Which phase of Acute Radiation Syndrome involves clinical symptoms in major organ systems such as hematopoietic, gastrointestinal, and central nervous systems?

• A. Prodromal Phase
• B. Latent Phase
• C. Manifest Illness Phase
• D. Recovery or Death Phase

Answer: (C)

Clinical illness across major organ systems appears once radiation damage becomes visibly active in the body—the manifest illness phase. After an initial prodromal period with nonspecific symptoms and a short latent phase, the body’s damage to bone marrow (hematopoietic), the lining of the GI tract, and, at higher doses, the central nervous system leads to clear, system-wide illness. You’ll see signs like infections and bleeding from marrow suppression, severe GI symptoms such as vomiting and diarrhea with dehydration, and at very high doses, neurologic changes. The prodromal phase is mainly early, nonspecific symptoms; the latent phase is largely symptom-free; and recovery or death is the eventual outcome, not the phase where these organ-system illnesses are first evident.