Latent Infections.

In the contemporary literature which deals with the infectious diseases, the designation "symptomless infection" is used with increasing frequency. The question immediately arises: Do recent observations, experimental and clinical, and new epidemiologic experiences justify the creation of this term? Is it not likely that a new word has been coined to describe the well-known state of "latent infections"? No one will deny that the usual signs of an infectious malady-the manifest and latent stages-may be readily bridged by the so called rudimentary or "abortive" forms of the disease. In other words, the symptomatology of an infection oscillates between the frank, clinically typical disease and the unrecognizable reaction. The persistence of a disease agent from the time of its entry into a host or the "symptomless" state of infection, which may follow clinical recovery, has been described, since the discovery of the tubercle bacillus by R. Koch in the tissues of apparently healthy individuals, as a "latent infection." Furthermore, one was satisfied to characterize certain atypical forms of a disease as "abortive" when it was believed that the disease-producing virus multiplied only to a moderate extent and consequently induced feeble reactions or no symptoms at all. The recognition of the "abortive" cases has gradually led to a broader conception of the infectious maladies. Since a disease is generally considered from an etiologic point of view, it is not surprising to note the descriptions of scarlet fever without a rash and poliomyelitis without paralysis. Whether or not the variant types of a disease are truly "abortive" forms has certainly not been determined for a great many infections. In fact, the