Volume 16, Number 1—January 2010 Rapid Displacement of Dengue
Virus Type 1 by Type 4, Pacific Region, 2007–2009 Since
2000–2001, dengue virus type 1 has circulated in the Pacific
region. However, in 2007, type 4 reemerged and has almost
completely displaced the strains of type 1. If only 1 serotype
circulates at any time and is replaced approximately every 5
years, DENV-3 may reappear in 2012. During the past 10–15 years
in the Pacific island nation states, sustained transmission of
only 1 serotype of dengue virus (DENV) has occurred at any given
time (1). This single serotype is in marked contrast to all 4
serotypes that cocirculate in many countries in Southeast Asia
where dengue is endemic. During 1997–2000 in the Pacific region,
the serotype recovered from patients was almost exclusively
DENV-2, but during 2000–2001, <1 year, DENV-2 was displaced by
multiple genotypes of DENV-1 (2). We describe rapid replacement
of DENV-1 by DENV-4 during 2008. In May 2008, an outbreak of a
dengue-like illness began on th