One of the most important avian migratory pathways in the world is the East Asian- Australasian Flyway (EAAF), which is described (below) by the EEAFP (East Asian-Australasian Flyway Partnership), which monitors the arrival and health of migratory birds along the route each year.
The East Asian - Australasian Flyway (EAAF) stretches from the Russian Far East and Alaska, southwards through East Asia and South-east Asia, to Australia and New Zealand and encompasses 22 countries. The EAAF is home to over 50 million migratory waterbirds from over 250 different populations, including 32 globally threatened species and 19 Near Threatened species.Although it has been the source of excitement and wonder for bird lovers every fall for uncounted eons, in recent years the annual southbound trek of migratory birds has also been associated with the arrival and spread of HPAI and LPAI viruses.
In 2015 - following North America's record HPAI H5 epizootic - we looked at a study (see PNAS: The Enigma Of Disappearing HPAI H5 In North American Migratory Waterfowl) which concluded that while migratory waterfowl can briefly carry HPAI H5, they were not a good long-term reservoir for highly pathogenic avian flu viruses.
HPAI viruses appeared to burn out fairly quickly in aquatic waterfowl populations - likely due to their immunity to LPAI viruses - and would therefore have to be reintroduced periodically.That seems to have changed somewhat when, in the fall of 2016, H5N8 returned to Europe after an 18-month absence and brought with it a number of genetic and behavioral changes attributed to a reassortment event that likely took place sometime in the spring of 2016 (see EID Journal: Reassorted HPAI H5N8 Clade 22.214.171.124. - Germany 2016).
Among the changes noted in this reassorted HPAI H5N8 virus was enhanced virulence in wild birds, an expanded avian host range, and perhaps most notably, unusual environmental persistence into the summer.This reassorted virus H5N8 also managed to make it into the Middle East, West Africa, and most remarkably - the Southern Hemisphere - where it continues to be reported today.
A another study, published in 2016 (see Sci Repts.: Southward Autumn Migration Of Waterfowl Facilitates Transmission Of HPAI H5N1), suggested that waterfowl pick up new HPAI viruses in the spring (likely from poultry or terrestrial birds) on their way to their summer breeding spots - where they spread and potentially evolve - and then redistribute them on their southbound journey the following fall.
Last fall, we saw a new strain of HPAI H5N6 show up in Japan, South Korea, Taiwan and 10,000km away in Northern Europe (The Netherlands) literally within days of each other, lending credence to this new theory (see EID Journal: Novel HPAI A(H5N6) Virus in the Netherlands, December 2017).Last year's HPAI H5N6 was far milder than the previous year's HPAI H5N8 - which sparked a record setting epizootic in Europe - but we won't know what (if anything) this year's migration will bring for a few more weeks.
South Korea, which serves as a stopping place and overwintering home for millions of migratory birds each year, has been particularly hard hit by H5N8 and H5N6 for the past 4 years, resulting in their poultry industry losing tens of millions of birds.While past performance is no guarantee of future results, and we've seen some years where avian flu was a no-show, today South Korea's Ministry of Agriculture (MAFRA) issued a warning that the first migratory birds of fall are starting to arrive, and that biosecurity must be enhanced going into the winter.
2018.10.02 15:34:48 Rural Policy Bureau
The Ministry of Agriculture, Forestry and Livestock Quarantine Headquarters (headquartered by Park Bong-gyun, hereinafter referred to as the 'quarantine headquarters') issued an alien warning for the arrival of birds in the poultry farms and municipalities to strengthen the anti- He said.
❍ In order to prevent the spread of AI between poultry and migratory birds using the new information of wintertime provided by the Ministry of Environment (National Biological Resource Center) provided by the Ministry of Environment, It is.* The information system of migratory birds is divided into 4 stages
In response to the announcement of the arrival of the migratory birds, the quarantine headquarters issued strict prevention measures against poultry farmers and local governments.
❍ (Poultry farmers) Exercise control of entrance and exit of migratory birds, maintenance of inside and outside walls of houses, installation of exclusive clothing and shoes when entering the house, installation of disinfection basin and periodical replacement of disinfection water
❍ (Local government) Strengthening of publicity including installation and operation of disinfection facilities in the migration route between migratory bird communities and poultry farms, prevention of migration of migratory birds,
The quarantine headquarters will continue to monitor the migration status of migratory birds in cooperation with the Ministry of Environment and provide information on the status of migratory birds to farmers.
❍ For reference, to prevent the influx of birds into the country, the period from October 1 to February next year will be designated as the period of special avian influenza pandemic, and the establishment of 24 hour emergency contact network, strengthening of border inspection, And plans for prevention, such as guidance and inspection plans.
While we generally see our first fall avian flu outbreaks reported from somewhere in East Asia (South Korea or Japan), followed then by Eastern or Northern Europe - and more rarely North America - the chief lesson of the past few years is that avian flu often zigs when we expect it to zag.
The appearance of a new H5N2 reassortant virus in Russia last winter, and again this summer, is obviously a concern, as are whatever new evolutionary changes that may have occurred with other H5 subtypes.But the truth is - like with seasonal flu - we won't know what kind of avian flu season we're going to see until its over.
A good enough reason that all poultry interests in the Northern Hemisphere should take heed of the season and beef up their biosecurity now, and not wait to see what this fall brings.