Pathogenesis and Pathology of Post-Irradiation Infection

It is now well established that total-body irradiation in the lethal and immediate supralethal dose ranges can result in at least two distinct syndromes associated with functional failure of the bowel and of the marrow, respectively (1). These two lethal disease entities can be termed the early or syndrome and the late or bone syndrome. The threshold doses for severe radiation damage to the organs named are different, and hence which syndrome predominates in a given situation depends chiefly on total dosage as well as on the type of radiation employed and the species exposed at a given dose level. As a prelude to discussing the role of infection in deaths after radiation damage, it is to examine closely these symptom complexes and pathological states that may result from total-body exposure to penetrating radiation. This paper does not represent a complete review of the literature, and mention of many works is omitted. A comparison of the two major symptom complexes is made in Table I. Although either apparently can be produced in any mammalian species, the dose to produce either varies with species. In general, the marrow syndrome is predominant throughout the lethal range; only at doses in excess of the LD100/30 do manifestations of the intestinal complex become apparent.4 To produce the early syndrome it is necessary and sufficient (2) to irradiate heavily any large segment of the bowel, and mean