Epidemiological information on leprosy in the Singu area of Upper Burma.

In the course of a WHO trial designed to evaluate the possible protective action of BCG vaccine against leprosy, a longitudinal epidemiological study of the whole population was carried out in an area of very high endemicity in Burma from 1964 to 1976. Two mass surveys of the whole population with an interval of 4 years and annual re-examination of the 28 000 children (0-14 years) in the BCG trial were carried out. The data collected yielded important information about general prevalence and yearly incidence of the disease as well as on sex, age, and classification of cases. The general prevalence rate declined from 32.6 per 1000 in the first survey to 25.2 per 1000 in the second. The number of cases among males was significantly higher than among females. Incidence rate among contacts of already known cases was 9.8 per 1000 person-years. The estimated yearly incidence among non-contacts was 5.9 per 1000. Prevalence rates reached a peak in the 20-39-year age group. The prevalence rate of multibacillary patients also reached a peak in the same age bracket. It is stressed that a further period of epidemiological surveillance will be essential in order to have a correct estimate of the expected number of new infections, especially multibacillary cases, in the 20-39-year group. The value of this information is considered unique for planning and programming of future control activities.

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.