BCG vaccination in India and tuberculosis in children: Newer facets

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Abstract
With the extended programme of immunisation and since 1985 the universal programme of immunisation and the coverage status of BCG vaccination in India has been very good, although it is still unsatisfactory in the eastern states. It is emphasized that BCG vaccination cannot prevent natural tuberculous infection of the lungs and its local complications, although it reduces the haematogenous complications of primary infection. However, this is not true for malnourished children who, inspite of BCG vaccination, develop serious, and often fatal types of tuberculosis such as miliary, meningitic and disseminated tuberculosis. The tuberculin anergy in malnourished children, is mainly responsible for high morbidity and mortality. BCG vaccinated, well-nourished children manifest modified patterns of tuberculous disease, following infection. The most important manifestation is the increased incidence of intrathoracic tuberculosis, specially enlargement of the various groups of mediastinal nodes and their local complications. Localisation of the disease by T cell immunity, due to BCG vaccination is responsible for this and the much lower incidence of haemotological complications such as neurotuberculosis and disseminated disease. In these children, the clinical picture of neurotuberculosis is also modified, with a tendency for more localised involvement of the brain and meninges. Similarly, vaccinated children may present with hepatomegaly, splenomegaly or isolated organ disease. It is important to relearn the new patterns of tuberculosis disease seen in vaccinated, non-malnourished children, and to a lesser extent in children with grade 1 to 2 protein energy malnutrition (PEM). With these limitations of BCG vaccination, other strategies like chemoprophylaxis need multicentric trials in high risk children, in different parts of the country.