Purpura Variolosa

Smallpox in its endemic form in this country (variola minor or alastrim) is seen sporadically and as a rather mild disease. Variola major, on the other hand, is a serious epidemic disease, but fortunately is experienced rarely within the continental limits of the United States. In fact, in recent years it has occurred so infrequently that the experience gained in one outbreak is generally lost or memory of it has faded so completely as to be quite useless by the time the next outbreak is encountered. One of the more severe, but little appreciated, forms of variola major is true hemorrhagic or "black" smallpox (purpura variolosa) with a reported mortality rate of 100%o. During the early part of 1946 the Seattle-King County area of the state of Washington had the misfortune to experience an outbreak of 65 cases of variola major with 20 deaths, among which were included the six cases of purpura variolosa which form the nucleus for this paper. Since the epidemiological and clinical details of this outbreak have been given elsewhere,"6'l' suffice it to say that the smallpox virus was introduced into a susceptible population by a soldier returning from the Orient. To those of us who were caring for the clinical cases of smallpox, purpura variolosa constituted a real diagnostic problem. The observations to be set forth were made by ust and are not new, for the clinical descriptions of smallpox made three-quarters of a century and more ago are surprisingly complete and accurate, but the present observers' lack of actual clinical experience with smallpox in its severe classical form and the paucity of pertinent observations in the recent medical literature with regard to this problem have made it seem desirable to set forth our experiences with true hemorrhagic smallpox in some detail. In order to appreciate purpura variolosa, it is necessary to visualize and emphasize the extraordinarily orderly progression of the clinical course of smallpox. It will be recalled that one of the distinguishing characteristics