Bodey et al. first described the quantitative association between leukocyte counts and the incidence of infection in a study of acute leukemia in 1986.

In 1966, Bodey et al. first described the quantitative association between leukocyte counts and the incidence of infection in a study of acute leukemia which demonstrated that the risk and the type of infection are related to the severity and duration of granulocytopenia.^[1] Infection risk begins to increase when the absolute neutrophil count (ANC) decreases to less than 1000 cells/mm³ and rises markedly when the ANC drops to less than 500 cells/mm³. When the causative pathogen is identifiable, bacterial or viral etiology predominates within the first seven days of neutropenic fever, while infection with antibiotic-resistant bacteria or invasive fungi occurs more often in the setting of protracted neutropenia.^[2]