Victoria State - Credit Wikipedia
#15,438
Not quite a month ago, Victoria agricultural officials announced the detection of a highly pathogenic (HPAI) H7N7 virus at an egg farm in Lethbridge, Victoria. A week later, a second outbreak was reported at a nearby farm(see Australia: 2nd Victoria Farm Hit By HPAI H7N7).This was the first outbreak of H7N7 in reported Australia since 2014.
While sporadic bird-to-human transmissions of H7N7 have been reported, it is not considered nearly as dangerous as either H5Nx or H7N9, as it usually produces only mild symptoms in humans.
Two notable outbreaks include:
- 3 mild cases were reported in Italy in 2013 (see ECDC Update & Assessment: Human Infection By Avian H7N7 In Italy).
- An in 2003 a large outbreak of H7N7 (89 confirmed, 1 fatality) was reported in the Netherlands – with nearly all reported cases having very mild (often just conjunctivitis) symptoms.
Less than a week later, a second avian flu subtype (LPAI H5N2) was reported at a Turkey farm (see OIE Report), in Bairnsdale, Victoria. This particular ubtype had not been reported by Australia since 2013.
As a general rule, LPAI (low path) viruses are of less concern than HPAI viruses. But LPAI H5 and H7 viruses both have the ability to mutate into highly pathogenic strains if allowed to circulate in poultry. Therefore all H5 and H7 viruses - regardless of pathogenicity - are reportable to the OIE.
Today, Victoria Agricultural officials are reporting that a 3rd subtype - LPAI H7N6 - has been detected at an emu farm in Kerang, Victoria along with a 3rd outbreak of HPAI H7N7. Once again, H7N6 is a subtype that hasn't been reported in Australia since 2013.
Australia's recent reports are mirrored by recent reports out of Russia of HPAI H5N8 in Chelyabinsk Oblast, Russia and HPAI H5Nx in Omsk Oblast, HPAI H5N6 in the Philippines, HPAI H5N1 in Vietnam, HPAI H5N5 in Taiwan, and the following report today from South Korea on their first detection of environmental (wild bird feces) avian influenza since March.
Detection of H7 type low pathogenic avian influenza antigen in wild bird feces in Seocho(Yangjaecheon), Gyeonggi (Gyeongancheon), Seoul2020.08.26 13:33:31 Defense Policy Bureau
The Ministry of Agriculture, Food and Rural Affairs (Minister Kim Hyeon-su) said,'Avian influenza test results for wild bird feces collected from Yongin (Gyeongancheon), Gyeonggi-do on August 18th and Seocho-gu, Seoul (Yangjaecheon) on August 20th. Avian influenza (AI) was detected.
❍ This is the first time that an avian influenza antigen has been detected in this wild bird since March 18, Gangneung, Gangwon-do (Namdaecheon, H5N3 type low pathogenicity).
Accordingly, the Ministry of Agriculture and Food has implemented emergency quarantine measures* in accordance with the Avian Influenza Emergency Action Guidelines (AI SOP), and although it has been identified as a low pathogenic avian influenza, quarantine measures such as continuous disinfection measures are maintained for 7 days.
While none of these reports is particularly alarming, we do seem to be seeing a surge in avian flu activity after nearly 3 years of relative quiescence. Globally, since China rolled out their experimental H5+H7 poultry vaccination campaign in the summer of 2017, we've seen a remarkable drop in outbreaks.
But the news hasn't been all good. We've seen some subtle signs that avian flu may be staging a bit of a comeback, as reported previously in:
The twice annual (fall and spring) migration of birds is about to begin, and in the northern hemisphere that means that billions of birds will soon leave their high latitude roosting spots and begin to head south for the winter.
As described in a study published in 2016 (see Sci Repts.: Southward Autumn Migration Of Waterfowl Facilitates Transmission Of HPAI H5N1), the evidence suggests 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.
Which means that once again this fall, the risks of seeing new outbreak of avian flu - and potentially new subtypes - will increase (see WHO: Migratory Birds & The Potential Spread Of Avian Influenza), and poultry interests across the Northern Hemisphere will need to be extra vigilant with their bio-security if we are to avoid another avian epizootic like we saw in North America in 2015, and Europe in 2016-17.
