Outbreaks of highly pathogenic avian influenza   H5N1 clade 2.3.2.1c in hunting falcons and   kept wild birds in Dubai implicate intercontinental   virus spread.
Highly pathogenic avian influenza viruses (HPAIVs) of subtype H5N1 have continued to perpetuate with divergent genetic variants in poultry within Asia since 2003. Further dissemination of Asian-derived H5 HPAIVs to Europe, Africa and, most recently, to the North American continent has occurred. We report an outbreak of HPAIV H5N1 among falcons kept for hunting and other wild bird species bred as falcon prey in Dubai, United Arab Emirates, during the autumn of 2014. The causative agent was identified as avian influenza virus subtype H5N1, clade 2.3.2.1c, by genetic and phylogenetic analyses. High mortality in infected birds was in accordance with systemic pathomorphological and histological alterations in affected falcons. Genetic analysis showed the HPAIV H5N1 of clade 2.3.2.1c is a reassortant in which the PB2 segment was derived from an Asian-origin H9N2 virus lineage. The Dubai H5N1 viruses were closely related to contemporary H5N1 HPAIVs from Nigeria, Burkina-Faso, Romania and Bulgaria. Median-joining network analysis of 2.3.2.1c viruses revealed that the Dubai outbreak was an episode of a westward spread of these viruses on a larger scale from unidentified Asian sources. The incursion into Dubai, possibly via infected captive hunting falcons returning from hunting trips to central Asian countries, preceded outbreaks in Nigeria and other West African countries. The alarmingly enhanced geographical mobility of clade 2.3.2.1.c and clade 2.3.4.4 viruses may represent another wave of transcontinental dissemination of Asian-origin HPAIV H5 viruses, such as the outbreak at Qinghai Lake caused by clade 2.2 (‘Qinghai’ lineage) in 2005.
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald Insel-Riems, Germany.
Mahmoud M
MM
Naguib
Central Veterinary Research Laboratory, P.O. Box 597, Dubai, United Arab Emirates.
Jörg
J
Kinne
Department of Microbiology, University of Hong Kong, Hong Kong, China.
Honglin
H
Chen
Department of Microbiology, University of Hong Kong, Hong Kong, China.
Kwok-Hung
KH
Chan
Central Veterinary Research Laboratory, P.O. Box 597, Dubai, United Arab Emirates.
Sunitha
S
Joseph
Department of Microbiology, University of Hong Kong, Hong Kong, China.
Po-Chun
PC
Wong
Department of Microbiology, University of Hong Kong, Hong Kong, China.
Patrick C Y
PCY
Woo
Central Veterinary Research Laboratory, P.O. Box 597, Dubai, United Arab Emirates.
Renate
R
Wernery
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald Insel-Riems, Germany.
Martin
M
Beer
Central Veterinary Research Laboratory, P.O. Box 597, Dubai, United Arab Emirates.
Ulrich
U
Wernery
Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald Insel-Riems, Germany.
Timm C
TC
Harder
D000818:Animals; D000835:Animals, Wild / Q000821:virology; D046093:Falconiformes / Q000821:virology*; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D005585:Influenza in Birds / Q000453:epidemiology / Q000821:virology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D014479:United Arab Emirates / Q000453:epidemiology