The basis for a tuberculosis control program in Mexico.

Roughly 120,000 persons over 15 years of age in Mexico are believed to have tuberculosis.6 About 50 per cent of these have been registered with the nation’s health services, the location of the remainder being unknown. Furthermore, in the past a large share of those registered have abandoned drug therapy before the end of six months, and only about half have received the benefits of the full one-year course of treatment. This general situation has been accompanied by high levels of early exposure to the disease. For example, surveys made by the Ministry of Health and Welfare and the Bureau of School Hygiene in 1963 indicated a level of exposure reaching 15.3 per cent in the O-14 age groupbased on a skin reaction of 6 mm or more to 2 Units of PPD-tuberculin (RT 23),7 as shown in Figure 1. Among the population as a whole it is