Dengue--how best to classify it

Abstract

Dengue has emerged as a major public health problem worldwide. Dengue virus infection causes a wide range of clinical manifestations. Since the 1970s, clinical dengue has been classified according to the World Health Organization guideline as dengue fever and dengue hemorrhagic fever. The classification has been criticized with regard to its usefulness and its applicability. In 2009, the World Health Organization issued a new guideline that classifies clinical dengue as dengue and severe dengue. The 2009 classification differs significantly from the previous classification in both conceptual and practical levels. The impacts of the new classification on clinical practice, dengue research, and public health policy are discussed.

Figure 1.

Dengue classification according to the World Health Organization guidelines issued in 1975 and 1997. Dengue is classified as (1) undifferentiated fever, (2) dengue fever (DF), and (3) dengue hemorrhagic fever (DHF). In addition to fever and at least 2 clinical findings, diagnosis of DF requires epidemiological or laboratory evidence supporting a dengue virus infection. To meet a case definition of DHF, all 4 criteria are required: (1) fever, (2) hemorrhagic manifestations, (3) thrombocytopenia (platelet count, ≤100000 platelets/mm³), and (4) evidence of plasma leakage. Diagnosis of DHF does not require laboratory support.

Figure 2.

Dengue classification according to the World Health Organization guidelines issued in 2009. Dengue is classified as dengue with or without warning signs and severe dengue. Diagnosis of dengue requires the presence of fever and at least 2 clinical findings or any warning signs. Epidemiological or laboratory evidence is required to make the diagnosis. Severe dengue is defined as dengue with any of the following: (1) severe plasma leakage leading to shock or respiratory distress, (2) severe hemorrhage, or (3) any organ failure.