1998 - Singapore

18 August 1998

Disease Outbreak Reported

In recent years, dengue has become a major international public health concern. Many countries/areas in Asia have been experiencing unusually high levels of dengue/dengue haemorrhagic fever activity in 1998.

Over the past 2 decades, 29 out of the 37 countries/areas in the WHO Western Pacific Region have reported dengue cases. The disease has been reported more or less annually by 15 countries, including Cambodia, China, Lao People's Democratic Republic, Malaysia, the Philippines, Singapore, Viet Nam and several Pacific island countries/areas. During 1993-1997, a total of 552 088 cases was reported from the Region. Of these, 70% were reported from Viet Nam alone. The case-fatality rate (CFR) has been declining in most of the endemic countries in the Region over the last 2 decades due to better understanding of the pathogenesis and improvement in case management. The overall CFR in the Region is now less than 1%. However, in some countries the CFR still exceeds 4% due to factors such as admission to hospital when the disease is in an advanced state.

In newly industrialized countries such as Malaysia and Singapore, dengue incidence once declined owing to successful vector control programmes, but a resurgence in the number of cases has been reported since 1994. In the Pacific island countries/areas, the reappearence of dengue type 2 was confirmed in 1996 for the first time since the 1980s.

The occurrence of dengue cases in most countries of the WHO Western Pacific Region reaches its peak during the period June-November each year. The level of activity so far in 1998 has been considerably higher than in previous years. A major contributing factor may be changes in weather patterns, such as the El Niño phenomenon.