Raj Narain, SS Nair, G Ramanatha Rao & P Chandrasekhar: Bull WHO 1966, 34, 639-54 & Indian J TB 1966, 13, 129-46.

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.


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%).


Radha Narayan & N Srikantaramu: NTI Newsletter 1987, 23, 76-90.

This study based on an individualistic model examines the significance of factors such as symptom awareness, knowledge about the disease, recall of clinic instructions, economic problems and social interaction in the treatment regularity of patients with pulmonary tuberculosis through a multi dimensional comparison of regular patients, irregular patients and their households. There was no difference in the symptom awareness of the two groups of patients. Thus frequency of medical visits is to adopt the sick role than of stress. In NTP patients are denied the sick role has “rest” and “special diet” the vital elements of traditional treatment are not recommended as part of treatment. Yet, three of the four cardinal symptoms of pulmonary tuberculosis, cough fever and haemoptysis being of a nature observable by others, have been observed by the households to the extent similar to patients awareness. Most of the patients who take treatment from non- paying centres such as the LWTDTC live in overcrowded areas where there is generally a high degree of neighbourhood interaction not only social but in sharing common utilities such as courtyard, water tap, bath room, toilet etc. It is therefore not surprising that nearly half of the patients and households said that the neighbours knew about the patient's illness.

Seeking multiple sources of treatment is a common behaviour pattern of patients. Yet, it is disconcerting to find that tuberculosis patients who can ill afford to pay and who need to be under treatment for a long period should 'shop around' for treatment. It is the irregular patients who have sought treatment at other agencies more often. The study shows that patients showing regular drug collection have had help from household members in collecting the drugs. They have also had help from household members in remembering to consume the drugs. More of the households of the regulars mentioned LWTDTC as the place of treatment while in the in case of the households of the irregulars mentioned several places of treatment.

No significant differences were seen between the regular and irregular patients in their social interactions within the households or in the behaviour of households towards the patients. To the household, economic difficulties were the most important, perhaps for the reason that the patients were men in the working age group. Though economic difficulties were important to patients also the predominant aspect was pain and discomfort the physical dimensions of suffering. A treatment agency that can pay adequate attention to the relief of physical suffering and non- relapse of symptoms can perhaps help to improve treatment regularity of tuberculosis patients appreciably.