Children infected with tubercle bacilli under the age of 12 years occasionally develop the acute reinfection type of tuberculosis, such as miliary disease, pneumonia, meningitis, pericarditis, pleuritis, peritonitis and synovitis. During this age period the chronic reinfection type of disease occasionally develops in the extrathoracic organs such as the bones and joints, but the lungs are involved with great rarity. The reinfection type of chronic pulmonary tuberculosis begins to make its appearance among tuberculin reactors in the early teen ages and increases in frequency with the decades. Since this fact was established the previous enthusiasm for examination of school children has waned; indeed, in some places such work has been abandoned. This is an extremely unfortunate situation and is without practical or scientific foundation.
Every child who reacts to tuberculin has primary tuberculosis (tuberculous infection). This disease begins with the first focalization of tubercle bacilli by neutrophils. From this stage