Invasion and Maintenance of Dengue Virus Type 2 and Type 4 in the Americas

Abstract

Dengue virus type 4 (DENV-4) was first reported in the Americas in 1981, where it caused epidemics of dengue fever throughout the region. In the same year, the region's first epidemic of dengue hemorrhagic fever was reported, caused by an Asian strain of dengue virus type 2 (DENV-2) that was distinct from the American subtype circulating previously. Despite the importance of these epidemics, little is known about the rates or determinants of viral spread among island and mainland populations or their directions of movement. We employed a Bayesian coalescent approach to investigate the transmission histories of DENV-2 and DENV-4 since their introduction in 1981 and a parsimony method to assess patterns of strain migration. For both viruses there was an initial invasion phase characterized by an exponential increase in the number of DENV lineages, after which levels of genetic diversity remained constant despite reported fluctuations in DENV-2 and DENV-4 activity. Strikingly, viral lineage numbers increased far more rapidly for DENV-4 than DENV-2, indicative of a more rapid rate of exponential population growth in DENV-4 or a higher rate of geographic dispersal, allowing this virus to move more effectively among localities. We propose that these contrasting dynamics may reflect underlying differences in patterns of host immunity. Despite continued gene flow along particular transmission routes, the overall extent of viral traffic was less than expected under panmixis. Hence, DENV in the Americas has a clear geographic structure that maintains viral diversity between outbreaks.Dengue viruses (DENVs) are single-stranded, positive-sense RNA viruses (family Flaviviridae) that exist as four antigenically distinct serotypes (DENV type 1 [DENV-1] to DENV-4

A Cluster of Dengue Cases in American Missionaries Returning from Haiti, 2010

“…All viruses identified by sequencing in this investigation were most closely related to a DENV-1 isolated in 2007 from the Dominican Republic and Puerto Rico, suggesting that the same virus was circulating on Hispaniola between at least 2007 and 2010. Previous studies have shown that DENV disseminates in the region rapidly but not fast enough to avert geographic clustering 39 ; therefore, the phylogenetic association between DENV-1 isolates from 2007 and 2010 is highly indicative of local and continuous evolution of this lineage. These observations together contribute to the evidence that suggests DENV is endemic in Haiti, although consistent surveillance is necessary to definitively make this conclusion.…”

Lineage II of Southeast Asian/American DENV-2 is Associated with a Severe Dengue Outbreak in the Peruvian Amazon

“…41 previously with DENV-2, but the paucity of full-length DENV-2 sequences from South America makes it difficult to determine the exact location of this introduction. 54 To assess viral replication kinetics in a cell model that more closely reflects replication in vivo, we also monitored the replication of the two lineages daily over 2 days in primary human mo-DCs, which are considered primary targets for DENV infection in humans. [55][56][57] Because two different donors contributed mo-DCs, we initially tested for an effect of donor on viral replication, but we detected neither an interaction between donor and lineage (rmANOVA, df = 1, 18; P = 0.69) nor an overall effect of donor (rmANOVA, df = 1, 18; P = 0.98) on viral replication kinetics at 48 hours post-infection ( Figure 3A and B).…”

Geographical distribution of the association between El Niño South Oscillation and dengue fever in the Americas: a continental analysis using geographical information system-based techniques

“…The mobility of people among Caribbean islands is another factor that no doubt has also contributed to the rapid geographical dispersion of DF serotypes in that region after 1981 (Carrington et al, 2005). In Mexico, the four serotypes were introduced after 1981 and the greater epidemic of 1995-2004 period occurred in 1997.…”