ABSTRACT
The clinical spectrum of dengue fever ranges from asymptomatic infection through severe haemorrhage and sudden fatal shock. Increased capillary permeability is the diagnostic feature of dengue haemorrhagic fever (DHF). The pathophysiology of DHF/dengue shock syndrome (DSS) is related to sequential infection with different serotypes of the virus, variations in virus virulence, interaction of the virus with environmental or host factors and a combination of various risk factors. Infection due to low virulence strains is assumed to be the reason for the infrequent incidence of serious dengue disease in India. Since all four serotypes of the dengue virus have been implicated in various outbreaks in this country and several outbreaks of DHF/DSS have been recorded since the first report in 1963, further epidemics of the disease are likely. The situation is aggravated by the recent emergence of DHF/DSS in Sri Lanka. In view of the potential of this disease to spread, effective preventive and control measures should be a priority.