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Wild ducks as long-distance vectors of highly pathogenic avian influenza virus (H5N1).

Keawcharoen J, van Riel D, van Amerongen G, Bestebroer T, Beyer WE, van Lavieren R, Osterhaus AD, Fouchier RA, Kuiken T - Emerging Infect. Dis. (2008)

Bottom Line: Wild birds have been implicated in the expansion of highly pathogenic avian influenza virus (H5N1) outbreaks across Asia, the Middle East, Europe, and Africa (in addition to traditional transmission by infected poultry, contaminated equipment, and people).By experimentally infecting wild ducks, we found that tufted ducks, Eurasian pochards, and mallards excreted significantly more virus than common teals, Eurasian wigeons, and gadwalls; yet only tufted ducks and, to a lesser degree, pochards became ill or died.These findings suggest that some wild duck species, particularly mallards, can potentially be long-distance vectors of highly pathogenic avian influenza virus (H5N1) and that others, particularly tufted ducks, are more likely to act as sentinels.

View Article: PubMed Central - PubMed

Affiliation: Erasmus Medical Center, Rotterdam, the Netherlands.

ABSTRACT
Wild birds have been implicated in the expansion of highly pathogenic avian influenza virus (H5N1) outbreaks across Asia, the Middle East, Europe, and Africa (in addition to traditional transmission by infected poultry, contaminated equipment, and people). Such a role would require wild birds to excrete virus in the absence of debilitating disease. By experimentally infecting wild ducks, we found that tufted ducks, Eurasian pochards, and mallards excreted significantly more virus than common teals, Eurasian wigeons, and gadwalls; yet only tufted ducks and, to a lesser degree, pochards became ill or died. These findings suggest that some wild duck species, particularly mallards, can potentially be long-distance vectors of highly pathogenic avian influenza virus (H5N1) and that others, particularly tufted ducks, are more likely to act as sentinels.

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Central nervous system changes in wild ducks experimentally infected with highly pathogenic avian influenza virus (H5N1). A) Torticollis in a pochard. B) Severe multifocal encephalitis, characterized by abundant influenza virus antigen expression in neurons and glial cells and C) extensive necrosis and inflammation, in a tufted duck. D) Rare virus antigen expression in neurons and E) mild necrosis and inflammation in a gadwall that did not show neurologic signs and had only mild focal encephalitis. F) Lack of virus antigen expression and G) lack of necrosis and inflammation in brain tissue of a mallard that did not show neurologic signs. Tissues were stained either by immunohistochemistry that used a monoclonal antibody against the nucleoprotein of influenza A virus as a primary antibody (B, D, F) or with hematoxylin and eosin (C, E, G); original magnification ×100.
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Figure 1: Central nervous system changes in wild ducks experimentally infected with highly pathogenic avian influenza virus (H5N1). A) Torticollis in a pochard. B) Severe multifocal encephalitis, characterized by abundant influenza virus antigen expression in neurons and glial cells and C) extensive necrosis and inflammation, in a tufted duck. D) Rare virus antigen expression in neurons and E) mild necrosis and inflammation in a gadwall that did not show neurologic signs and had only mild focal encephalitis. F) Lack of virus antigen expression and G) lack of necrosis and inflammation in brain tissue of a mallard that did not show neurologic signs. Tissues were stained either by immunohistochemistry that used a monoclonal antibody against the nucleoprotein of influenza A virus as a primary antibody (B, D, F) or with hematoxylin and eosin (C, E, G); original magnification ×100.

Mentions: Despite the low doses of virus used to inoculate the ducks, rates of productive infection in the 6 species were high: 76% according to virus isolation and 93% according to RT-PCR (Table). HPAIV (H5N1) infection caused clinical signs of disease in only tufted ducks and pochards, both of which are diving ducks in the genus Aythya (Table). In contrast, the remaining 4 species—all dabbling ducks belonging to the genus Anas—were clinically unaffected. Clinical signs, which were more severe in tufted ducks than in pochards, developed at 3 to 4 dpi and consisted of labored breathing, increased recumbency, and neurologic signs (torticollis [Figure 1, panel A], circling, loss of balance, and head tremors). Severely affected birds died or were euthanized in a moribund state at 4 dpi. Mildly affected birds recovered by 7 or 8 dpi.


Wild ducks as long-distance vectors of highly pathogenic avian influenza virus (H5N1).

Keawcharoen J, van Riel D, van Amerongen G, Bestebroer T, Beyer WE, van Lavieren R, Osterhaus AD, Fouchier RA, Kuiken T - Emerging Infect. Dis. (2008)

Central nervous system changes in wild ducks experimentally infected with highly pathogenic avian influenza virus (H5N1). A) Torticollis in a pochard. B) Severe multifocal encephalitis, characterized by abundant influenza virus antigen expression in neurons and glial cells and C) extensive necrosis and inflammation, in a tufted duck. D) Rare virus antigen expression in neurons and E) mild necrosis and inflammation in a gadwall that did not show neurologic signs and had only mild focal encephalitis. F) Lack of virus antigen expression and G) lack of necrosis and inflammation in brain tissue of a mallard that did not show neurologic signs. Tissues were stained either by immunohistochemistry that used a monoclonal antibody against the nucleoprotein of influenza A virus as a primary antibody (B, D, F) or with hematoxylin and eosin (C, E, G); original magnification ×100.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2570914&req=5

Figure 1: Central nervous system changes in wild ducks experimentally infected with highly pathogenic avian influenza virus (H5N1). A) Torticollis in a pochard. B) Severe multifocal encephalitis, characterized by abundant influenza virus antigen expression in neurons and glial cells and C) extensive necrosis and inflammation, in a tufted duck. D) Rare virus antigen expression in neurons and E) mild necrosis and inflammation in a gadwall that did not show neurologic signs and had only mild focal encephalitis. F) Lack of virus antigen expression and G) lack of necrosis and inflammation in brain tissue of a mallard that did not show neurologic signs. Tissues were stained either by immunohistochemistry that used a monoclonal antibody against the nucleoprotein of influenza A virus as a primary antibody (B, D, F) or with hematoxylin and eosin (C, E, G); original magnification ×100.
Mentions: Despite the low doses of virus used to inoculate the ducks, rates of productive infection in the 6 species were high: 76% according to virus isolation and 93% according to RT-PCR (Table). HPAIV (H5N1) infection caused clinical signs of disease in only tufted ducks and pochards, both of which are diving ducks in the genus Aythya (Table). In contrast, the remaining 4 species—all dabbling ducks belonging to the genus Anas—were clinically unaffected. Clinical signs, which were more severe in tufted ducks than in pochards, developed at 3 to 4 dpi and consisted of labored breathing, increased recumbency, and neurologic signs (torticollis [Figure 1, panel A], circling, loss of balance, and head tremors). Severely affected birds died or were euthanized in a moribund state at 4 dpi. Mildly affected birds recovered by 7 or 8 dpi.

Bottom Line: Wild birds have been implicated in the expansion of highly pathogenic avian influenza virus (H5N1) outbreaks across Asia, the Middle East, Europe, and Africa (in addition to traditional transmission by infected poultry, contaminated equipment, and people).By experimentally infecting wild ducks, we found that tufted ducks, Eurasian pochards, and mallards excreted significantly more virus than common teals, Eurasian wigeons, and gadwalls; yet only tufted ducks and, to a lesser degree, pochards became ill or died.These findings suggest that some wild duck species, particularly mallards, can potentially be long-distance vectors of highly pathogenic avian influenza virus (H5N1) and that others, particularly tufted ducks, are more likely to act as sentinels.

View Article: PubMed Central - PubMed

Affiliation: Erasmus Medical Center, Rotterdam, the Netherlands.

ABSTRACT
Wild birds have been implicated in the expansion of highly pathogenic avian influenza virus (H5N1) outbreaks across Asia, the Middle East, Europe, and Africa (in addition to traditional transmission by infected poultry, contaminated equipment, and people). Such a role would require wild birds to excrete virus in the absence of debilitating disease. By experimentally infecting wild ducks, we found that tufted ducks, Eurasian pochards, and mallards excreted significantly more virus than common teals, Eurasian wigeons, and gadwalls; yet only tufted ducks and, to a lesser degree, pochards became ill or died. These findings suggest that some wild duck species, particularly mallards, can potentially be long-distance vectors of highly pathogenic avian influenza virus (H5N1) and that others, particularly tufted ducks, are more likely to act as sentinels.

Show MeSH
Related in: MedlinePlus