Introduction, Spread, and Establishment of West Nile Virus in the Americas

Abstract

The introduction of West Nile virus (WNV) to North America in 1999 and its subsequent rapid spread across the Americas demonstrated the potential impact of arboviral introductions to new regions, and this was reinforced by the subsequent introductions of chikungunya and Zika viruses. Extensive studies of host–pathogen–vector–environment interactions over the past two decades have illuminated many aspects of the ecology and evolution of WNV and other arboviruses, including the potential for pathogen adaptation to hosts and vectors, the influence of climate, land use and host immunity on transmission ecology, and the difficulty in preventing the establishment of a zoonotic pathogen with abundant wildlife reservoirs. Here, we focus on outstanding questions concerning the introduction, spread, and establishment of WNV in the Americas, and what it can teach us about the future of arboviral introductions. Key gaps in our knowledge include the following: viral adaptation and coevolution of hosts, vectors and the virus; the mechanisms and species involved in the large-scale spatial spread of WNV; how weather modulates WNV transmission; the drivers of large-scale variation in enzootic transmission; the ecology of WNV transmission in Latin America; and the relative roles of each component of host–virus–vector interactions in spatial and temporal variation in WNV transmission. Integrative studies that examine multiple factors and mechanisms simultaneously are needed to advance our knowledge of mechanisms driving transmission.

Canine Distemper Virus (CDV) Transit Through the Americas: Need to Assess the Impact of CDV Infection on Species Conservation

“…However, this same bridge could possibly be used as a transmission bridge for "Multi-Host viruses" such as the CDV (Duque-Valencia et al, 2019b). A similar phenomena has been described for other important viruses such as the West Nile Virus and the Avian Influenza Virus that efficiently use migratory routes, leading to dissemination and intercontinental transmission of viruses in animal populations (Lee et al, 2015;Afanador-Villamizar et al, 2017;Kramer et al, 2019).…”

TMEM41B is a pan-flavivirus host factor

“…Based on our mechanistic studies we hypothesize that TMEM41B is recruited to flavivirus RNA replication complexes to facilitate membrane curvature, which creates a protected environment for viral genome replication. and is now endemic in the United States (Kramer et al, 2019;Roehrig et al, 2002).…”

“…Flaviviruses, members of the Flaviviridae family, are positive sense single-stranded RNA viruses that have caused several notable outbreaks in recent history. For example, West Nile virus (WNV) emerged in New York City in 1999, spread across the continent, and is now endemic in the United States ( Kramer et al, 2019 ; Roehrig et al, 2002 ). Also noteworthy are the recurring yellow fever virus (YFV) outbreaks that occur in sub-Saharan Africa and South America despite the availability of a highly effective vaccine ( Ahmed and Memish, 2017 ).…”

A Comparison of Adult Mosquito Trapping Methods to Assess Potential West Nile Virus Mosquito Vectors in Greece during the Onset of the 2018 Transmission Season

“…West Nile virus (WNV) is an arbovirus belonging to the Japanese encephalitis serocomplex within the Flavivirus genus ( Flaviviridae family) and is the most widespread flavivirus, with circulation worldwide, including the USA and Europe [ 1 , 2 , 3 , 4 ]. Natural transmission of WNV mainly occurs in enzootic cycles between birds and competent ornithophilic mosquito vectors, with avian species being the principal maintenance and amplifying hosts of WNV as many species develop sufficient viremia for onward transmission [ 5 , 6 , 7 ]. Enzootic transmission can continue onward where infected mosquitoes are present in a specific area under suitable environmental conditions [ 8 ].…”