Giuseppe
Emeritus
Influenza A Virus Infections in Land Birds, People’s Republic of China
A. Townsend Peterson, Sarah E. Bush, Erica Spackman, David E. Swayne, and Hon S. Ip - Author affiliations: University of Kansas, Lawrence, Kansas, USA (A.T. Peterson, S.E. Bush); US Department of Agriculture, Athens, Georgia, USA (E. Spackman, D.E. Swayne); and US Geological Survey, Madison, Wisconsin, USA (H.S. Ip)
Water birds are considered the reservoir for avian influenza viruses.
We examined this assumption by sampling and real-time reverse transcription–PCR testing of 939 Asian land birds of 153 species.
Influenza A infection was found, particularly among migratory species.
Surveillance programs for monitoring spread of these viruses need to be redesigned.
(...)
Conclusions
The subtype H5N1 strain of influenza virus has spread rapidly and has been detected across much of central and southern Eurasia.
Although movements of wild birds have been implicated in this spread (8), other studies question (9,10) or contradict (11) this idea.
An important part of the argument centers on the question of the occurrence of the virus in wild birds without obvious illness, which can be difficult to interpret given the low prevalence of influenza.
For instance, a recent study based on sampling >13,000 migratory birds in China detected the subtype H5N1 strain of influenza virus only 8 times (12), and similar results have been obtained elsewhere (2).
Our study, although not successful in characterizing influenza viruses to specific strains, nonetheless shows that influenza A virus infection occurs in more bird species than previously assumed and that influenza A infections can be found in birds that behave normally and show no sign of illness.
Although a review of avian influenza virus ecology (1) discussed the occurrence of influenza viruses across all groups of birds (and other vertebrates), subsequent studies have assumed that waterbirds are the primary reservoir (8,13,14).
In this study, a broad sample of land birds yielded frequent influenza-positive results.
Although waterbirds could have higher prevalences, we have demonstrated broad occurrence of influenza viruses in diverse taxa of Passeriformes (songbirds) in Southeast Asia. This result suggests that land birds may also be a major reservoir of influenza viruses.
We have taken a step toward a more complete understanding of influenza virus ecology among wild birds. Our partial survey of influenza virus distributions across the rich avifaunas of the southern region of China demonstrated frequent infections. This result contrasts with the current dogma in the influenza surveillance community. We suggest that to be effective future surveillance efforts will need to include the full diversity of wild birds. (...)
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http://www.cdc.gov/eid/content/14/10/pdfs/08-0169.pdf
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A. Townsend Peterson, Sarah E. Bush, Erica Spackman, David E. Swayne, and Hon S. Ip - Author affiliations: University of Kansas, Lawrence, Kansas, USA (A.T. Peterson, S.E. Bush); US Department of Agriculture, Athens, Georgia, USA (E. Spackman, D.E. Swayne); and US Geological Survey, Madison, Wisconsin, USA (H.S. Ip)
Water birds are considered the reservoir for avian influenza viruses.
We examined this assumption by sampling and real-time reverse transcription–PCR testing of 939 Asian land birds of 153 species.
Influenza A infection was found, particularly among migratory species.
Surveillance programs for monitoring spread of these viruses need to be redesigned.
(...)
Conclusions
The subtype H5N1 strain of influenza virus has spread rapidly and has been detected across much of central and southern Eurasia.
Although movements of wild birds have been implicated in this spread (8), other studies question (9,10) or contradict (11) this idea.
An important part of the argument centers on the question of the occurrence of the virus in wild birds without obvious illness, which can be difficult to interpret given the low prevalence of influenza.
For instance, a recent study based on sampling >13,000 migratory birds in China detected the subtype H5N1 strain of influenza virus only 8 times (12), and similar results have been obtained elsewhere (2).
Our study, although not successful in characterizing influenza viruses to specific strains, nonetheless shows that influenza A virus infection occurs in more bird species than previously assumed and that influenza A infections can be found in birds that behave normally and show no sign of illness.
Although a review of avian influenza virus ecology (1) discussed the occurrence of influenza viruses across all groups of birds (and other vertebrates), subsequent studies have assumed that waterbirds are the primary reservoir (8,13,14).
In this study, a broad sample of land birds yielded frequent influenza-positive results.
Although waterbirds could have higher prevalences, we have demonstrated broad occurrence of influenza viruses in diverse taxa of Passeriformes (songbirds) in Southeast Asia. This result suggests that land birds may also be a major reservoir of influenza viruses.
We have taken a step toward a more complete understanding of influenza virus ecology among wild birds. Our partial survey of influenza virus distributions across the rich avifaunas of the southern region of China demonstrated frequent infections. This result contrasts with the current dogma in the influenza surveillance community. We suggest that to be effective future surveillance efforts will need to include the full diversity of wild birds. (...)
-
http://www.cdc.gov/eid/content/14/10/pdfs/08-0169.pdf
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