Endemic Dengue Associated with the Co-Circulation of Multiple Viral Lineages and Localized Density-Dependent Transmission

Abstract

Dengue is one of the most important infectious diseases of humans and has spread throughout much of the tropical and subtropical world. Despite this widespread dispersal, the determinants of dengue transmission in endemic populations are not well understood, although essential for virus control. To address this issue we performed a phylogeographic analysis of 751 complete genome sequences of dengue 1 virus (DENV-1) sampled from both rural (Dong Thap) and urban (Ho Chi Minh City) populations in southern Viet Nam during the period 2003–2008. We show that DENV-1 in Viet Nam exhibits strong spatial clustering, with likely importation from Cambodia on multiple occasions. Notably, multiple lineages of DENV-1 co-circulated in Ho Chi Minh City. That these lineages emerged at approximately the same time and dispersed over similar spatial regions suggests that they are of broadly equivalent fitness. We also observed an important relationship between the density of the human host population and the dispersion rate of dengue, such that DENV-1 tends to move from urban to rural populations, and that densely populated regions within Ho Chi Minh City act as major transmission foci. Despite these fluid dynamics, the dispersion rates of DENV-1 are relatively low, particularly in Ho Chi Minh City where the virus moves less than an average of 20 km/year. These low rates suggest a major role for mosquito-mediated dispersal, such that DENV-1 does not need to move great distances to infect a new host when there are abundant susceptibles, and imply that control measures should be directed toward the most densely populated urban environments.

Seroprevalence of Neutralizing Antibodies Against Dengue Virus in Two Localities in the State of Morelos, Mexico

“…Because males seem to spend more time away from their houses, the possibility of being infected by dengue in the places that they frequently visit increases. 40 It is intriguing that other studies did not find an association with sex; cultural determinants in these communities could explain this finding. 37,[41][42][43] In regard to occupation, when adjusting by age, locality, and sex, independent workers, senior citizens without salary, disabled individuals, retirees, and housewives were associated with a higher seroprevalence compared with students.…”

Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses?

“…The fact that some recombination most times goes on at various doses has two implications: (1) Pathogens' genetic subdivisions should not be named by the term 'clade', which, strictly speaking, designates evolutionary lines that are totally separated from each other. However, this term, which is most times improper in the context of micropathogen evolution, is widely used in the literature, in parasitic protozoa Su et al, 2012), fungi (McManus and Coleman, 2014;Voelz et al, 2013), bacteria (Chaudhuri and Henderson, 2012;Croucher et al, 2011) and viruses (Liu et al, 2011;Raghwani et al, 2011). This is why we have coined the term 'near-clade' to designate genetic clusters of pathogens that are somewhat blurred by occasional recombination (Tibayrenc and Ayala, 2012).…”

“…The four subtypes are stable since at least 1943, and circulate sympatrically, especially in Latin America and Asia, which provides ample opportunity for mating (Messina et al, 2014). The phylogenetic subtypes are subdivided into 'genotypes' (Weaver and Vasilakis, 2009) or 'clades' (Raghwani et al, 2011) (RD pattern).…”

Uncovering epidemiological dynamics in heterogeneous host populations using phylogenetic methods

“…Characteristics of the phylogeny, identified using statistical methods, reveal epidemiological dynamics. For example, the basic reproductive number of hepatitis C virus [1], the geographical spread of influenza [2,3] and dengue [4], the interaction between transmission groups in HIV [5] or the dynamics of norovirus outbreaks [6] have been investigated.…”