Multiple introductions of avian influenza viruses (H5N1), Laos, 2009-2010.
Avian influenza viruses (H5N1) of clades 188.8.131.52, 184.108.40.206, and 220.127.116.11 were introduced into Laos in 2009-2010.To investigate these viruses, we conducted active surveillance of poultry during March 2010.We detected viruses throughout Laos, including several interclade reassortants and 2 subgroups of clade 2.3.4, one of which caused an outbreak in May 2010.
Affiliation: Division of Virology, St Jude Children’s Research Hospital, Memphis, Tennessee 38105, USA. firstname.lastname@example.org
Avian influenza viruses (H5N1) of clades 18.104.22.168, 22.214.171.124, and 126.96.36.199 were introduced into Laos in 2009-2010. To investigate these viruses, we conducted active surveillance of poultry during March 2010. We detected viruses throughout Laos, including several interclade reassortants and 2 subgroups of clade 2.3.4, one of which caused an outbreak in May 2010.
- Disease Outbreaks*
- Influenza A Virus, H5N1 Subtype*/classification/genetics/isolation & purification
- Influenza in Birds/epidemiology*/virology
- Poultry Diseases/epidemiology*/virology
- Sentinel Surveillance/veterinary
- Sequence Analysis, DNA
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FA.1: Phylogenetic relationships of hemagglutinin 5 (H5) gene segments of avian influenza viruses (H5N1), Laos, 2009–2010. The tree was rooted in A/goose/Guangdong/1/1996 (nt 91–919, H5 numbering). Surveillance sequences are indicated in boldface and marked with black (isolates) or open (direct sequences) squares. Bootstrap values >75 are shown. Clade numbers are shown on the right. Scale bar indicates nucleotide substitutions per site. A/chicken/Laos/Xayathiani-32/2006-like, A/pigeon/Laos/P0022/2007-like, and A/chicken/Laos/LPQ001/2008-like viruses each represent 3 sequences with identical hemagglutinins. Reference viruses were obtained through EpiFlu of the Global Initiative on Sharing All Influenza Data and provided by the following laboratories in addition to sequences already in the public domain: A/chicken/Vietnam/NCVD-407/2010, A/chicken/Vietnam/NCVD-394/2010, A/chicken/Vietnam/NCVD-398/2010, A/chicken/Vietnam/NCVD-399/2010, A/duck/Vietnam/NCVD-422/2010, A/chicken/NCVD-404/2010, A/Muscovy_duck/Vietnam/NCVD-401/2010, A/chicken/Vietnam/NCVD-421/2010 A/duck/Vietnam/NCVD-423/2010 (original laboratory: National Centre of Veterinary Diagnostics, Hanoi, Vietnam; submitting laboratory: Centers for Disease Control and Prevention, Atlanta, GA, USA); A/Hunan/2/2009, A/Hunan/1/2009, A/Guizhou/1/2009, A/Guangxi/1/2009, A/environment/Guizhou/2/2009, A/environment/Guizhou/4/2009, A/environment/Guizhou/7/2009, A/environment/Guizhou/9/2009, A/water/Hunan/7/2009A/Guangxi/1/2008, A/Guangdong/1/2008, A/Hunan/1/2008, A/duck feces/Hebei/5/2009 (original and submitting laboratory: World Health Organization Chinese National Influenza Center, Beijing, China), Jiangsu/1-like–A/tree_sparrow/Jiangsu/1/2008–like viruses.
During March 2010, a total of 3,695 swab specimens were collected (1,928 duck and 279 chicken cloacal samples, 446 duck tracheal samples, 675 fecal samples, and 367 water samples). M gene prevalence was 4.0% (ducks), 1.8% (chickens), and 0.3% (environment samples). Five isolates were obtained (Figure A1). All M gene–positive swab specimens were collected in 13 locations (8 backyards, 2 markets, and 3 farms) (Table 1; Figure) Sample protection was suboptimal, and only 21 samples could be subtyped by real-time RT-PCR and sequencing (Table 1).