The Causes of Relapse in Quiescent Cases of Pulmonary Tuberculosis *

DEFINITIONS OF THE TERM "QUIESCENT" THE British definiitioni until 1947 was as follows:-"'Cases which have no symptoms of tuberculosis and nio signis of tuberculous disease, except such as are compatible with a completely-healed lesionl, and in wllich sputum, if present, is free from tubercle bacilli." 'I[hle lnew definiition of the Joint 'I'uberculosis Council is: "Cases in which the genieral conditioon and exercise tolerance are good, having regardl to the extent of the lesioni; which show no evidence of toxanmia; in wvhichl no tubercle bacilli have been found on three consecutive monthly examinations by staineid filmi; and in whiclh clhang-es revealed by otlher clinical investigations and by serial skiagramiis point to retrogression of' the tuberCulous lesion." 'Ihe Midhurstl (lefinitioni, whichi requires special niention onl accounit of the impor-tanice of the Midlhurst figuLres, is different, as the term "I)isease Arrested'" is the c(luivalenit of quiescent and is define(d as lfollows:-'(Ielneral health completely restored in every respect, withlout any sig,n of, disease of the lungs, except such as is compaitible with a completely-lheledl lesion ; sputumi, if still presenit, free from tubercle bacilli." 'I'lhe American nomenclaturc3 is enltirel, (lilferent, being as followx:s '.'RRESTEI.-CO11StitUtiOnllII sYnmptotms absen1t. Sputunm, il any, m11uSt We Coll-celltrate(l and found microscopicallk negative f'or tubercle bacilli. Lesions stationary ancI apparently healed, according to X-ray examination ; 11o evidence of pulmoonary cavity. These cond(litionis slhall have existed for a perio(d of six montlhs, durinig the last two of wNhich the paticnt has beenl takinig oone houL's walking exercise twice daily, or its equivalent.' 'APPARENTLY ARRESTED.-Constitutional sN-mptoms absent. Sputumii, if anyl, m1Rust be concentrated and fouLnd microscopically negative for tubercle bac-illi.