Low pathogenic virus no cause for concern

A surveillance programme researching the presence of avian influenza in New Zealand has found low pathogenic (LPAI) H5N1 virus in two samples taken from mallard ducks. Tests indicate that the virus is closely related to viruses found in the past and has been here for some time.

LPAI H5N1 is different to ‘bird flu’, which is the high pathogenic (HPAI) form of the virus. The samples were taken from healthy birds and there have been no reported bird deaths or disease in the area since the samples were collected, says Team Manager, Animal Response, Dr Andre van Halderen.

“This confirms what we already know - that strains of non disease causing avian influenza viruses are present in our wild bird populations and when we increase surveillance we will find evidence of virus elsewhere. The finding of low pathogenic H5N1 is not unexpected.”

Sampling of healthy wild birds took place at seven locations across New Zealand in February this year, as part of MAFBNZ’s ongoing avian influenza surveillance programme. 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. This finding does not affect New Zealand's avian influenza disease free status, and poultry consumers have no cause for concern, Dr van Halderen said.”

Avian influenza viruses are naturally present in many species of wild birds, especially water fowl (ducks and geese) and shorebirds. Strains of avian influenza are categorised as highly pathogenic (HPAI) or low pathogenic (LPAI) on the basis of their ability to produce disease in poultry. HPAI causes severe disease that spreads quickly, causing sudden death in birds. LPAI viruses, depending on the strain, may cause mild or no clinical disease in birds. Most avian influenza viruses are harmless to humans.

In 2006 MAF Biosecurity New Zealand (MAFBNZ) increased surveillance for avian influenza to meet new World Organisation for Animal Health (OIE) reporting requirements and demonstrate New Zealand’s freedom from highly pathogenic avian influenza. The surveillance programme incorporates surveillance of poultry, resident and migratory wild birds.
Phase one of the programme sampled commercial broiler and layer farms throughout New Zealand in 2006. No notifiable avian influenza virus was found. These results again highlight the New Zealand poultry industry’s major disease-free status and strict farm biosecurity.

New Zealand has undertaken surveillance in wild birds, including migratory shorebirds & waders, local waterfowl and other species, since 1975. Over 5000 samples have been taken from wild birds (migrating and resident species) 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.

More information on avian influenza, including eight simple biosecurity tips to keep birds safe and healthy, can be found at:http://www.biosecurity.govt.nz/pest-and-disease-response/pests-and-diseases-watchlist/bird-flu

To report an exotic pest or disease call the MAF Biosecurity hotline on 0800 80 99 66.