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Results: 5

1.
PLoS Pathog. 2013;9(8):e1003570. doi: 10.1371/journal.ppat.1003570. Epub 2013 Aug 29.

Influenza a virus migration and persistence in North American wild birds.

Author information

  • 1Laboratory of Virus Evolution, Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, Singapore.

Abstract

Wild birds have been implicated in the emergence of human and livestock influenza. The successful prediction of viral spread and disease emergence, as well as formulation of preparedness plans have been hampered by a critical lack of knowledge of viral movements between different host populations. The patterns of viral spread and subsequent risk posed by wild bird viruses therefore remain unpredictable. Here we analyze genomic data, including 287 newly sequenced avian influenza A virus (AIV) samples isolated over a 34-year period of continuous systematic surveillance of North American migratory birds. We use a Bayesian statistical framework to test hypotheses of viral migration, population structure and patterns of genetic reassortment. Our results reveal that despite the high prevalence of Charadriiformes infected in Delaware Bay this host population does not appear to significantly contribute to the North American AIV diversity sampled in Anseriformes. In contrast, influenza viruses sampled from Anseriformes in Alberta are representative of the AIV diversity circulating in North American Anseriformes. While AIV may be restricted to specific migratory flyways over short time frames, our large-scale analysis showed that the long-term persistence of AIV was independent of bird flyways with migration between populations throughout North America. Analysis of long-term surveillance data provides vital insights to develop appropriately informed predictive models critical for pandemic preparedness and livestock protection.

PMID:
24009503
[PubMed - indexed for MEDLINE]
PMCID:
PMC3757048
Free PMC Article
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2.
J Med Entomol. 2012 Sep;49(5):1092-102.

Host preference of the arbovirus vector Culex erraticus (Diptera: Culicidae) at Sonso Lake, Cauca Valley Department, Colombia.

Author information

  • 1Department of Tropical Medicine, Tulane University, 1440 Canal St, Suite 2210, New Orleans, LA 70112, USA. ian.mendenhall@duke-nus.edu.sg

Abstract

Culex erraticus (Dyar & Knab) is a competent vector of Eastern equine encephalitis virus and subtype IC Venezuelan equine encephalitis virus, and both St. Louis encephalitis virus and West Nile virus have been isolated from field-collected specimens. Previous bloodmeal analysis studies have shown this species to be a generalist, feeding on a variety of mammals, birds, reptiles, and amphibians. This behavior can bridge arboviral transmission across different vertebrate groups. Our study examined the host preference of Cx. erraticus at Sonso Lake in Colombia. From July to August 2008, blood-engorged mosquitoes were collected from resting boxes, while vertebrate abundance was determined to calculate host preference. Based on mitochondrial DNA analysis of bloodmeals, birds were the predominant hosts (57.6%), followed by mammals (30.8%), and reptiles (6.7%); 9.5% of the bloodmeals were mixed. The most commonly fed upon species were: limpkin, black-crowned night-heron, striated heron, human, and capybara. Forage ratios showed the least bittern, limpkin, Cocoi heron, striated heron, capybara, and black-crowned night heron were preferred hosts across all vertebrates. Of the available avifauna, the least bittern, limpkin, striated heron, Cocoi heron, and black-crowned night heron were preferred, whereas the bare faced ibis, great egret, snowy egret, and cattle egret were under-used. This study shows that while Cx. erraticus is an opportunistic feeder, using diverse vertebrate hosts in the environment, certain avian species are targeted preferentially for bloodmeals.

PMID:
23025191
[PubMed - indexed for MEDLINE]
3.
J Med Entomol. 2012 May;49(3):522-34.

Genetic structure of Culex erraticus populations across the Americas.

Author information

  • 1Department of Tropical Medicine, Tulane University, New Orleans, LA 70112, USA. ian.mendenhall@duke-nus.edu.sg

Abstract

Culex erraticus (Dyar & Knab) is a potential competent vector for several arboviruses such as Eastern and Venezuelan equine encephalitis viruses and West Nile virus. It therefore may play a role in the maintenance and spread of viral populations in areas of concern, including the United States where it occurs in >33 states. However, little information is available on potential barriers to movement across the species' distribution. Here, we analyze genetic variation among Cx. erraticus collected from Colombia, Guatemala, and nine locations in the United States to better understand population structure and connectivity. Comparative sequence analysis of the second internal transcribed spacer and mitochondrial NADH dehydrogenase genes identified two major lineages of sampled populations. One lineage represented the central and eastern United States, whereas the other corresponded to Central America, South America, and the western United States. Hierarchical analysis of genetic variation provided further evidence of regional population structure, although the majority of genetic variation was found to reside within populations, suggestive of large population sizes. Although significant physical barriers such as the Chihuahuan Desert probably constrain the spread of Cx. erraticus, large population sizes and connectivity within regions remain important risk factors that probably contribute to the movement of arboviruses within and between these regions.

PMID:
22679859
[PubMed - indexed for MEDLINE]

Publication Types, MeSH Terms, Secondary Source ID, Grant Support

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4.
BMC Vet Res. 2011 Aug 11;7:43. doi: 10.1186/1746-6148-7-43.

The impact of West Nile virus on the abundance of selected North American birds.

Author information

  • 1Department of Epidemiology, Tulane School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA. ivo.foppa@gmail.com

Abstract

BACKGROUND:

The emergence of West Nile virus (WNV) in North America has been associated with high mortality in the native avifauna and has raised concerns about the long-term impact of WNV on bird populations. Here, we present results from a longitudinal analysis of annual counts of six bird species, using North American Breeding Bird Survey data from ten states (1994 to 2010). We fit overdispersed Poisson models to annual counts. Counts from successive years were linked by an autoregressive process that depended on WNV transmission intensity (annual West Nile neuroinvasive disease reports) and was adjusted by El Niño Southern Oscillation events. These models were fit using a Markov chain Monte Carlo algorithm.

RESULTS:

Model fit was mostly excellent, especially for American Crows, for which our models explained between 26% and 81% of the observed variance. The impact of WNV on bird populations was quantitatively evaluated by contrasting hypothetical count trajectories (omission of WNV) with observed counts. Populations of American crows were most consistently affected with a substantial cumulative impact in six of ten states. The largest negative impact, almost 60%, was found in Illinois. A regionally substantial decline was also seen for American Robins and House Sparrows, while the other species appeared unaffected.

CONCLUSIONS:

Our results confirm findings from previous studies that single out American Crows as the species most vulnerable to WNV infection. We discuss strengths and limitations of this and other methods for quantifying the impact of WNV on bird populations.

PMID:
21831324
[PubMed - indexed for MEDLINE]
PMCID:
PMC3163188
Free PMC Article
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5.
J Am Mosq Control Assoc. 2011 Jun;27(2):148.

First record of Culex (Anoedioporpa) restrictor from Colombia.

Author information

  • 1Department of Tropical Medicine, Tulane University, New Orleans, LA 70112, USA.

Abstract

We report the first record of Culex (Anoedioporpa) restrictor collected from a tree hole in the Cauca Valley, Colombia, in 2006.

PMID:
21805847
[PubMed - indexed for MEDLINE]

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