Febrile neutropenia is the evelopment of fever, often with other signs of infection, in a patient with neutropenia, an abnormally low number of neutrophil granulocytes (a type of white blood cell) in the blood. The term neutropenic sepsis is also applied, although it tends to be reserved for patients who are more unwell. Fever is actually caused by infection in 50% of cases, and bacteremia (bacteria in the bloodstream) may be present in as many as 20% of all patients with an absolute neutrophil count under 1.0.