Thrush, or oidial stomatitis, has been comparatively neglected in recent medical literature,1 and its importance, both as a clinical and as an epidemiologic problem, has been too generally minimized. Clinically, it is commonly regarded as an innocuous infection, readily curable or self-limited in duration, whereas it is not uncommonly severe and occasionally fatal; not infrequently it fails to yield even to vigorous treatment, and without treatment it may run a course of many weeks.As a problem of institutional hygiene in the prevention and control of epidemics, particularly in wards for new-born infants, its importance is second only to that of impetigo.It is generally considered that oidial stomatitis is due to contamination from imperfectly sterilized nursing bottles or nipples, from the introduction of unsterile cleansing solutions into the mouth and from the mother's breasts or from the hands of attendants. It is believed that premature, weak, athreptic infants or those suffering from other infectious diseases are especially predisposed to thrush. While we have no reason to dispute any of these beliefs (all of which are doubtless true), none of them offers a solution to the problem presented by the outbreaks of thrush, sporadic at first and later epidemic, in our own hospital. These outbreaks occurred in spite of unquestionably adequate sterilization of all nipples, bottles and solutions entering the infants' mouths and of all clothes and bed linen; in spite of meticulous cleanli¬ ness in handling the babies ; in spite of rigid avoidance of washing or otherwise touching the inside of the babies' mouths ; in spite of careful washing of the mothers' breasts before nursing (although this is admittedly an inadequate procedure) and expressing and discarding the first few drops of milk. It occurred in babies exclusively breast fed, in those almost entirely bottle fed and in those partly breast and partly bottle fed. As a rule, premature infants were spared. Nearly all of the babies in the hospital were healthy and vigorous-
