EPIDEMIOLOGY <<Back
 
 
002
SIZE & EXTENT OF TB PROBLEM IN URBAN & RURAL INDIA
Raj Narain: Indian J TB 1962, 9, 147-50 & also in Proceed Natl TB & Chest Dis Workers Conf 1962, 155-68.

The aim of modern Public Health Programmes, is a reduction in the total amount of disease in the community. The unit for treatment and cure is not an individual but a sick community. With this new aim, it becomes essential to know the size and extent of tuberculosis in the community as it will be helpful not for purposes of planning only but essentially for the assessment of their effect on the problem. An attempt is made to review the important features of the available knowledge about infection, morbidity and mortality through various surveys. (i) Prevalence of Infection: Tuberculosis infection is widespread in both urban and rural areas of almost all parts of the country. Nearly 40% of the population are infected. To avoid the effect of non- specific allergy and get a more reliable demarcation, tuberculin reactions of 14mm and more were considered as positive by National Tuberculosis Institute. (ii) Prevalence of morbidity: The prevalence of radiologically active tuberculosis in the population is likely to be 1.5%, Prevalence of bacteriologically confirmed diseases is 0.4%. Based on single sample of sputum examination, the prevalence of infectious cases in the country is probably an under estimate. About two million are infectious at any one point of time. (iii) Mortality: Deaths from tuberculosis in the country is not definitely known. The impression of clinicians that death due to tuberculosis have fallen sharply may not be true. Half a million deaths will appear an underestimate. About 250 per 1,00,000 persons i.e., one million deaths due to tuberculosis per year seems to be a reasonable estimate. (iv) Bovine Tuberculosis: Only a few cases in man caused by the bovine tubercle bacillus have been reported although 2.75% to 25% of cattle have been found tuberculin reactors.

To put in a nut shell, the problem of tuberculosis in India is a gigantic one and our means of fighting it with the single tool of BCG, do not even touch the fringe of the problem.

KEY WORDS: INFECTION, SUSPECT CASE, CASE, MORTALITY, COMMUNITY.

011
FATE OF CASES DIAGNOSED IN A SURVEY
Raj Narain, G Ramanatha Rao, G Chandrasekhar & Pyare Lal: Proceed Natl TB & Chest Dis Workers’ Conf, Calcutta, 1966,72-78.

The report describes the changes that occurred during second survey carried out after an interval of one and half years in the cases diagnosed at the first survey done during 1961-62 from among a total population of about 62,000 in 119 villages in Bangalore District. It was observed that (1) Of the 62 sputum smear positive cases also having suggestive chest X-ray shadows, 34% had died, 35% were sputum positive and 31% had become culture negative after 1½ years. Of the 10 smear positive cases who were X-ray normal, non-e was culture positive at the start and 7 were negative by culture and smear after 1½ years. Of the 67 scanty smear positive cases (1 to 3 bacilli seen), only 3 were sputum positive, 10 were having X-ray shadows and half were tuberculin negative after 1½ years. (2) Of the 88 culture only positive cases (20 or more colonies and with X-ray evidence of disease) 31% had died and 47% continued to be sputum positive after 1½ years. A much smaller proportion of these changes occurred among culture positive cases with less than 20 colonies. (3) There were 457 persons having radiologically active tuberculosis on the basis of interpretation of a single X-ray picture by two independent readers but whose sputum were negative for AFB (suspect cases). Of these, 38% were tuberculin negative also. Of those suspect cases who were tuberculin positive, 9% become sputum positive after 1½ years, while only 2% of the tuberculin negative suspect cases became sputum positive.

It is concluded that there is a lot of variation in fate among the different categories of cases of pulmonary tuberculosis. Further, attention has been drawn to the possibility of self healing in about 30% of the bacillary cases after 1½ years.

KEY WORDS: FATE, CASE, SUSPECT CASE, NATURAL CURE, PREVALENCE.

017
DISTRIBUTION OF TUBERCULOUS INFECTION AND DISEASE IN CLUSTERS OF RURAL HOUSEHOLDS
SS Nair, G Ramanatha Rao & P Chandrasekhar: Indian J TB 1971, 18, 3-9.

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%).

KEYWORDS: RURAL, HOUSEHOLDS, CLUSTERS, CASE, SUSPECT CASE, CONTACT, PREVALENCE, INFECTION, DISEASE, SURVEY.

019
SOME ASPECTS OF CHANGES IN RURAL POPULATION AND FATE OF TB CASES AFTER AN INTERVAL OF TWELVE YEARS
MS Krishnamurthy, KR Rangaswamy, AN Shashidhara & GC Banerjee: NTI Newsletter, 1974, 11, 1-7.

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.

KEYWORDS: FATE, CASE, SUSPECT CASE, MORTALITY, MIGRATION, RURAL POPULATION, DEMOGRAPHIC CHANGES, SURVEY.

020
SIGNIFICANCE OF PATIENTS WITH X-RAY EVIDENCE OF ACTIVE TUBERCULOSIS NOT BACTERIOLOGICALLY CONFIRMED
SS Nair: Indian J TB, 1974, 21, 3-5.

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.

KEY WORDS: CHEST SYMPTOMATICS, RURAL COIMMUNITY, SUSPECT CASE.

021
INTERPRETATION OF PHOTOFLUOROGRAMS OF ACTIVE PULMONARY TB PATIENTS FOUND IN EPIDEMIOLOGICAL SURVEY AND THEIR FIVE YEAR FATE
GD Gothi, AK Chakraborty & GC Banerjee: Indian J TB 1974, 21, 90-97.

In this study the material from “Five year study of Epidemiology of Tuberculosis” (1961-68) has been analysed to find out an improved method of interpretation of chest X-rays to get accurate estimation of prevalence of “suspects” in the community. The population of a random sample of 119 villages from the three taluks of Bangalore district was surveyed four times with intervals of 1½ to 2 years by tuberculin testing, 70mm chest photofluorography and sputum bacteriology. Out of 45,434 persons X-rayed during the first survey, 590 were read as active pulmonary tuberculosis on the basis of single picture interpretation by two independent readers. Of them, 460 being sputum culture negative were classified as initial “suspects” and these were reviewed in this study by the panel of three readers together by the method of “joint reading”. The interpretation was done comparing the serial X-rays of individuals taken at intervals along with other available examination results and personal data. Out of 460 initial suspects only 110 (23.9%) were confirmed as “suspects”, the remaining were judged as non-tuberculous and/or inactive tuberculous (62.2%) and normals (13.9%).

Fates on five year follow up were compared between 85 “confirmed suspects” and 385 “initial suspects”. The mortality and sputum positive status were found more among the former group i.e., 23.5 and 25.5 and 14% and 7.2% respectively. Radiologically, 48.7% of the confirmed suspects and only 10% of the initial suspects could be classified as suspects at 5th year follow up. Incidence of bacillary disease among the confirmed suspects was also found higher. On the basis of “joint reading” and five year follow up study, the limitations of single picture interpretation resulting in considerable over diagnosis were clearly seen. The comparative reading of serial X-rays along with other examination results did help in the better assessment of etiology and activity status of disease. Of the X-rays read as non-tuberculous and inactive tuberculous when reviewed by “joint reading” method, about 67 more suspects could be added. Even then the estimates of prevalence of “suspects” based on single film interpretation which are widely used in India appear to be about 3 times the actual prevalence.

KEY WORDS: FATE, SUSPECT CASE, X-RAY, JOINT READING, SINGLE PICTURE, OVER DIAGNOSIS.

037
PREVALENCE AND INCIDENCE OF SPUTUM NEGATIVE ACTIVE PULMONARY TUBERCULOSIS AND FATE OF PULMONARY RADIOLOGICAL ABNORMALITIES FOUND IN A RURAL POPULATION
GD Gothi, AK Chakraborty, VV Krishnamurthy & GC Banerjee: Indian J TB 1978, 25, 122-31.

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%.

KEY WORDS: SUSPECT CASE, PREVALENCE, INCIDENCE, RURAL POPULATION, FATE.

048
PREVALENCE, INCIDENCE AND FATE OF SUSPECT CASES OF TUBERCULOSIS IN A RURAL POPULATION OF SOUTH INDIA
VV Krishna Murthy: NTI Newsletter 1982, 19, 75-80.

The data from a longitudinal survey conducted in Bangalore district from 1961-1968 by National Tuberculosis Institute was analysed to find out the prevalence, incidence and fate of suspect cases. In brief, the survey was conducted in 119 randomly selected villages in three taluks of Bangalore district and repeated within the next five years. At each survey, eligible population was subjected to tuberculin, X-ray & sputum smear and culture examinations.

The overall prevalence rate of suspect cases among persons aged five years and more was 1.06% at I survey, 0.68%, 0.49% and 0.43% at II, III and IV survey respectively. In males, the prevalence rate was 1.19% at I survey & 0.62% at IV survey corresponding figures for females were 0.94% and 0.24% respectively. A decline of prevalence of suspect cases from 1.06% at I survey to 0.43% at IV survey was observed. The overall incidence of suspect cases was 0.16% between I & II surveys, 0.10% between II & III, and 0.06% between III & IV surveys. The overall as well as age specific annual incidence rates between III & IV surveys were significantly less than that between I & II surveys. At all the three intervals the incidence increased with the age. Incidence of suspect cases in males was more than that in females. Change in disease status over a period of time is termed as "fate". The disease status was classified as (i) cure (ii) continued to be suspect case (iii) converted into bacillary cases and (iv) dead. The percentage of cure (51.9%, 53.2% and 50.3%) and conversion into bacillary cases(7.2%,5.8% and 5.4%) were almost the same at all the three intervals. But the percentage of those who remained suspect cases reduced from 33.5% at the end of 18 months to 17.5% at the end of 60 months. On the other hand, the death rate increased from 7.4% at the end of 18 months to 26.8% at the end of 60 months. The decreasing trend of continuing to be suspect cases at the rate of 10% between two observations, appears to be corresponding to the increasing trend in the death rate as seen from the observations made at the three intervals.

KEY WORDS: PREVALENCE, INCIDENCE, FATE, SUSPECT CASE, RURAL COMMUNITY, LONGITUDINAL SURVEY.
 

 
  OPERATIONS RESEARCH  
 
A : Problem Definition
 
076
A SOCIOLOGICAL STUDY OF THE AWARENESS OF SYMPTOMS SUGGESTIVE OF PULMO NARY TUBERCULOSIS
D Banerji & Stig Andersen: Bull WHO 1963, 29, 665-83

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.

KEY WORDS: SOCIAL AWARENESS, SYMPTOMS, SOCIAL ASPECTS, CASE, SUSPECT CASE.
 

  B : Programme Development  
 
098
CONTROLLED STUDY OF THE EFFECT OF SPECIFIC TREATMENT ON BACTERIOLOGICAL STATUS OF "SUSPECT CASES"
Aneja KS, Gothi GD and GE Rupert Samuel: Indian J TB 1979, 26, 50-61.

The effect of specific anti TB drugs on patients having smear negative radiologically positive pulmonary tuberculosis (suspect cases), was studied in Lady Willingdon Tuberculosis Demonstration & Training Centre (LWTDTC), Bangalore during 1975 & 1976. The main objective was to know the proportion of suspect cases treated under the programme requiring the specific treatment with anti TB drugs. A total of 457 suspect cases were randomly allocated to one of the two regimens; 228 patients were treated with INH + Thioacetazone (TH) and 229 with calcium gluconate (Placebo) regimens, for one year. The placebo group allowed a concurrent comparison of status of suspect cases without any specific treatment. After the intake, sputum examination by direct smear, culture for M.tuberculosis and sensitivity for drugs as well as X-ray examinations were carried out at 0, 2nd, 4th, 6th, 9th and 12th month of treatment.

Among the 228 patients on TH, 103 (45.2%) were real suspect cases, 83 (36.4%) sputum positive and remaining 42 non- tubercular. Similarly, out of the 229 patients on placebo regimen, 110 (48%) were real suspect cases, 61 (26.5%) sputum positive and 58 non- tubercular. The effect of treatment was measured by observing the incidence of bacteriologically positive or radiologically active disease from among the real suspect cases of the two groups. At the end of the treatment period, 12.6% of TH group and 29.7% of placebo group were broken down, the difference being statistically significant. Further, an element of self healing was also observed, as about 40% of patients in placebo group showed either clearance of lesions or continuing regression which could be due to self healing or the lesion being non- tubercular in nature. About 30% of the 457 patients at the start of the study were real cases of tuberculosis who under the programme were missed and 20% broke down with bacteriological positive or progress to radiologically active disease when treatment was not offered. Thus, nearly 50% of the suspect cases diagnosed in the programme required anti TB treatment and for those requiring treatment, perhaps TH is not sufficient, as 12.6% broke down in spite of treatment. It would be appropriate to treat suspect cases both from the clinical and epidemiological point of view after taking due precautions to remove non- tubercular cases by doing repeat sputum examination.

KEY WORDS: CONTROL STUDY, SUSPECT CASE, TH REGIMEN, EFFICACY.

100
INFLUENCE OF INITIAL MOTIVATION ON TREATMENT OF TUBERCULOSIS PATIENTS
KS Aneja, MA Seetha, Hardan Singh & V Leela: Indian J TB 1980, 27, 123-29.

The effect of initial motivation on pulmonary tuberculosis patients in terms of regularity of drug collection and pattern of default for three months was studied at Lady Willingdon Tuberculosis Demonstration & Training Centre (LWTDTC), by adopting three different schedules of motivation (i) motivation as per routine procedures of District Tuberculosis Programme (ii) issue of simple brief instructions only and (iii) motivation with reduced contents and with change in sequence of points. The patients without history of previous treatment were randomly allocated to these 3 groups. All the three groups were similar in respect of age and sex composition, sputum status, extent of disease, duration of symptoms, education level and the distance that the patient had to travel for collection of drugs. However, there were more housewives in Group II.

The findings of the investigations were: Of the 139 patients in Group I, 49.6%, of the 126 in Group II, 46.7% and of the 142 in Group III, 47.2%, had made all the three collections. On the whole different schedules of motivation did not significantly affect the behaviour of the patients in making all the three monthly collections. However, patients in Group II with simple instructions were more regular and made less number of defaults. There was also a suggestion that sputum negative patients required more than mere instructions. The best response in such cases was in Group III, wherein motivation was neither very elaborate nor very brief and in which sequence of points was so arranged that stress on important points was laid early enough to remain within the recalling memory of the patients.

KEY WORDS: CONTROL PROGRAMME, TREATMENT COMPLETION, INITIAL MOTIVATION, SUSPECT CASE, CASE.
 
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