BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, researchlibraries, and research funders in the common goal of maximizing access to critical research.

Experimental West Nile Virus Infection in Aigamo Ducks, A Cross betweenWild Ducks (Anas platyrhynchos) and Domestic Ducks (Anas platyrhynchos var.domesticus)Author(s): Hiroaki Shirafuji, Katsushi Kanehira, Masanori Kubo, Tomoyuki Shibahara, and TsugihikoKamioSource: Avian Diseases Digest, 4(2):e11-e12. 2009.Published By: American Association of Avian PathologistsDOI: http://dx.doi.org/10.1637/8863.1URL: http://www.bioone.org/doi/full/10.1637/8863.1

BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, andenvironmental sciences. BioOne provides a sustainable online platform for over 170 journals and books publishedby nonprofit societies, associations, museums, institutions, and presses.

Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance ofBioOne’s Terms of Use, available at www.bioone.org/page/terms_of_use.

Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiriesor rights and permissions requests should be directed to the individual publisher as copyright holder.

EXPERIMENTAL WEST NILE VIRUS INFECTION IN AIGAMO DUCKS, A CROSS BETWEEN WILDDUCKS (ANAS PLATYRHYNCHOS) AND DOMESTIC DUCKS

(ANAS PLATYRHYNCHOS VAR. DOMESTICUS)

HIROAKI SHIRAFUJI, KATSUSHI KANEHIRA, MASANORI KUBO, TOMOYUKI SHIBAHARA, AND TSUGIHIKO KAMIO

Contact Address: shirah@affrc.go.jp

Important FindingsThe results of this study suggest that West Nile virus (WNV)-

infected aigamo ducks can transmit WNV (Figures 1–3). Althoughaigamo ducks are reared in East Asia where WNV is an exoticpathogen, the virus could be introduced and spread there in the future.

Significance of FindingsThe study results suggest that if WNV is introduced into East Asia,

aigamo ducks could be affected and involved in its transmission, whichwould cause economic losses in aigamo duck operations. Thus, it wouldbe important to take precautions against introducing WNV bymonitoring or surveillance. In addition, measures should be prepared toprevent infection, such as mosquito control for aigamo duck operations.

Additional InformationWNV, one of the most widespread flaviviruses, cycles between

birds and mosquitoes. Although the virus has not been detected inEast Asia, once introduced there, it would spread rapidly and becomeendemic for several reasons:

N First, the NY99 strain, which the recent outbreaks involve, canbe amplified in a large number of avian species, and thus latent

amplifying and reservoir hosts could possibly inhabit theregion.

N Secondly, amplification of the WNV NY99 strain wasexperimentally demonstrated in jungle crows (Corvus macro-rhynchos), one of the major corvids in the area.

N Thirdly, WNV is transmitted by many species of mosquitoesand many potential WNV vector species inhabit the region.Thus, the introduction of WNV is a threat to public and animalhealth in East Asia.

In several areas of Japan and other East Asian countries, aigamoducks, a cross between wild and domestic ducks (Anas platyrhynchosand Anas platyrhynchos var. domesticus, respectively), are reared formeat production and for supporting wet-rice cultivation. For thelatter purpose, aigamo ducks are allowed to swim and/or walk inpaddy fields so that they can eat weeds and insects that harm the ricecrop. Wet-rice cultivation using aigamo ducks has been practiced asorganic agriculture. Although it is unknown whether or not aigamoducks are susceptible to WNV infection, it is conceivable that theyare susceptible in light of the fact that WNV outbreaks occurred at acommercial flock of domestic ducks in the United States and Canada;moreover, the susceptibility of mallards was revealed by experimentalinfection. Thus, there has been a concern that aigamo ducks mayspread WNV infection if the virus is introduced to East Asia.Copyright E 2009, American Association of Avian Pathologists, Inc. 1933-5334 online

Summarized from Avian Diseases, Vol. 53, No. 2, 2009, Pages 239–244

Fig. 1. Immunohistochemistry of the heart (Duck 10). Denatured myocardial cells containing WNV antigen are scattered in the heart. Bar 5 30 mm.Fig. 2. Immunohistochemistry of the kidney (Duck 10). WNV antigen is present in denatured tubular epithelial cells. Bar 5 30 mm.Fig. 3. Immunohistochemistry of the feather (Duck 10). Feather epithelial cells (panel A) and cells in feather pulp (panel B) show abundant presence of WNV

antigen. Bar 5 30 mm.

Experimental WNV infection in aigamo ducks