The practice in vogue for the control of diphtheria outbreaks is based on bacteriologic control of all contacts and convalescents. Those yielding cultures of the Klebs-Loeffler bacillus are isolated and kept in isolation until negative cultural results are obtained. Failing this result, the virulence test is relied on as a criterion of safety. Thus the laboratory leads the way, field work being subordinated to it.
Two years' practical experience, both as bacteriologist and as epidemiologist, has convinced me of the fallacy of depending primarily on laboratory tests.
Carriers are of two types, pharyngeal and nasal. The former, constituting less than one fourth of all carriers, show acute hyperemia superimposed on chronic pharyngeal hypertrophy. The culture result is positive and there is a history of an attack of diphtheria.The second or nasal type is characteristic. There is a bloody, purulent anterior nasal discharge, usually unilateral, with excoriation of the