Low prevalence of avian influenza virus in shorebirds on the Pacific Coast of North America

Samuel A. Iverson, John Y. Takekawa, Steven Schwarzbach, Carol J. Cardona, Nils Warnock, Mary Anne Bishop, Greg A. Schirato, Sara Paroulek, Joshua T. Ackerman, Hon Ip, Walter M. Boyce

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The emergence of highly pathogenic avian influenza (HPAI) H5N1 has elevated concerns about wild birds as virus hosts; however, little is known about the ecological and epidemiological factors of transmission by shorebirds. Here we summarize results for 2,773 shorebirds that were live-trapped on the Pacific coast of the United States during 2006-2007 and tested for avian influenza virus using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and virus isolation. As was the case throughout North America, HPAI H5N1 was not detected in shorebirds during this interval. Contrary to other wild bird groups, most notably waterfowl, the prevalence of even low pathogenicity virus among shorebirds in our study areas in California, Washington, and Alaska was extremely low (0.5%). Virus was detected by RT-PCR from four different species, including, Dunlin (Calidris alpina; N = 3), Western Sandpiper (C. mauri; N = 8), Long-billed Dowitcher (Limnodromus scolopaceus; N = 1), and American Avocet (Recurvirostra americana; N = 1), with the detections in the latter three constituting the first published records for these birds. Based on studies in the eastern United States, we expected, but did not detect (H1 = 1.6, P = 0.21) elevated avian influenza prevalence among shorebirds during spring migration. Diagnostic tests, which were designed to evaluate testing and sampling methods, indicated poor functioning of traditional virus isolation methods and no improvement in detection likelihood by collecting oropharyngeal swabs in addition to cloacal swab samples for low pathogenicity viruses (Z1 = 0.7, P = 0.48).

Original languageEnglish (US)
Pages (from-to)602-610
Number of pages9
JournalWaterbirds
Volume31
Issue number4
DOIs
StatePublished - Dec 1 2008

Keywords

  • Charadriiformes
  • H5N1
  • Pacific Flyway
  • United States
  • avian influenza
  • cloacal swabs
  • epidemiology
  • oropharyngeal swabs
  • shorebirds
  • waders
  • wild birds

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