Emerging disease surveillance and response

Dengue in the Western Pacific Region

Dengue is the fastest emerging arboviral infection. The maximum burden is borne by countries of the Asia Pacific Region. Among the estimated 2.5 billion people at risk globally, about 1.8 billion—more than 70%—reside in Asia Pacific countries. Recent estimate made by Pediatric Dengue Vaccine Initiative however showed that population at risk is about 3.6 billion people (55% of world population) in 124 endemic countries1. Its epidemiology is rapidly evolving, with increased frequency of outbreaks and expansion to new geographical areas that were previously unaffected. Mortality is highest during the initial period of the outbreak or epidemic. Children in particular are at high risk of mortality as a result of complications and lack of access to prompt treatment.

Reports to WPRO showed that continues its increasing trend. Few years after the large dengue outbreaks in 1998, Member States in the Western Pacific started to report increased number of dengue cases. Annual reported dengue cases were around 100 000 cases in 2001-2002. The figures gradually increased to 150 000-170 000 cases annually during the period 2003-2006. Since 2007, the region reported over 200,000 dengue cases each year.

In 2009, there were 242, 424 dengue cases and 785 dengue deaths were reported in 25 out of 37 countries and territories in the region. Countries that were hardest hit include: Cambodia (11 699 cases, 38 deaths), Malaysia (41 486 cases, 88 deaths), Philippines (57 819 cases, 548 deaths) and Vietnam (105 370 cases, 87 deaths). Dengue outbreaks appear to be more frequent not only in endemic countries of the Asia sub-region of the Western – Pacific region but also in countries of Pacific sub-region where it was often known to have been contracted off-island. Fourteen Pacific Island Countries and territories reported experiencing dengue outbreaks in 2009. Many of them reported high incidence rates of dengue cases. These include American Samoa (643.6/100 000 inhabitants), Cook Islands (1 089.7/100 000 inhabitants), French Polynesia (921.6/100 000 inhabitants), New Caledonia (3 442.6/100 000 inhabitants), Tonga (262.5/100 000 inhabitants). American Samoa, New Caledonia and Tonga also reported dengue outbreaks with high incidence rate in 2008.

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