Table 1.1
Global reports of dengue and dengue haemorrhagic fever, 1956 - 1995^a

a Figures compiled from reports in WHO Regional Offices (AMRO, SEARO & WPRO).

00000000During the 1960s and 1970s, DHF/DSS progressively increased as a health problem, spreading from its primary location in major cities to smaller cities and towns in endemic countries. It established seasonal and cyclical epidemic patterns, with large outbreaks occurring at 2 - 3 year intervals. During this period, 1 070 207 cases and 42 808 deaths were reported, mostly in children. During most of the 1980s, in the endemic countries of China, Indonesia, Malaysia, Myanmar, Philippines, Thailand, and Viet Nam, DHF/DSS spread peripherally, afffecting even rural villages. Exceptionally large outbreaks occurred in Viet Nam (354 517 cases in 1987) and Thailand (174 285 cases in 1987). The total number of people contracting and dying from DHF/DSS reported in all countries of the Western Pacific and South-East Asia Regions for the decade of the 1980s was 1 946 965 and 23 793, respectively. Epidemiologically important new introductions of DHF/DSS were reported in China (1985), Maldives (1985), India (1988), New Caledonia (1988), Sri Lanka (1989) and Tahiti (1989). The experiences in India and Sri Lanka are particularly interesting, because virological surveillance documented the endemic transmission of all four dengue serotypes accompanied by DF cases, but not by DHF/DSS prior to the above-mentioned outbreaks.

00000000In each country of these regions where DHF has become endemic, the sequence has been more or less the same; frequent transmission of dengue virus, first associated with sporadic cases of DHF, followed by DHF epidemics which progressively become more frequent, until DHF cases are seen virtually every year, with major epidemics occurring at 3 - 5 year intervals. All four dengue serotypes are present in these two regions, and increasing international travel serves to introduce new virus strains and serotypes rapidly into susceptible populations. In many countries, DF and DHF are primarily diseases of children, since they represent the largest segment of susceptible individuals within the population at risk. Increasingly, DF, and occasionally DHF, are also seen among travellers. DHF is now a significant public health problem in most of the countries in the tropical areas of the South-East Asia and Western Pacific Regions. The disease is among the ten leading causes of hospitalization and death in children in at least eight tropical Asian countries.