A serious tuberculosis problem still existed in 1920 in many parts of the United States, including Minnesota. Here, approximately 50% of grade school children had primary tuberculosis as manifested by the tuberculin reaction. Clinical extrathoracic tuberculosis was not uncommon among infants and children. Many teen-aged girls and boys died from chronic pulmonary disease. Tuberculosis was prevalent among cattle and many children contracted the disease from them.
Numerous methods of attempting to immunize children against tuberculosis that had been introduced since 1882, including BCG, were carefully studied, but none had proved sufficient to aid in accomplishing the goal we wished to attain. Veterinarians conducted thoroughgoing studies on various so-called immunizing agents, including BCG, among cattle, but all were discarded for lack of efficacy.
The method adopted to control tuberculosis among children consisted of dealing with it as a contagious disease. Children were protected against contagion by isolating and treating adults with open tuberculosis in hospitals and sanatoriums. Many tuberculin testing surveys were conducted and the reactors completely examined, including x-ray film inspection of their chests, particularly the adults. Those with no clinical disease at the moment were periodically examined. Veterinarians practically eradicated tuberculosis from the animal herds.
This fundamental method of control resulted in a tumbling-down of tuberculosis mortality, morbidity and infection attack rates. The mortality rate for all ages dropped from 106.1 (2400 deaths) in 1916 to 13.6 (410 deaths) in 1949. Among infants from birth to 1 year, the mortality rate was 140.4 (68 deaths) in 1916, but only 4.4 (2 deaths) in 1949. Among children from birth to 15 years, the rate was 38.3 (275 deaths) in 1916 and only 1.3 (9 deaths) in 1949. In the age period 10 to 19 years, the mortality rate was 60.4 (268 deaths) in 1916, but only 1.4 (7 deaths) in 1949. Morbidity rates decreased so that in our sanatoriums with long waiting lists in the 1920's, there were 300 to 600 vacancies in the early 1940's, and in 1950 some smaller institutions were closing.
The incidence of primary tuberculosis (tuberculous infection) among grade school children in the largest city decreased from 50% in 1920 to 8% in 1944. There are now many village and rural schools in which no child reacts to tuberculin.
We do not now use or recommend BCG because:
1. The accomplishments by fundamental methods have not been even remotely approached any place in the world where BCG has been used.
2. In places where BCG has been added and tuberculosis mortality has been decreasing, the fundamental methods have also been employed. There is good reason to believe the decrease has been due to the fundamental methods and not to BCG.
3. BCG nullifies the tuberculin test, our best diagnostic and epidemiologic agent.
4. Harmlessness of BCG has not been proved. Indeed, it may be definitely harmful since it is known to kill silicotic animals and those on deficient diets.
5. Attacks of primary or reinfection types of tuberculosis by virulent tubercle bacilli do not result in dependable immunity. Therefore, attempts to produce immunity by establishing lesions with BCG are on a shaky premise.
Immunodiagnostic Tests in the Assessment of Specific Sensitization to M. tuberculosis in Children under the Current Epidemical Situation
