During the first months at Auschwitz, sick and exhausted prisoners who could no longer keep up with the required working tempo were usually finished off by the Kapo or, more rarely, carried to the camp hospital. When the SS men decided that hospital rooms were overpopulated, from the summer of 1941 some patients were killed with the “needle”—injections of phenol to the heart. SS doctors selected the doomed patients while inspecting the hospital wards. In addition to overall emaciation (Muselmann), diagnosis of a contagious disease such as tuberculosis or typhus meant a certain death sentence. The doctors held selections of prisoners also in the showers and during “general roll calls”. Larger groups of patients were murdered with Zyklon B in the gas chambers. At first, all prisoners went through selection regardless of ethnicity, but from mid‑1943 selection was performed only on Jews.

(Mini dictionary of terms from the history of Auschwitz)