The paper has illustrated the use of mathematical model (epidemetric model) for the prediction of the trend of tuberculosis in a given situation with or without the influence of specific tuberculosis control programme. The paper also advocates the use of models for evolving applicable control measures by reflecting their interference in the natural trend of tuberculosis in control areas. These models were constructed by applying methods which have been developed and utilised in other social sciences.
The precise estimates of the various parameters entering the model must be available if realistic long term results are to be achieved through model methodology. The need for exact data regarding prevalence and incidence of infection and disease, necessitates longitudinal surveys in large random population groups. It is, however, the present authors firm opinion that it would be fruitful for almost any health department, to compare their best available epidemiological knowledge in a system of relationships in order to quantify their concept of the situation. Such an exercise in mathematics would, in any case, serve to sharpen the epidemiologists thinking and would lead them to appreciate what data they need most urgently. The model may help in predicting the trend of tuberculosis in a given situation.

The National Sample Survey demonstrated that tuberculosis is one of India's major public health problems, disease being equally prevalent in both rural and urban areas. To bring about the reduction of the tuberculosis problem in a limited time the programmes developed at National Tuberculosis Institute (NTI) must have the following characteristics: i) they must be firmly rooted in the general health services and contribute to their development. ii) they must be applicable to the large majority of the districts of India. The existing clinical knowledge of tuberculosis should be brought to the realm of public health application, for which NTI must accumulate a body of knowledge on the efficiency of various control programmes under field conditions and their operational feasibility.

Operations Research at NTI consists of following elements (i) Data collection on (a) epidemiological factors by conducting base line and longitudinal surveys (b) operational factors by comparing Mass Campaign approaches and Community Development Approaches (c) Sociological and economic factors by studying the awareness of symptoms among TB patients, economic consequences of TB and acceptability of long term drug treatment (ii) construction of various epidemetric and operational models to give information on the efficacy of various tuberculosis programmes (iii) test run at the moment NTI is operating a District TB Programme (DTP) in Anantapur and a city programme in Bangalore. These programmes have been formulated to a large extent on the basis of preliminary data not organised in model form. Some provisional conclusions are beginning to emerge from the various elements of the Operations Research Programme operating for a year. The general health services are proving to be capable of playing their essential role in the diagnosis and treatment of tuberculosis, provided they are assisted, at district level, by a special tuberculosis service for planning, partial supervision, evaluation and referral. With existing chemotherapy the treatment organisation is the most crucial part of the tuberculosis services, and the decisive role is played by the field organization engaged in preventing and curing treatment default. The most critical requirement of any control programme is an ample provision of drugs, to be supplied free of cost to the patients. Over half the X-ray active cases (including more than three quarters of the sputum positive cases) are aware of symptoms of the disease, and Case-finding can therefore, for some time to come, be based on the self advertising attraction of a free treatment service within a walking distance, associated with a simple sputum diagnosis at Primary Health Centre level and referral X-ray diagnosis at taluk or district level. NTI's task is formidable, its resources limited. We believe that through its Operations Research Approach, NTI utilises most effectively its limited facilities towards the solution of India's tuberculosis problem.

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.

This study was undertaken in 34 villages and 4 town blocks where a few weeks earlier an epidemiological survey was carried out. All persons above 20 years whose photofluorograms were read as inactive, probably active, or active by at least one reader, were age sex matched with an equal number of X-ray normals, to form the experimental and control groups respectively. Thus, a total of 2,106 were eligible for social investigation. Interview sheets, with particulars of the name and location of village, household number, and individual number and the identifiable data of the interviewees were made available to the social investigators at random for contacting and interviewing them at their homes. The interviews were non- suggestive in nature and deep probing on the details of symptoms experienced by the respondent, which were fully recorded. About 79% of the experimental group and 83% of the control group were satisfactorily interviewed, which constituted the data further analysed. Of the numerous symptoms recorded, only that were associated with pulmonary tuberculosis were considered, of which cough occurring for one month or more, fever for a month or more, pain in the chest, haemoptysis and all combination of these four symptoms were analysed statistically.

Cough was found to be the most important single symptom. It was not only the most frequent symptom alone or in combination in the experimental group but was less frequent in the control group that 69% of sputum positive and 46% of radiological positive had cough while only 9% of the control group had it. Considerably fewer people had fever and pain in the chest. Pain in the chest appears to be non- specific, giving a ratio of only 2:l among the experimental and control groups while fever was in the ratio of 6:l and haemoptysis was ll:l. It was seen that 69% of the sputum positive cases, 52% of the X-ray active or probably active, 29% of the inactive and 15% of the normals (control group) had at least one of the above mentioned symptoms. In all the groups, the proportion of symptoms were higher among males than among females. In both males and females the prevalence of symptoms was higher in the middle age groups than among the younger or older groups. This age variation was more marked in the females. The findings of the study were analysed further along with the data obtained from a couple of minor investigations, conducted in the rest of the 28 villages which formed the total of the villages surveyed epidemiologically. This brought out further that 95% of bacteriologically positive cases are aware of symptoms, 72% experience 'worry awareness' and 52% form the action taking group. The above findings have been of considerable importance in planning further studies and in formulating the National Tuberculosis Programme.

Tuberculosis control by mass domiciliary chemotherapy is now being attempted on an increasingly large scale in the technically underdeveloped countries. The National TB Institute (NTI), Bangalore is an important centre for the development of such programmes and a study reported in this paper is an enquiry into the working of an urban tuberculosis programme which is operated under the auspices of the Institute. The excellent results of controlled clinical trials have lead to widespread belief that tuberculosis problem can be reduced significantly and rapidly by use of mass chemotherapy. However, the findings of such programmes elsewhere showed that by a long term continuous effort year after year, the removal of infectious cases can bring about a gradual reduction of the problem. Hence, it was necessary to study the treatment organisation of domiciliary chemotherapy on a large scale in respect of patients’ behaviour towards the programme during the treatment period. Three types of problems encountered in an urban tuberculosis programme are dealt in this paper: (1) problems related to the patients who are under treatment at the Lady Willingdon TB Demonstration & Training Centre (LWTDTC); (2) patients who prefer to take treatment from other institutions and (3) patients who come from outside the city. Study population consisted of 784 radiologically positive patients diagnosed at the LWTDTC from March 61 to May 61. All the outpatients were submitted to a tuberculin test and examination by a 70 mm photofluorogram. Those who were X-ray positive were given bacteriological examination of a spot sample of sputum by both smear and culture on their second visit scheduled on the third day. Of the 784 persons 318 (54%) were found to excrete tubercle bacilli. All patients suffering from active tuberculosis and sputum positive disease were put on a treatment regimen of 300 mg of isoniazid per day for a period of one year. During the course of the study a few of the sputum positive cases were given 10 gms of PAS in addition. The study population was interviewed by the Social Investigators of NTI: initially at the clinic immediately after their diagnosis, defaulters at their homes within four weeks of their defaulting and all patients after twelve months of treatment period. The coverage was 100%, 65% and 76% respectively.

The major problems identified and quantified were: Of the 784 patients under study, 84 (11%) did not even return to learn the results, 46 (6%) patients houses could not be traced, 138 (17%) resided outside the city, 48 (6%) emigrated during the treatment, 173 (22%) took treatment from outside sources, 156 (20%) took treatment regularly from the clinic and 139 (18%) also took treatment in the clinic but irregularly. Various reasons were given for defaults in drug collection, a sizable proportion of which could have been avoided through better organisation and administrative procedures and good initial motivation at the clinic. Default is a complex behaviour pattern and this study did not bring out any correlation between default and the economic, social, educational or other status of the patient. With changes in the system leading to a good treatment organization, it should be possible to have a higher percentage of regular patients than 20% as at present. About 64% sputum conversion among regular patients and estimated 25% among defaulters was observed.

The research which is foremostly needed in the poor countries of the world is not inventive and experimental research; the demand of these societies is no longer for new techniques and new inventions to improve their human material. Their demand is for systems composed of largely known techniques which could improve the human material to a level they can now afford and give the optimal utilisation of scarce economic resources. Research that satisfies this demand can be called application research or operations research. The term Operations Research has been borrowed from certain other fields i.e., military and industry. The techniques have mainly been developed during the second world war military field operations and later on applied in the field of industrial management. The spectacular progress of public health in the developed countries during the last century was a result of interaction mainly between economic progress and the development of science and not as a result of application of operations research. Over a period of time a very large number of inventions and experiences in techniques are available to apply in logical systems. This relative preponderance of technical knowledge over economic capacity is the social fact and many developing countries cannot choose the best and have to depend upon the utilisation of operations research in public health.

The following are the major seven phases in Operations Research applied to Public Health Services: i) formulation of the problem, ii) collection of data, iii) analysis and hypothesis formulation, iv) deriving solutions from the model, v) choosing the optimal solution and forecasting results, vi) the test run and the control system, vii) Recommending implementation. Operations Research can be a continuous process or even one time effort. For a country like India it could be a permanent feature of the national health services. The minimum composition of the Operations Research team is probably a public health administrator, an epidemiologist, a mathematician, a statistical and social scientist.

The essence of Operations Research is that logical thought combined with careful observation and methodological analysis, which should form the basis of decision making. Operations Research thus may be called as the science of common sense.