Type of bird flu virus found in NZ wild ducks

Wild mallard ducks in New Zealand have tested positive for a "low pathogenic" form of bird flu.

The virus, known as LPAI H5N, is closely related to viruses found in the past and has been here for some time, Ministry of Agriculture and Forestry (MAF) biosecurity staff said.

It is different to high pathogenic (HPAI) form of the bird flu virus. MAF official Andre van Halderen said that strains avian influenza viruses which did not cause disease were present in wild bird populations, and the find was "not unexpected".

Sampling of healthy wild birds took place at seven locations across New Zealand in February as part of avian influenza surveillance. A total of 1241 samples were collected from mostly mallard ducks and some migratory bird species in Paparoa, the mouth of Kaituna River, Lake Aniwhenua, Reparoa, Napier, Temuka and Invercargill.

"The risk of HPAI "bird flu" reaching New Zealand is unchanged and remains low," Dr van Halderen said.

Avian influenza viruses are naturally present in many species of wild birds, especially water fowl such as ducks and geeseand shorebirds, including migratory waders.

HPAI virus causes severe disease that spreads quickly, causing sudden death in birds, but LPAI viruses may cause mild illness or no clinical disease in birds.

Since 1975 over 5000 samples have been taken from wild birds in New Zealand. A small number of low pathogenic avian influenza viruses, including those of the H5 or H7 subtype, have been found in healthy mallard ducks. New Zealand has never had a case of HPAI.