The development of tuberculosis in Afro-Asian immigrants.

Tuberculin testing and a chest x-ray have been carried out on 1492 Asian immigrants. Analysis has shown that the percentage tuberculin positive reactions does not increase with increasing length of stay in this country. Few arrive with active disease but after 3 months residence there is a steady incidence of tuberculosis morbidity. Apparently immigrants in the Harrow area arrive with past tuberculous infection, manifest only by a positive tuberculin test, and subsequently suffer endogenous exacerbation.