Sensitivity to tuberculin and to a nonmammalian sensitin in Mandalay District, Burma

Delayed hypersensitivity that can be demonstrated with either a strong dose of tuberculin or a conventional dose of a sensitin prepared from certain nonmammalian mycobacteria (mycobacteria of Runyon Groups II and III, e.g., Mycobacterium avium), is known to be highly prevalent in most tropical and many subtropical areas and rare in many temperate zones. Whether such sensitivity interacts significantly with tuberculosis or with leprosy is not known.A study of reactions to tuberculin (PPD-S) and to a sensitin prepared from M. intracellulare (PPD-B) was carried out in villages close to an area in which a clinical trial of the preventive effect of BCG against leprosy was being conducted. The population had not been vaccinated with BCG. Some of the villages were in river valleys that become flooded every year for a long period during the rainy season; others were on slopes above the area subject to floods. The findings showed that sensitivity to the nonmammalian sensitin was prevalent in the area, and thus confirmed previous findings of low-grade tuberculin sensitivity in Burma and neighbouring countries. No difference in this prevalence was found between flooded and nonflooded villages.