Saturday 9 February 2008

Early Detection of Tuberculosis

Yes, it is a hidden disease. The patient remains asymptomatic for long periods, and the disease is often diagnosed during routine tests, when a chest X-ray reveals the 'hidden' disease, i.e. tuberculosis. It has thus an occult/hidden character.

In places where the incidence of tuberculosis is not marked, 'tuberculin test surveys' be carried out among the general population, which gives an idea of the number of cases who are tuberculin positive, i.e. infected with tubercle bacilli (although the disease may be inactive in the majority of them). Those who have shown positive in the tuberculin test should be subjected to an X-ray examination of the chest, so as to find out hidden/ symptomless, especially active cases of the disease - in other words those who are suffering from active tuberculosis, but still showing no symptoms of the disease, can be detected.

For an epidemiological survey, small X-rays may be taken through a special X-;ray plant fitted in a van, which moves from place to place or village to village, or visits poor communities/slums. X-rays are taken in quick succession, one by one, of the various persons, who 'are made to stand in a queue before entering the van. They come out of the van after the exposure for the chest X-ray. This is called miniature mass radiography (MMR). These surveys were most common in the past when the disease was at its peak.

However, in places where the incidence of tuberculosis is high, all persons in such areas are expected to be infected with tubercle bacilli, i.e. they will be found as tuberculin positive. Hence the tuberculin test is of little value at such places, for epidemiological survey, and therefore, one can directly switch on to MMR study, for the detection of both hidden and active cases of tuberculosis.

It may, however, be noted that X-ray of the chest alone may not be always confirmatory of the diagnosis/activity of tuberculosis, either in a mass surveyor in an individual. Hence, when the disease is suspected, other tests, must be carried out, including a detailed clinical examination,'keeping the symptomatology of the patient in view.

Also, in the MMR study, small X-ray films taken may not give the true picture of the disease. And, there even may be variations in reading these X-ray films. Even if a tubercular lesion appears to be positive, it must be confirmed by a large chest X-ray, as well as by other tests. It is never wise to administer treatment of tuberculosis to a patient only on the basis of miniature radiographs.

The MMR study is now no longer widely carried out in places/ countries where the incidence of tuberculosis is low, because too few cases may be found positive, involving the expense of a lot of time, money, and above all, at the risk of exposure to X-ray radiation for a large population.

Also, in all those groups of persons who daily come in contact with a large number of people, such as the bus-drivers, conductors, teachers, and the entire medical staff, like doctors, nurses, attendants, technicians, radiographers etc., chest X-rays should be carried out because they comprise the high-risk groups. Spread of the disease has also been noticed in creches, schools, school-buses, hostels, and even in nursing homes, etc.

Similarly, the disease must be detected in servants, waiters in restaurants, salesmen, postmen, washermen, sweepers, barbers, cobblers, etc. People living in slums and shanty towns, chawls, etc. should also be checked for the detection of tuberculosis.

All efforts must be made to unearth 'hidden' cases of tuberculosis, as they are most dangerous to society. They go on spreading the disease for a pretty long time, till it is diagnosed and treated.

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