Droplet Infection and its Prevention by the Face Mask

In recent years the spread of contagious diseases has been combated largely by measures calculated to limit the more or less direct passage or carriage of infectious materials from the sick to others. The term contact infection has often been employed to designate all such instances of direct passage or carriage, although actual contact did not always occur. Aerial transfer of infectious materials has been applied to a wide distribution of disease agents through air at considerable distances, and especially to dissemination through dust. This form of transfer has been shown to play so small a part in the spread of contagious diseases as to be practically negligible. The part played in the transfer of infections by mouth droplets driven out in forced expiratory efforts has not usually received sufficient attention. The tendency of those who have insisted on the almost exclusive role of contact infection in the spread of contagious diseases has been to include droplet infection among the forms of contact infection, but to assign it a minor part. The factor of distance which is a most important one has been largely ignored. Recent experiences have served to emphasize the ease with which infections may be transferred through mouth droplets when people are brought into intimate association in military establishments. The danger of transfer in this way of secondary infecting organisms which cᵘse most complications in cases of contagious diseases has long been appreciated by physicians who have dealt with these diseases in institu tions, and they have insisted on the isolation of individuals who have active secondary infections from others who have the uncomplicated disease. Secondary infections are transferred in the same manner as the primary disease in most instances. Our recent army experiences have emphasized the fact that carriers and droplet infections are two factors which must receive a large share of attention in the management of contagious diseases.