Reemergence of St. Louis Encephalitis Virus, California, 2015

White, Gregory S.; Symmes, Kelly; Sun, Pu; Fang, Ying; Garcia, Sandra; Steiner, Cody; Smith, Kirk; Reisen, William K.; Coffey, Lark L.

doi:10.3201/eid2212.160805

Cited by 32 publications

(36 citation statements)

References 11 publications

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“…2a and b). Collectively, this analysis provides further evidence that the introduction of Genotype III into the southwest United States was due to a single migration event into the southwestern United States, corroborating conclusions made by White et al [13] and Diaz et al [7] .…”

Section: Genetic Relatedness Of 2015 To Historicalsupporting

confidence: 88%

“…Moreover, this was the first outbreak in the United States since the 2001 Louisiana outbreak that resulted in four deaths [14] . The SLEV strain isolated from the 2015 epidemic shared sequence homology with Argentinian strains, placing it within Genotype III, the same genotype that caused the first epidemic in South America [13] [15] . During 2005, Cordoba City, Argentina had 47 probable human cases of SLEV which resulted in 45 hospitalizations and nine deaths [15] .…”

Section: Introductionmentioning

confidence: 99%

“…In 2015, a SLEV outbreak occurred in Maricopa County, Arizona where 23 individuals were infected, 19 of whom developed encephalitis, resulting in two fatalities [12,13] . These were the first cases of SLEV in Arizona in 10 years.…”

Section: Introductionmentioning

confidence: 99%

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Phylogenetic Analysis of St. Louis Encephalitis Virus within Two Southwestern United State Counties: a case for a bulk introduction event into the southwest United States

Ridenour

Cocking

Poidmore

et al. 2020

Preprint

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St. Louis Encephalitis Virus (SLEV) has been seasonally detected within the Culex spp. populations within Maricopa County, Arizona and Coachella Valley, California since an outbreak in Maricopa County in 2015. Previous work revealed that the outbreak was caused by an importation of SLEV genotype III, which had only been detected within Argentina in prior years. However, little is known about when the importation occurred or the population dynamics since its arrival into the southwestern United States. In this study, we wanted to determine if the annual detection of SLEV in Maricopa and Riverside counties is due to enzootic cycling or new importations. To address this question, we analyzed 143 SLEV genomes (138 sequenced as part of this study) using the Bayesian phylogenetic analysis software, BEAST, to estimate the date of arrival into the American Southwest and characterize the underlying population structure of SLEV. Phylogenetic clustering showed that SLEV variants circulating in Arizona and California form two distinct populations with little evidence of transmission among the two populations since the onset of the outbreak. Interestingly, the SLEV variants in Coachella Valley appear to be annually imported from a nearby source, whereas the Arizona population is locally sourced each year. Finally, the earliest representatives of SLEV genotype III in the southwestern US formed a polytomy that includes both California and Arizona samples. We propose that the initial outbreak could have resulted from an introductory population of SLEV, perhaps in one or more bird flocks migrating north in 2013, rather than a single variant introduced by one bird.

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Section: Genetic Relatedness Of 2015 To Historicalsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Phylogenetic Analysis of St. Louis Encephalitis Virus within Two Southwestern United State Counties: a case for a bulk introduction event into the southwest United States

Ridenour

Cocking

Poidmore

et al. 2020

Preprint

Self Cite

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“…In 2015, for example, in addition to the small outbreak in Arizona, SLEV activity unexpectedly was detected through mosquito and sentinel chicken surveillance in southern California after an apparent 11-year absence. 15 Sequencing showed > 99% nucleotide homology between the 2015 California and Arizona isolates, and with a 2005 Argentinian isolate, suggesting a possible introduction of SLEV to the United States from South America at an unknown time. 15 The 2015 outbreak of SLEV disease in Arizona, as well as being the only SLEV disease outbreak reported during the past decade, was also the first known concurrent outbreak of SLEV and WNV disease in the United States.…”

Section: Resultsmentioning

confidence: 96%

St. Louis Encephalitis Virus Disease in the United States, 2003–2017

Curren

Lindsey

Fischer

et al. 2018

The American Journal of Tropical Medicine and Hygiene

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St. Louis encephalitis virus (SLEV), an arthropod-borne flavivirus, can cause disease presentations ranging from mild febrile illness through severe encephalitis. We reviewed U.S. national SLEV surveillance data for 2003 through 2017, including human disease cases and nonhuman infections. Over the 15-year period, 198 counties from 33 states and the District of Columbia reported SLEV activity; 94 (47%) of those counties reported SLEV activity only in nonhuman species. A total of 193 human cases of SLEV disease were reported, including 148 cases of neuroinvasive disease. A median of 10 cases were reported per year. The national average annual incidence of reported neuroinvasive disease cases was 0.03 per million. States with the highest average annual incidence of reported neuroinvasive disease cases were Arkansas, Arizona, and Mississippi. No large outbreaks occurred during the reporting period. The most commonly reported clinical syndromes were encephalitis ( = 116, 60%), febrile illness ( = 35, 18%), and meningitis ( = 25, 13%). Median age of cases was 57 years (range 2-89 years). The case fatality rate was 6% (11/193) and all deaths were among patients aged > 45 years with neuroinvasive disease. Nonhuman surveillance data indicated wider SLEV activity in California, Nevada, and Florida than the human data alone suggested. Prevention depends on community efforts to reduce mosquito populations and personal protective measures to decrease exposure to mosquitoes.

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“…It was proposed that subsequent epidemic lineage expansion occurred in two separate waves, representing emergence near the Palenque region and in the lower Mississippi and Amazon delta. However, independent recent studies show that a variant of SLEV which emerged in Arizona and California in 2015, closely resembled Argentinian isolates made in 2005 [130]. Such south to north dispersion of SLEV, via migratory birds is well known [131], [132] and implies the possibility of a South/Central American origin for SLEV in the Americas.…”

Section: Emergence Of Culex-species Associated Flavivirusesmentioning

confidence: 95%

Emerging arboviruses: Why today?

et al. 2017

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The recent global (re)emergence of arthropod-borne viruses (arboviruses), such as chikungunya and Zika virus, was widely reported in the media as though it was a new phenomenon. This is not the case. Arboviruses and other human microbial pathogens have been (re)emerging for centuries. The major difference today is that arbovirus emergence and dispersion are more rapid and geographically extensive, largely due to intensive growth of global transportation systems, arthropod adaptation to increasing urbanisation, our failure to contain mosquito population density increases and land perturbation. Here we select examples of (re)emerging pathogenic arboviruses and explain the reasons for their emergence and different patterns of dispersal, focusing particularly on the mosquito vectors which are important determinants of arbovirus emergence. We also attempt to identify arboviruses likely to (re)emerge in the future.

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Reemergence of St. Louis Encephalitis Virus, California, 2015

Cited by 32 publications

References 11 publications

Phylogenetic Analysis of St. Louis Encephalitis Virus within Two Southwestern United State Counties: a case for a bulk introduction event into the southwest United States

Phylogenetic Analysis of St. Louis Encephalitis Virus within Two Southwestern United State Counties: a case for a bulk introduction event into the southwest United States

St. Louis Encephalitis Virus Disease in the United States, 2003–2017

Emerging arboviruses: Why today?

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