Using Avian Surveillance in Ecuador to Assess the Imminence of West Nile Virus Incursion to Galápagos
Infectious disease emergence represents a global threat to human, agricultural animal and wildlife health. West Nile virus (WNV) first emerged in the Americas in 1999 following its introduction to New York from the Old World. This flavivirus rapidly spread across much of North America, causing human, equine and avian mortalities and population declines of multiple wild bird species. It has now spread to Central and South America, and there is concern that the virus will reach the Galápagos Islands, a UNESCO World Heritage Site famous for its unique biodiversity, with potentially catastrophic results. Here, we use wild bird surveillance to examine the current WNV status in the Galapagos Islands and around the Ecuadorian city of Guayaquil (the main air and sea port serving Galápagos). We conducted serosurveys of wild birds on three Galápagos Islands (Baltra, San Cristobal and Santa Cruz) with direct transport links to the South American continent. In addition, dead birds killed by car collisions on Santa Cruz were tested for WNV infection. On mainland Ecuador, serosurveys of wild birds were conducted at three sites around Guayaquil. No evidence of WNV seropositivity or infection was detected. Although wider testing is recommended on the mainland, the study highlights a limit of WNV spread within South America. Our results indicate the continued absence of WNV on Galápagos and suggest the current likelihood of human-mediated transport of WNV to Galápagos to be low. The risk of emergence will almost certainly increase over time, however, and stringent biosecurity and surveillance measures should be put in place to minimise the risk of the introduction of WNV (and other alien pathogens) to Galápagos.
Keywordsemerging infectious disease West Nile virus surveillance avifauna Ecuador Galápagos Infection prevalence
This work was possible due to the generous funding of the Natural Environment Research Council, and to the 2011 Daisy Balloch Award (Zoological Society London—Institute of Zoology) awarded to GE. Additional financial support was provided by Darwin Initiative Grant EIDPO15 to SG, AC and Virna Cedeño. We thank Virna Cedeño for contributions instrumental to establishing the Galapagos Genetics Epidemiology and Pathology Laboratory, which made this work and other studies investigating disease emergence in Galapagos Islands possible. We are grateful to both the Galápagos National Park and the Ministry of Environment (MAE Guayaquil) for permissions to conduct sampling. Thank you to the administrators of Lago de Capeira, Pantanal Zoo, Parque Histórico Guayaquil and Fundación Ecológica Andrade for allowing us to collect on their properties. The field assistance of Julian Correa Pérez (UEES), Grace Loyola-Herrera and Pamela Martinez was greatly appreciated. Thank you also to Alan Dupuis for laboratory support and reviewing a draft manuscript.
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