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Source: World Health Organization and the Pacific Public Health Network

Many parts of south-east Asia (Malaysia, Taiwan [China], Cambodia, Viet Nam, Thailand, Philippines, Indonesia, Myanmar), the western Pacific (Guam, Cook Islands, Fiji, New Caledonia, Kiribati) and Latin America (Brazil, Venezuela, Colombia) have been experiencing unusually high levels of dengue/dengue haemorrhagic fever activity. Although there is often a seasonal increase in dengue in some of these places at this time of the year, the level of activity in 1998 is considerably higher than in previous years. Changes in weather patterns as a result of the El Nino phenomenon are thought to be a major contributing factor.

Unless more effective measures are taken to control the main vector, Aedes aegypti, in these and other countries/areas, dengue will continue to be a growing problem in tropical and subtropical regions of the world. Essential elements of an effective program are integrated mosquito control with community and intersectoral involvement, vector surveillance for monitoring and evaluation, emergency preparedness, capacity building and training, and applied research.

Viet Nam

A total of 16,647 cases of dengue/dengue haemorraghic fever with 55 deaths (case fatality rate = 0.3%) has been reported since the beginning of 1998. The incidence has more than doubled compared with the same period last year. As the traditional peak season for dengue (June to November) has only just started a major epidemic is expected to occur. While dengue 2 virus was the most prevalent strain in 1997, early data suggests that dengue 3 virus predominates this year.

Malaysia

Since the beginning of 1998 there has been a total of 5,337 cases (including 194 cases of dengue haemorraghic fever) and five deaths reported The number of cases is similar to that reported for the same period last year.

Indonesia

There has been a rapid increase recently in dengue/dengue haemorrhagic fever cases and all provinces of the country are now affected. As of 5 May a total of 32,665 cases with 774 deaths had been reported. This number of cases is considerably higher than for the same period last year. It is expected that cases will continue to increase during the peak season of May to July.

Brazil

This year Brazil is experiencing the highest levels of dengue transmission in its history. A total of 234,828 cases was reported during the first four months of 1998, compared with 159,965 cases during the same period in 1997. There have been 60 cases of dengue haemorrhagic fever reported and eight deaths. Both dengue 1 and dengue 2 viruses are circulating.

Tonga

Since February 1998 the Ministry of Health in Tonga has reported a total of 438 suspected cases of dengue. Of these 220 were serologically tested and 70 confirmed. Included was a six year old child with confirmed dengue who died. There is little evidence of dengue in outer islands. The number of cases has fallen in recent weeks. The virus has been identified as dengue virus type 2.

This article was published in Communicable Diseases Intelligence Vol 22 No 6, 11 June 1998.