZN positives not confirmed by culture (mostly with less than four bacilli reported in the smear) increased from 7 from the first specimen to 18 from all four specimens, while positives confirmed by culture method showed only a marginal increase from 13 to 15. FM did not have this disadvantage as only two were culture negative among the 18 smear positive results by FM method. Examination of two specimens by FM detected about 95% of cases demonstrable by this method. But with the ZN technique additional specimens may add more “false positives”. Thus, for detecting cases both smear and culture-positive two specimens appear adequate. A third specimen is helpful for detecting cases positive on culture only.

The prevalence and incidence rates of tuberculous infection and disease in the community are known in the age group 10 years and above from several surveys carried out so far. The present paper provides various parameters of tuberculosis in particular in the pediatric age group. A random sample of 119 villages in 3 taluks of Bangalore district were surveyed 4 times from May 1961 to July 1968 at intervals of 18 months, 3 years and 5 years of the initial survey. Tuberculin test was done for the entire available population with 1 TU PPD RT 23 with Tween 80, and 70mm X-ray for all available persons aged 5 years and above. Two samples of sputum were obtained from the X-ray abnormals, and examined by smear and culture.

It was found that prevalence of infection increased with age from 2.1% at 0-4 year age group to 16.5% at 10-14 year age group, compared to 47% at 15 years and above age group. Prevalence of disease in 5-14 year age group was considerably lower than in age group 15 years or more. Tuberculosis morbidity increased with the size of tuberculin reaction and it was high among children with reaction 20mm or more. Incidence of infection increased with age from 0.9% per year in age group 0-4 years to 2.8% per year among that of 15 years and above. Incidence of disease also showed the same phenomenon-, rising from 0.5% in age group 5-9 to 4% per year in the age group 15 years and above. There were 10 sputum positive cases in 5-14 years of age in first survey, of them, 8 became negative and one died. While from among 152 cases in 15 years and above age group, 48 became negative, 72 died and 32 remained positive. The fate of cases of pulmonary tuberculosis in 5-14 years age was not as serious as in 15 years and above age group. The survey had no means of examining miliary and meningeal tuberculosis.

Children as well as adults with larger reaction of 20mm or more to tuberculin test had higher mortality. This could be considered due to tuberculous infection after taking into account death due to non- tuberculous reasons in both the infected and uninfected groups. Use of chemoprophylaxis might be considered for those who give history of contact with open cases and have tuberculin reaction size 20mm or more.

Data from 62 randomly selected villages in a district of south India, which formed part of a prevalence survey carried out by the National Tuberculosis Institute, Bangalore, during 1960-61, has been made use of. The survey covered 29,813 persons in 5,266 households. There were 70 cases with bacilli demonstrable either in smear or culture and 300 suspect cases. Using the village map (prepared by survey staff), ‘case clusters’ were formed first, with each case household as nucleus and adjacent households within a maximum distance of about 20 meters on either side of the case households. Households closest to the nucleus household on either side have been called as 1st neighbourhood and those coming next in proximity on either side as a 2nd neighbourhood and so on. The case household and its four neighbourhood together was called a cluster. If another case household was found within 4th neighbourhood of the first case the cluster was extended by including the 4th neighbourhood of the new case also. Such clusters were called composite case clusters and clusters with only one case household as simple case clusters. Similarly, suspect case clusters were formed and differentiated as simple suspect clusters or composite suspect clusters. Further, to serve as a control group, non-case clusters were constituted from a systematic sample of 10% households that were not included in case or suspect case clusters.

Out of 60 case clusters formed, only 7 have multiple cases showing that there was no evidence of high concentration of disease in case clusters. While the percentage of child contacts (0-14 years) infected was considerably higher in case clusters (25.8%), there was not much difference between suspect case clusters (14.9%) and non-case clusters (9.8%). Similarly, there was not much difference between simple and composite clusters. Infection among child contacts was higher in case households as compared to their neighbourhoods. To get some idea of the zone of influence of a case or suspect case, prevalence of infection was studied for 10 neighbourhoods, in simple clusters to avoid the influence of multiple cases. It appeared that the zone of influence of a case may extend at least upto the 10th neighbourhood. It was also noted that there was very little difference between zones of influence of suspect cases and non-cases. Case clusters in which the nucleus case had shown activity of lung lesion (evident on X-ray reading) or had cough showed significantly higher infection among child contacts. Clusters around cases positive on both smear and culture did not show higher infection than those around cases positive on culture only. (This may be due to sputum examination of single specimen only).

Out of the total infected persons in the community, only 2% were in case households and 7% in suspect case households, over 90% being in non-case households. The zone of influence of a case extending at least upto the 10th neighbourhood and the overlapping of such zones of influence of cases, present and past, seems to be the most probable explanation for the wide scatter of infection in the community. Prevalence of infection among child contacts was definitely higher in case clusters. But, the significance of this could be understood only from a study of the incidence of disease during subsequent years in different types of clusters. It is significant that only 10% of the total infected persons in the community were found in case clusters. The case yield in general population, cluster contacts, household contacts and symptomatics attending general health institutions have been also compared. The case yield in the last group (10%) is much higher than the case yield from both types of contacts (0.7% and 0.6%) which where only slightly higher than the case yield from the general population (0.4%).

Available data from longitudinal study (1961-68) from several different situations have been reviewed to understand the significance of patients showing radiological evidence of pulmonary tuberculosis without bacteriological confirmation. SITUATION IN GENERAL POPULATION: Few of the smear negative but X-ray active tuberculous patients (suspect cases) found in a survey of rural population done by National TB Institute, were culture positive (7-10%). On follow up for 18 months, only 3% of them became culture positive under conditions where intervention with specific treatment was absent or minimum. It is thus concluded that most of the cases diagnosed as active tuberculosis on the basis of single X-ray are not likely to be cases of tuberculosis. SITUATION AMONG SYMPTOMATICS ATTENDING HEALTH INSTITUTIONS: Data from the State TB Demonstration and Training Centres (STDTC) and the District Tuberculosis Programmes (DTP) have been presented. The New Delhi Tuberculosis Centre records (1970) show that only 27% of microscopy negative radiologically positive patients were confirmed on culture. For Bangalore and Agra STDTC, the proportions so confirmed were 20% and 25% respectively. It has been calculated that in the DTPs, not more than 30% of the microscopy negative radiologically positive patients could be the real cases of tuberculosis. In the DTP situation not more than 10% of the suspect cases may develop bacteriologically confirmed disease. Thus, not many of the suspect cases could be real cases of tuberculosis either on the basis of confirmation by culture or on the basis of development of bacteriologically positive disease in future.

Are the cases diagnosed ‘early’ by radiology? The hypothesis that X-ray discovers cases in the early stages has not yet been put to a scientific test. Further, the large differences even between experienced readers in interpreting X-ray shadows, render the method of X-ray diagnosis questionable. Is anti tuberculosis treatment of suspect cases warranted? The possible advantage of considering treatment of suspect cases as chemoprophylaxis has to be weighed against conservation of resources for treatment of infectious cases and the possible harmful effects of anti TB drugs to persons who are not suffering from tuberculosis.

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.

Examination of only one sputum sample cannot detect all the sputum positive cases in the community. To obtain better estimates of the prevalence of bacteriologically confirmed disease in the community, a study was conducted to find out the additional yield of cases through collection and examination of eight sputum specimens and also in order to work out correction factors for estimates based on one or two sputum samples, as collecting multiple sputa is very difficult. The study was carried out in 77 villages in Nelamangala Taluk of Bangalore. In all, 5826 persons were referred for sputum examinations.

Results of all the eight culture examinations were available for 2973 (51% of the eligibles). Of these 64 persons were positive by culture of atleast one specimen. Each of the eight specimens has the chance of detecting a case and any one of them could be considered as first or second specimen etc. To overcome this difficulty 80 permutations were randomly chosen out of the total 40,320 permutations possible. Cases from first specimen and additional cases from subsequent specimens were calculated through four mathematical equations. The first equation namely Y = KXm (28.66 x-1.40) has been considered as providing the best fit to the observed data. On the basis of this equation it appears that additional positives could be obtained upto the 1Oth specimen. Out of 64 culture positive cases, only 72% of positives could be detected by first two samples. To get about 95% of the cases, it is necessary to examine at least six specimens from each individual. Multiple samples are rewarding for detecting even high grade cultures.

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.

Some of the parameters relating to duration of infected status and incidence of disease have been measured by analysing the data collected from the five year study. Between 1961-68, 119 villages in Bangalore district with total average population of about 62,000 were surveyed at intervals of 1, 3 and 5 years from the first survey. All persons were tuberculin tested with 1 TU RT 23 and those aged 5 years or more were X-rayed. Sputum of those persons showing any X-ray abnormality were collected and examined for AFB. Persons with X-ray abnormality but bacteriologically negative or with normal X-ray in all the preceding surveys, and who became culture positive with X-ray abnormality in the current survey were termed as "New cases". New cases who had shown 10 mm or more reaction to 1 TU RT 23 at I Survey were considered infected previously. New cases, tuberculin negative at I survey but who showed an increase of 16 mm or more between two consecutive surveys were considered infected midway between the two surveys.

Of the 42 new cases diagnosed from among the newly infected during 5 years, 81% came from those infected within one year. Incidence rate of cases among those who were infected within one year was about 5 times more than those infected earlier than one year. Incidence of cases steadily decreased with the increase in the duration of infection. Further, it was found that one fourth of all newly diagnosed cases came from the newly infected persons. However, the size of the pool of previously infected persons in a community being much larger, at least 72% of the new cases came from the reservoir of previously infected persons. The incidence of disease among the newly infected was almost the same in the three age groups i.e., 5-14, 15-34 and 35 years or more. But, the ratio of the incidence rates for the newly infected and the previously infected decreased from 13 for the age group 5-14 to 3 for the age group 35 years and above. In other words, the incidence of disease among the newly infected in the age group 5-14 was thirteen times more than for the previously infected in the same age-group whereas in the age-group 35 years and above, the incidence among newly infected was only thrice that among the previously infected.
Out of the 160 new cases diagnosed during the three repeat surveys, 21 per cent cases came from among those who were infected on the average for one year or less. This is almost in conformity with the hypothesis that one-fourth of all new active cases come from new infections less than a year old.

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.

The study was undertaken among 22,957 persons belonging to 55 randomly selected villages of Nelamangala taluk of Bangalore district in 1975, to find out precise estimates of prevalence of bacillary disease. Symptom screening was done by well experienced social investigators, according to a brief interview schedule. Sputum was collected from all above the age of 5 years reporting chest symptoms for seven or more number of days during the previous two months. Within two weeks after symptom questioning, all were tuberculin tested and all 5 years and above were X-rayed. Additional sputum collection was done for those asymptomatics who had abnormal shadows in their chest X-rays.

The overall prevalence rate of culture confirmed bacillary cases by symptom and/or X-ray screening was 0.32 percent. Same prevalence was seen with X-ray alone also. But the overall prevalence rate based on symptom screening alone was 0.21 percent which is significantly lower than that of symptom and/or X-ray screening, or X-ray screening alone. The prevalence rates by age and sex based on symptom screening were about two-thirds that of rate based on X-ray and/or symptom screening. Hence to obtain prevalence rate according to X-ray and/or symptom screening, a correction factor of 1.52 should be applied to the prevalence rates obtained by symptom screening alone. This correction factor is fairly good for most of the age groups. It was also estimated that the cost of surveying the population by symptom screening alone is about half that of surveying the population by X-ray screening.

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.

The Health Intelligence System has to provide information for the planning, monitoring and evaluation of the Health Services which are provided by the Health Care Delivery System in the country. The Health Intelligence System should also be in a position to provide information on the health needs and demands of the community so that the Health Care Delivery System can plan to meet the unmet demands and needs. Information available is quite often incorrect, incomplete and out dated. Appreciable improvements can be effected only on the basis of a critical appraisal of the system. Some of the important reasons are lack of training, aptitude and sense of involvement in the work by the staff, improper reporting proformae, enforcement of targets, absence of discrimination between routine and special health intelligence, quantitative and qualitative data and lack of systematic & regular supervision by health administrators particularly at the district level. Suggestions for improvement are better utilization of collected data, simplification of proformae, adequate training to the staff in health intelligence, realistic variability of targets, integration of health intelligence for various components of the health care delivery system, bifurcation of data into two i.e., simple routine use and for use for special purposes and regular and systematic supervision and make suggestions for taking top level decisions. The major gaps and other problems listed in this paper and the suggestions made to overcome these are of such nature that these have to be considered at top levels and decisions taken, preferably on the basis of the observations and recommendations of a study group of experts set up for the purpose. Until some basic changes are made, the Health Intelligence System will continue to be thoroughly inadequate for proper planning, monitoring and evaluation of the Health Care Delivery System.

In the formulation and evolution of a National Tuberculosis Programme some assumptions are made which require to be tested under the normal administrative set up with minimum interference by the investigating team. The objectives of the study were to understand some operational aspects of Case-finding in the Peripheral Health Institutions (PHIs) in an integrated programme. First, what is the frequency of persons showing symptoms suggestive of pulmonary tuberculosis among the normal out patients attendance (OPA), how many cases can be found by direct microscopy of sputum of those symptomatics, what will be the workload of TB Case-finding at a PHI and, what proportion of symptomatics will be willing to and will actually attend the District TB Centre (DTC) when referred there for X-ray examination. The study was conducted in a district with a population of 1.5 million having one DTC and 55 PHIs. 15 PHIs were selected on the basis of stratified random sampling. At each PHI an National Tuberculosis Institute (NTI) investigator worked for a period of one month. All new out patients were questioned for symptoms (non- suggestive and suggestive) and any patient with chest symptoms mainly cough for more than one week fever, chest pain and haemoptysis was subjected to a sputum examination and also referred for X-ray examination at the DTC.

It was found that 381 (2.5%) of the 14881 total new out patients of all age groups complained of cough for 2 weeks and more. From these chest symptomatics, 11% were new cases of pulmonary tuberculosis. When the symptomatics were referred for X-ray examination, although 66% agreed to go for X-ray to DTC but only 16% (of the total referred) actually went for X-ray. Each PHI had to examine only one or two sputum specimens per working day. As the study was conducted in a representative sample of PHIs for a representative duration of time, the material permits the estimation of the potential yield of cases in a District TB Programme (DTP) during a period of time (say one year). It was estimated that about 45% of the total estimated prevalence cases in a district can be diagnosed in a DTP during a period of one year, if all PHIs function according to the programme recommendations. The workload due to tuberculosis Case-finding is small and can be managed with the existing staff and Case-finding by direct smear examination of sputum at the PHI has to be relied upon.

This investigation was to find out the drug consumption among tuberculosis patients put on domiciliary self administered chemotherapy, in terms of proportion of patients that make various levels of drug collections and proportion among them that consume drugs at different points of time during the course of treatment. In all, 816 tuberculosis patients aged 5 years and above residing in Bangalore city were admitted to the study. They were randomly divided into 6 groups at the time of inclusion into the study, for examination of urine samples for the presence of INH and PAS. One surprise urine sample was collected from each patient at the pre determined time after the drug collection. The samples of urine were collected from one group at first month, another at second month, third at fourth month, fourth at sixth month, fifth at ninth month and sixth at twelfth month of treatment. Urine samples were collected within 33 days of drug collection for the month because the drugs were supplied at a time for the said period. Urine specimens were examined for the presence of drugs or their metabolites. For INH, NM test & acetyl INH test and for PAS, ferriechloride and case test were performed. The drug collection was judged on the basis of treatment record and its consumption on the basis of results of urine examination.

Of the total patients included in the study, 54% made 10 or more drug collections over a period of 15 months. The initial radiological or bacteriological status or severity of disease did not influence the drug collection; however smaller proportion of old persons in both sexes collected the drugs for 10 months or more. Urine specimens of 71% of patients who had collected drugs were positive for INH on any one day. Bacteriological quiescence was obtained among the 82% INH sensitive patients who had made 10 or more collections. The above findings suggest that the patients who collect drugs also consume with fair amount of regularity and achieve a high degree of bacteriological quiescence.

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.

The conventional methods of assessment of post-vaccination allergy by doing tuberculin testing among the vaccinated group are inapplicable in case of BCG vaccination without prior tuberculin test (Direct BCG). Because of obvious technical and operational advantages of direct BCG vaccination a search for a method of technical assessment of BCG vaccination is important. Hence, a study was carried out by the BCG Assessment Team of National Tuberculosis Institute in Tumkur district of Mysore state where Mass BCG Campaign was going on. Four groups of persons aged 0-20 years, each group belonging to two BCG Technicians area and vaccinated one day prior to visit of assessment team, were randomly selected. Besides, persons (0-20 years) from 2 unvaccinated villages of adjacent area were included as control groups. All persons were registered simultaneously tuberculin tested with 1 TU RT 23 and 5 TU RT 22 within 24 hours of BCG vaccination (for pre-vaccination allergy) and retested with tuberculin 5 TU RT 22 at the end of 3 weeks and 3 months (for post-vaccination allergy). The four vaccine groups were vaccinated with vaccine batch Nos. 977, 978, 981 and 984 respectively. Classification of the directly vaccinated persons into previously infected and non-infected by tuberculin test administered within 24 hours of vaccination and about 12 weeks later, elicitation of post-vaccination allergy only among the non-infected, has been considered as the Reference Test for judging the suitability of other methods of assessment studied. The main findings are: (1) The Reference Test showed that the four batches of BCG vaccine used had induced varying levels of allergy. (2) Assessment based on the mean size of post-vaccination reactions among 0-4 years age group, which consists predominantly of previously non-infected persons, showed a different pattern of differences between the four batches of vaccine as compared to the Reference Test. Moreover, to get adequate number of children aged 0-4 years, it will be necessary to cover a comparatively large population. (3) The method of using the mean size of post-vaccination reactions among those classified as non-infected on the basis of vaccination reactions of size 0-13 mm at the site of BCG vaccination on the 4th day of vaccination showed results similar to the Reference Test. But this method has only a marginal operational advantage over the Reference Test. (4) Using size of induration at the site of vaccination on 21st day of vaccination did not give the same results as the Reference Test. Operationally this method would have been most suitable as it involved only one visit to the group. (5) Differences between mean size of post-vaccination tuberculin reactions among directly vaccinated persons and mean size of (natural) allergy in reactors among neighbouring unvaccinated areas showed the same results as the Reference Test. This method has the operational advantage but needs further investigations. (6) Tuberculin testing of all directly BCG vaccinated persons including the natural reactors about 12 weeks after vaccination compared favourably, with the reference method, as the tuberculin reactors contributed less than 1 mm over and above the allergy in the vaccinated non-reactors . This method would be useful when rate of tuberculin reactors is less than 20% in 0-20 years age group and their mean size is also less than 20 mm. Operationally, it is a simpler method next only to No.4 above. Further investigations are considered necessary for final selection of this or any of the other methods.

Liquid BCG vaccine produced upto 1955 at the BCG Laboratory, Guindy, Madras induced low and variable levels of post-vaccination allergy. However, subsequent to improvement in production, its potency was adjudged as equivalent to Danish BCG vaccine. Later on, lower levels of post-vaccination allergy in Mass BCG vaccination campaign and in research studies were observed. A study was planned to compare the Madras BCG vaccine with Danish vaccine in terms of the potency of the strains, production efficiency of the laboratory and stability on storage. This was done by comparing the allergising capacity and size of vaccination lesions. On a predetermined date in each of four consecutive months, both laboratories supplied to the Research Team one week of fresh vaccines from their respective BCG strains and also fresh vaccine of strains borrowed from the other laboratory. With these six vaccines every month, in two consecutive weeks randomly, vaccinations were given to 2,978 tuberculin non-reactors. post-vaccination allergy was elicited 10 weeks later when size of BCG lesion was also noted. Viable counts on all vaccines were done by Madras Laboratory.

Though the Indian and Danish BCG vaccines induced similar levels of allergy, on further analysis it was found that Madras BCG strain was inferior to the Danish strain and that Madras Laboratory produced better vaccine than Copenhagen Laboratory. The vaccine produced from Copenhagen strain in Madras Laboratory induced the highest level of allergy. The stability of vaccines produced from Madras strain was found to be unsatisfactory. Results according to vaccination lesion size and their correlation with tuberculin reaction more or less confirmed the above findings. They were however not corroborated in terms of viable counts. Considering that the inferior quality of Madras BCG strain was due to mutation over time, seed lots of suitable BCG strain would ensure uniformly potent vaccine from Madras Laboratory.

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.

The Freeze-Dried BCG vaccine manufactured in India is sealed under vacuum. This though adds to its stability involves expensive production procedures. Sealing in presence of nitrogen is both simpler and economical. Before producing this vaccine for use on a large scale, it was considered necessary, to study the influence of storage at higher temperatures on the allergy inducing capacity on the basis of the size of local lesion and viable counts of Freeze-Dried BCG vaccine sealed either in vacuum or in the presence of nitrogen. For this, half of the ampoules of a batch of vaccine prepared in Madras BCG Vaccine Laboratory were sealed in vacuum and the other in presence of nitrogen. Randomly selected ampoules of both types of vaccine were exposed to 37o and 44o for 2, 6, and 18 weeks and another set at 4oC for 18 weeks. Two batches of liquid BCG vaccine were made as controls: 16 types of ampoules thus obtained were randomly repeated 5 times according to Standard Lattice Design. About 3000 school children without BCG scar, aged 5-14 years In Bundi and Kota districts of Rajasthan were vaccinated as per the study design. post-vaccination allergy with 5 TU RT 22 by measuring the size of vaccination lesions was recorded 3 months later. Viable counts on samples of ampoules from Freeze-Dried BCG vaccines exposed differently were done in the production laboratory after 18 weeks of storage.

The vaccine in 16 types of ampoules was significantly different. Liquid BCG vaccine resulted in higher level of allergy and larger vaccination lesions than Freeze-Dried BCG vaccine sealed under either method. The study has shown that Freeze-Dried BCG vaccine sealed under either method vacuum or nitrogen, gave satisfactory level of post-vaccination allergy and induration size of vaccination lesions, provided the vaccine was preserved at 4oC. Storage at 37o for more than 2 weeks and even 2 weeks storage at 44oC affected both types of vaccine badly as shown by post-vaccination allergy and viable counts. However, decrease in viable count with time and temperature was more pronounced in vaccine sealed in presence of nitrogen. Hence, there is a need to provide cold chain facility for Freeze-Dried vaccine all throughout the period.

Laboratory diagnosis of pulmonary tuberculosis is based on the presence of tubercle bacilli in sputum by direct microscopy, culture and/or animal inoculation. Culture examination, followed by tests for identifying the bacilli, is recognized as the most accurate and reliable method. Its efficacy depends on the laboratory techniques employed and its use in different practical situations such as epidemiological surveys, active community Case-finding, organization of diagnostic services and evaluation of diagnosis and treatment in tuberculosis control programmes. But the practicability of culture method in developing countries must be studied. The present paper deals with a systematic study of data from four investigations designed to elucidate the influence of certain operational factors on the utility of the culture method.

STUDY I: is a longitudinal survey in a randomly selected population in 134 villages in the three sub-divisions of Bangalore district. The analysis is based on the material from the first round, when two samples of sputum, (spot and overnight) were collected at intervals of 24-48 hours from persons aged 5 years and above having abnormal x ray shadows. The specimens were collected in house to house visits, stored after collection in insulated box with ice container and transported to the main laboratory at the National Tuberculosis Institute (NTI). The interval between collection of specimens in the field and culture in the laboratory was 1-7 days. A smear was stained and examined first by fluorescence microscopy and then by Ziehl-Neelsen (ZN) method. Each specimen was cultured on two slopes of Lowenstein-Jensen medium. All positive cultures were submitted to further identification tests; i.e., growth at room temperature, rate of growth at 37%C, pigment production in the dark and exposure to light, catalase and peroxidase reactions, niacin production, and sensitivity to INH, SM and PAS. STUDY II: relates to a mass Case-finding programme in Tumkur district when two specimens (spot and overnight) were collected from individuals aged 20 years and above with symptoms suggestive of pulmonary tuberculosis and from positive tuberculin reactors below 20 years voluntarily reporting with symptoms. The specimens were then treated in the same way as in Study I. STUDY III: pertains to the technical assessment of microscopy using Ziehl-Neelsen method performed by the auxiliary health staff of Peripheral Health Institutions in Bangalore district. A spot specimen was collected daily by auxiliary staff at each health facility from patients who were symptomatics. All smears were examined by ZN method at each centre and the corresponding sputum specimens were transported to NTI laboratory twice weekly. Duplicate smears were made and reexamined and culture was also done at NTI. All positive cultures were identified as in Study I. No refrigeration facilities were available in these centres and specimens were not transported in an insulated box. Rest of the procedures were followed as in previous studies. STUDY IV: is connected with operational and technical assessment of the District Tuberculosis Programme in Anantapur district one year after its commencement. A sample was taken from all patients who started treatment during a particular period but did not collect their drugs. Spot specimens were collected in the field, stored without any refrigeration and transported to NTI laboratory, thereafter the same procedure was followed as above.

An analysis of these four studies brought out certain operational factors affecting the culture method. (1) The results showed that an interval of 7 days between collection of sputum in the field and its processing in the laboratory did not affect the yield of positive cultures, even though the specimens were stored and transported under field conditions. (2) A higher proportion of positive cases were detected by culture than by direct microscopy but the magnitude of additional yield was dependant upon the procedure of selecting persons for sputum examination. (3) In service programmes restricted to persons with symptoms who attend diagnostic centres, the increase in yield is too small, to justify the introduction of culture examination.

This report is based on the study of 735 cultures of tubercle bacilli identified as human type. Sputum specimens were collected from patients attending the Lady Willingdon Tuberculosis Demonstration and Training Centre (LWTDTC), Bangalore, and from the mass Case-finding studies in semi-urban areas. Drug sensitivity tests for streptomycin, isoniazid, PAS and thioacetazone with different drug concentrations, different size of inoculum and for various length of incubation were carried out.

No difference was observed in the duration of growth between sensitive and resitant cultures in their first appearance on primary diagnostic cultures or sub-cultures on drug free slopes when innoculated with standard suspension. The primary cultures took about 3 weeks and sub-cultures 2 weeks to grow on drug free media. Large sensitive bacillary population required higher concentration of thioacetazone to inhibit the growth, suggesting standardization of inoculum size for sensitivity tests. Prolonged incubation period on drug slopes showed profound influence on the level of drug inhibiting concentration of thioacetazone; with the increase in incubation period, fall in growth of sensitive culture was not observed even on high drug concentration. The reproducibility of this observation on duplicate specimens from the same patients after shorter intervals excluded the possibility of experimental error. A reduction in the inhibition of growth of sensitive organisms on drug media with time is presumed to be due to either deterioration of the drugs in the media or due to adaptation by the micro-organisms. Because of the decrease in inhibition of growth, even sensitive organisms may be classified as resistant if reading of culture for drug sensitivity is prolonged beyond 3 weeks of the inoculation period. It is suggested that a standard inoculum size and a maximum limit of 3 weeks incubation period should be adopted for finding out sensitivity to thioacetazone. Cultures classified as sensitive to the three first line drugs or resistant to one or more, showed no difference in the pattern of sensitivity to thioacetazone.

The difficulty in staining tubercle bacilli is believed to be related to the complex surface structure containing a large amount of unsaponifiable wax. Any staining technique which can counteract the influence of this wax could therefore be expected to give better results. The standard method in vogue is the application of heat which renders the bacilli permeable to aqueous dyes. Several attempts have been made to develop a cold staining method for tubercle bacilli as for other organisms. Since this wax is soluble in chloroform, a cold staining method using carbol fuchsin containing chloroform was developed and the results of staining by this new method have been compared with the conventional Ziehl-Neelsen (ZN) method in the present study. Triplicate smears were made from 186 specimens and these were stained by ZN, Cold Staining (CS) and Fluorescent Microscopy (FM) methods. In addition, single smears of 343 specimens previously examined by FM were randomly divided into two subgroups and restained by ZN and CS methods respectively.

The results of examination of duplicate smears by ZN and CS methods showed a high degree of correlation with 75%(140/186) showing identical grading and only 8 were positive by one and negative by the other method. Of the 8 smears positive by CS alone, 7 were confirmed by culture, whereas 3 were positive by culture out of the 8 positive by ZN method. This indicates that those positive by CS alone are likely to be real cases, whereas those positive by ZN alone may include some false positive cases. As far as false negatives are concerned, there was no difference between ZN and CS methods. The reliability of these methods was judged on the basis of culture results and agreement among themselves. The cold staining method was found to be as efficient as ZN method in detecting different gradings of culture positives. In addition, preparation of stain, training of personnel for CS was also found to be as simple as ZN method.

The findings of two studies, (i) one on comparison of Ziehl-Neelsen method of staining of acid fast bacilli with and without alcohol decolourisation and use of Gabbet's Methylene blue (in place of decolourisation and counter staining) and (ii) comparison of two different types of Basic Fuchsin dye used in the preparation of Carbol Fuchsin, have been presented. The first study has shown that omission of alcohol decolourisation or the use of Gabbet's Methylene Blue has not influenced the detection of positives, though the latter has more often produced a non- satisfactory background. The second study has brought out the fact that two types of Basic Fuchsin are similar in every respect. However, the findings does not rule out the possibility of a bad dye giving rise to poor results. Need for conducting studies for simplifying the staining procedure has been stressed.

Assessment of a programme is the measurement of the extent to which its objectives have been fulfilled. This may be called assessment of efficacy. For this the objectives have to be defined in quantifiable terms i.e., the extent and period of time problem of tuberculosis will be reduced. This is yet to be done for the National Tuberculosis Programme (NTP). Assessment, of efficacy is difficult as the impact of Tuberculosis Programme is felt only after a fairly long period of time during which other socio-economic factors etc., also influence the problem. Any early assessment of problem reduction will only be a very costly attempt at proving the obvious and will possibly lead to frustration. Hence, a different methodology of assessment has to be adopted.

Assessment of Efficiency: Measurement of the extent to which the expectations for various activities under the programme are being fulfilled is referred to as assessment of efficiency. This seems to be a practicable solution to the problem of assessment of NTP. Realistic expectations for output and coverages under different activities can be set up on the basis of potentials on one hand and performance of programmes with reasonable efficiency on the other. Achievements of the programme could then be matched against these expectations. There is a need to define stages of programmes as different districts will have the programmes developed to different levels. Any overall assessment of such a heterogeneous programme situation may give a confusing picture. Advantages of this method are; i) number of districts which qualify to do from one stage to other will itself indicate the progress achieved; ii) after assessment attention can be concentrated on the corrective actions required. A detailed stage by stage assessment could be supplemented by monitoring i.e., a continuous watch on some key indices of the programme calculated from the periodic reports. This requires reasonably efficient reporting machinery. The key indices are: i) achievement of activities: Case-finding, treatment completion and BCG vaccinations against the expectations; ii) contribution from Peripheral Health Institutions; iii) No. of cases diagnosed against the prevalence of cases in the district.

Assessment should be objective enough to inspire confidence and its findings should be accepted or at least appreciated by the persons in-charge of the actual functioning of the programmes. For this, a proper climate for assessment should be created so that assessment is welcomed by programme organisers and corrective actions are taken soon after completion of assessment.

The present definition of the objectives of the National Tuberculosis Programme is too vague. A proper definition of the objectives, both longterm and intermediate, is needed. It should clearly state the index to be used for measurement of the problem and the expected values of this index at specific points of time. Another serious problem in assessment is to find out how much of the observed problem reduction is due to the impact of the programme and how much due to (or in spite of) the natural trend (downward or upward). Repeated surveys cannot provide this information and keeping of control groups is not feasible. Epidemetric models help in choosing the index for measuring the problem and fixing intermediate and long term objectives in terms of this index. They also help to take the natural trend into account, while assessing the programme.

Prevalence of infection is the least sensitive index. Prevalence of disease and incidence of infection may lead to over optimism. Incidence of disease is most suitable but difficult to get in developing countries. Hence, prevalence of infection or disease has to be chosen. Difficulties of the former are interference by BCG vaccination and non- specific sensitivity. The use of BCG induration to estimate prevalence of infection has some advantages and it is worthwhile to investigate further this possibility. Using epidemetric models, two methods of assessment of effectiveness are suggested. One to carry out prevalence surveys but need not be attempted unless programme efficiency has been quite high for at least 10 years. The other is the assessment of efficiency of the programme which can be easily carried out.

BCG vaccination (prevention) and Case-finding followed by treatment (cure) are two universally accepted methods for controlling tuberculosis. BCG trials in selected populations have provided some information on the protective value of BCG, generally over short periods of time (below 20 years) and mainly among younger populations. Efficacy of different drug regimens for treatment of tuberculosis are well established and a number of studies on the effectiveness of different types of treatment programmes on the patient population are available. However, the manner in which BCG and treatment affect the four epidemiological indices of prevalence & incidence of infection and prevalence & incidence of disease in the community, over a period of time, has not been reported in detail.

This paper describes a simple set of models which can be used to predict the trend from these indices under different types of TB programmes (including no programme) which can be depicted as a combination of 5 programme parameters. How these models can be used for planning and assessment of programmes have been demonstrated by some examples. The trend in the incidence of disease obtained from this model is similar to that reported by Waaler et al in 1974. Unlike earlier models, the present model starts with cases and the calculations involved are simple enough to be handled by calculators and computer facilities are not necessary.

The Health Care Delivery System (HCDS) consists of the governmental (public) and non-governmental (private) health agencies and the facilities they provide for one or more of the three main aspects of comprehensive health care viz., curative, preventive and promotive. The delivery of comprehensive health care in a country like India poses many problems. An adequate network of organisation, particularly governmental, has to be built up. This has to be primarily directed towards delivery of health care in the rural areas with considerable emphasis on preventive and promotive health. Such an organisational set up has to be manned by a large army of personnel with varying types and levels of basic professional education. At present both the know how for practical application of professional knowledge under varying conditions and proper attitude for the same are often inadequate among the health personnel. These can be improved and maintained only on the basis of a long term plan for job training. Permanent facilities should be available so that training of new recruits and staff on promotion/transfer can be taken care of regularly and systematically. Also, refresher courses have to be undertaken regularly to keep the staff abreast of the developments in delivery of health care. At present juncture, Multi Purpose Worker (MPW), community level workers and health assistants in the public sector of HCDS, also require the training.

To make such training more purposeful, it must be emphasised that planning for training has to come well ahead so that implementation of any programme is not unduly delayed due to absence or shortage of properly trained health workers. To illustrate this, the training requirements of the National Tuberculosis Programme (NTP) which is integrated with general health services have been dealt below: Governmental Agency: i)Programme workers who attend patients and community should be trained by the District TB Centre (DTC) key personnel as in service training or on the job training, ii)Programme supporter PHC doctors in addition to being programme workers, DHO, ADHO, ADHS (TB) etc should undergo orientation course for 8 to 9 working days. iii)Trainer Professors and lecturers of preventive & social medicine, tuberculosis and medicine of medical colleges, trainers of central training institute also undergo orientation course for 8-9 days. iv)Research Worker in research methodology for 4 weeks. v)Programme planners & Decision Makers a)Ministers of Health, Secretaries & Directors of Health both at state and central-levels By periodic meetings, personal discussions, participation in Central Council of Health meetings. b)TB Adviser, TB-Officer By periodic meetings, written communication, attending seminars. Similar estimates have to be made for other components of HCDS. Taking all these into consideration, the number of training institutions/facilities which are required to meet all the training needs can be worked out, keeping in view their proper regional or geographic distribution. The next step would be to organise the education and training of private health workers and health consumers. Adequate information for the detailed planning is not available for these two categories. But, a beginning has to be made as quickly as possible.