National Tuberculosis Institute, Bangalore-3: NTI Newsletter 1990, 26, 25-27.

A methodology in brief about conducting Classical Tuberculosis Sample Survey and Tuberculosis Surveillance is given below:

A tuberculosis prevalence survey to measure the problem of tuberculosis in the community is a challenging assignment especially so when it is to be conducted by an organisation not created with the specific objectives of carrying out research work e.g., the District Tuberculosis Centre, State Tuberculosis Centre, etc. However, following procedure is described in brief: (1) Selection of district for the study, (2) Collection of basic data like size and distribution of population, number of towns and villages, (3) Selection of sample population for survey by valid statistical methods, (4) Census enumeration of study population by trained census takers - preparation of cards for all the individuals, (5) Tuberculin testing & reading of all subjects under study, (6) BCG scar survey, (7) X- ray examination of the eligible population (> 10 years or > 15 years). Interpretation of X-rays by standard readers, (8) Collection of sputum from chest symptomatics and X-ray abnormal individuals, (9) Transportation of sputum to central laboratory (necessary precaution to be taken during storing and transportation), (10) Sputum to be examined by trained staff, (11) Compilation, analysis and interpretation of data. Number of working teams with full complement of staff depends upon the size of the study population and the time frame of the study. An average survey team may have the following personnel on its strength: Medical Officer - One, Census Takers - Three, Tuberculin Tester & Reader (one each) - Two, Lab Technician - One, Lab Asst. - One, X-ray Technician. - One, Dark room attender - One. Equipment required: Mobile X-ray unit - mounted on a jeep along with the generator mounted on another jeep, Laboratory infrastructure, Vehicles preferably jeep.

Apart from the above, the team may need part time assistance of a Statistician and a few Statistical Computers. In case a state is interested to carry out an epidemiological survey, it may need to create the above infrastructure. Once arranged, it may request the National TB Institute (NTI) to train the required staff on standard survey techniques under field situations which is very essential.

In contrast to the more complex methodology involved in a classical survey described above, an alternative, much simpler and indirect method to assess the problem of tuberculosis in the community is by finding out the infection rate, through tuberculin surveys. It may be possible to estimate the prevalence of sputum smear positive disease from infection rate. Such survey is conducted by subjecting the age-specific unvaccinated population to tuberculin test periodically. For carrying out the work, one to two teams composed of three to four properly trained tuberculin testers and readers are needed along with at least two vehicles and a standby vehicle per team. Budgetary support for petrol, travelling and daily allowance of staff, and for minor miscellaneous expenditure like stationery, spirit, etc., may be required to be provided. Training could be imparted to such personnel at NTI and their services utilised exclusively for carrying out tuberculin surveys as a regular ongoing surveillance activity. If this methodology is found suitable, one may take action to create posts of tuberculin testers and readers in suitable scales and draft them for training in tuberculin survey methodology. The Institute will be happy to train the required personnel for the purpose, as well as analyse the data so collected for use by the states.