00000000During outbreaks of DEN-1 infections in Taiwan, China, studies have shown that severe gastrointestinal bleeding may occur in persons with preexisting peptic ulcer disease. Unusually severe bleeding can cause death in such cases. The case-fatality rate of DF, however, is less than 1%. It is important to differentiate cases of DF with unusual bleeding from cases of DHF with increased vascular permeability, the latter being characterized by haemoconcentration. In many endemic areas, DF must also be differentiated from chikungunya fever, another vector-borne virus disease of similar epidemiology and overlapping distribution in much of Asia and the Pacific (see Table 2.1).

Dengue haemorrhagic fever

00000000Typical cases of DHF are characterized by four major clinical manifestations: high fever, haemorrhagic phenomena, and often, hepatomegaly and circulatory failure. Moderate to marked thrombocytopenia with concurrent haemoconcentration is a distinctive clinical laboratory finding of DHF. The major pathophysiological change that determines the severity of disease in DHF-and differentiates it from DF-is the leakage of plasma, as manifested by an elevated haematocrit1 (i.e. haemoconcentration), a serous effusion of hypoproteinaemia.

Table 2.2 Non-specific constitutional symptoms
observed in haemorrhagic fever patients with dengue
and chikungunya virus infection

a Modified from Nimmannitya S et al. American journal of tropical medicine and hygiene, 1996, 18: 954-971.
b Statistically significant difference.
c Infants under 6 months.