The World Health Organization (WHO) scheme for classification of dengue severity was evaluated in a three-year study of 1,671 confirmed dengue cases in three Nicaraguan hospitals. The WHO classification of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) was compared with the presence of hemorrhagic manifestations, signs of vascular permeability, marked thrombocytopenia, and shock in 114 infants, 1,211 children, and 346 adults. We found that strict application of the WHO criteria fails to detect a significant number of patients with severe manifestations of dengue, especially in adults.
Balmaseda A, Hammond SN, Pérez MA, Cuadra R, Solano S, Rocha J, Idiaquez W, Harris E. (2005). Short report: assessment of the World Health Organization scheme for classification of dengue severity in Nicaragua. The American journal of tropical medicine and hygiene, 73(6)