A ‘high pathogenic’ type of bird flu was confirmed in an Otago egg farm over the weekend.
The Ministry for Primary Industries has confirmed the virus is not the H5N1 strain that has been causing deaths in poultry, wild birds, and mammals worldwide.
This outbreak may have originated from a less deadly type of bird flu that is found in New Zealand waterfowls, and mutated into a ‘high pathogenic’ strain while spreading between chickens.
The Science Media Centre asked experts to comment.
Professor Jemma Geoghegan, Virologist, University of Otago, comments:
“The detection of H7N6 at a New Zealand farm is worrying, however it is not the H5N1 strain that we are most worried about.
“Usually the H7 subtype is low pathogenic and is found in wild birds without causing disease. On some rare occasions, these viruses can spillover to poultry and evolve to become high pathogenic where they cause severe disease. This is what we saw happen in Australia a few months ago too. With chicken farms in such close proximity to wildlife, these sorts of spillovers are always a risk.
“The H7 subtype, while it has infected humans before, doesn’t spread very easily between them so this is low risk for public health.”
No conflicts of interest declared.
Nigel French, Distinguished Professor of Infectious Disease Epidemiology and Public Health, Massey University, comments:
“While there is a strong focus on early detection of the globally circulating ‘panzootic’ H5N1 strain of bird flu, MPI and infectious disease experts in Aotearoa have always been aware of the possibility of a local ‘conversion event’.
“Rather than importation through migratory wild birds, this is where a low pathogenic strain (LPAI) can develop into a high pathogenic strain (HPAI), locally, in a flock infected with the low pathogenic strain. LPAI strains are known to circulate in NZ wildlife, so this was always a possibility that needed to be prepared for.
“Such an event happened in Victoria, Australia earlier this year – that was a strain of H7N3 that most likely entered the flock through wildlife. This detection was followed by further detections of other strains of HPAI in other states, all most likely local conversion events.
“If the affected farm has been detected early there is a good chance this outbreak will be contained. However, vigilance and raised awareness for avian influenza is needed, whether it is for the globally circulating H5N1 strain, or locally evolved strain.
“The key message from MPI for the public is: “If anyone sees 3 or more sick or dead wild birds in a group, report it immediately to the exotic pest and disease hotline on 0800 80 99 66”.”
No conflicts of interest declared.