China MOA Announces 3rd Wild Bird Die-Off From HPAI H5N8 In A Month

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For the 7th time in 2021, and for the 3rd time in a month, China's MOA has announced an avian influenza outbreak and wild-bird die-off due to HPAI H5N8.  While susceptible to HPAI viruses - unlike poultry, which tend to have a high fatality rate - wild birds are generally able to tolerate the infection.

That is, unless the virus is somehow different from ones they are used to. 

Over the past two decades, wild bird die-offs have often signaled the emergence of new clades of HPAI H5 viruses, and those that have occured during the summer in China and Russia have sometimes served as harbingers of what would arrive the following fall in Europe. 

  A few (of many) examples.

• In May of 2005 the first major expansion of H5N1 beyond Southeast Asia began when suddenly and unexpectedly, waterfowl (brown headed gulls, cormorants, ducks, geese, etc.) died en mass at Qinghai Lake, China- and quickly spread via migratory birds into Europe, Africa, and the Middle east signaling the emergence of clade 2.2 (aka QH05) of the H5N1 virus.

• In 2009 researchers found evidence of another emerging clade - (2.3.2) - (see 2011 EID Journal New Avian Influenza Virus (H5N1) in Wild Birds, Qinghai, China), at Qinghai lake. In short order this emerging 2.3.2 clade began to show up in migratory birds, and poultry, from Japan to India, supplanting the old 2.2 clade in many regions.

• In January of 2015 we saw another `Qinghai-like' die off of birds, this time in Henan Province, China which was subsequently identified as clade 2.3.2.1c (see Novel H5N1 Reassortment Detected In Migratory Birds - China). Within months this new sub clade was seen in Nigeria.

• In June of 2016, in OIE: Russia - HPAI H5 In Wild & Migratory Birds, we saw a report of a number of birds taken by hunters earlier that month in and around Ubsu-Nur Lake in Russia that had tested positive for HPAI H5. Three months later it was confirmed by FAO/EMPRES to be H5N8 Clade 2.3.4.4., which by November of 2016 had sparked Europe's largest avian epizootic on record.

• Over the summer of 2020, Russia reported die offs of wild birds, and outbreaks in poultry, due to HPAI H5N8.  Last fall Europe began its second largest avian epizootic on record.

While HPAI H5N8 has mainly been a threat to poultry and (more recently) wild birds since it emerged in 2014, earlier this year Russia reported the 1st confirmed human infections with HPAI H5N8. 

Although the risk of human infection appears to be very low, in March the WHO called for the development of a Candidate Vaccine Virus (CVV) against avian H5N8 (see WHO: Candidate Vaccine Viruses for Pandemic Preparedness - March 2021), and in May the CDC Added Zoonotic Avian A/H5N8 To Their IRAT List.

We've also looked at two cautionary studies from Chinese scientists over the past six weeks, both of which have warned on the emergence and spread of an ever-evolving HPAI H5N8 virus in China.

Last month, in  Science: Emerging H5N8 Avian Influenza Viruses, we looked at a review by two well-respected Chinese scientists (Weifeng Shi and George F. Gao)  on the evolution, and growing zoonotic threat, of avian H5N8, stating:

•  the  ". . . global spread of AIVs, particularly the H5N8 subtype, has become a major concern to poultry farming and wildlife security but, critically, also to global public health."
• And due to the ". . . long-distance migration of wild birds, the innate capacity for reassortment of AIVs, the increased human-type receptor binding capability, and the constant antigenic variation of HPAIVs  the authors warned that it was imperative that " . . . the global spread and potential risk of H5N8 AIVs to poultry farming, avian wildlife, and global public health are not ignored."

And less than a week ago, in V. Evolution: Genomic Evolution, Transmission Dynamics, and Pathogenicity of Avian H5N8 Viruses Emerging in China, 2020, we saw Chinese researchers describe the rapid rise in 2020 of an antigenically distinct H5N8 virus that is lethal to chickens and mice, that is similar to the Russian Zoonotic strain, and has shown signs of mammalian adaptation.

All of which makes this third report out of China in the last month worth noting. 

A wild bird H5N8 subtype highly pathogenic avian influenza outbreak occurred in the Nanhu area at the junction of Lingwu City and Yanchi County in Ningxia

Release time: 2021-06-20
Source: Information Office of the Ministry of Agriculture and Rural Affairs 

The Information Office of the Ministry of Agriculture and Rural Affairs announced on June 20 that a wild bird H5N8 subtype highly pathogenic avian influenza epidemic occurred in the Nanhu area at the junction of Lingwu City and Yanchi County in Ningxia Hui Autonomous Region.

On June 20, the Ministry of Agriculture and Rural Affairs received a report from the China Animal Disease Prevention and Control Center, which was confirmed by the National Avian Influenza Reference Laboratory at the junction of Majiatan Town, Lingwu City, Ningdong Development Zone, Yinchuan City, and Fengjigou Township, Yanchi County, Wuzhong City An outbreak of highly pathogenic avian influenza of wild fowl H5N8 subtype occurred in the South Lake area of ​​China. 38 wild poultry died in the epidemic site.

After the outbreak, the local area immediately activated an emergency response mechanism, carried out emergency response work, treated all sick and dead wild birds in a harmless manner, and disinfected the surrounding environment.

Since the beginning of this year, a total of 7 highly pathogenic avian influenza outbreaks (all wild birds) have been reported across the country.

It is also worth noting that following nearly 3 relatively quiet years - from mid-2017 to early 2020 - avian influenza activity in China - and around the globe - has been rising, with HPAI H5 viruses and LPAI H9N2 leading the way.  

China has reported 6 H5N6 human infections since December, more than a dozen mild H9N2 infections, and at least 1 H10N3 infection.  In addition Laos has reported both a human H5N1 and a human H5N6 infection since last fall. 

Given the lack of influenza surveillance and reporting from many parts of the world, it is likely that additional cases go unreported.  While we aren't anywhere near the levels of avian flu human infections we we're seeing between 2003 and 2016, the recent uptick is worth our attention. 

As are increased reports of wild bird die offs due to HPAI H5N8.