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Frequently Asked Questions - Avian Influenza
Avian influenza is a disease of birds. There are many strains of avian influenza viruses, which are naturally present in many species of healthy wild birds, especially water fowl (ducks and geese). Most strains of avian influenza virus do not cause disease in humans or birds, and are not of human health concern.
Strains of avian influenza can be categorised as highly pathogenic (HPAI) or of low pathogenicity (LPAI) on the basis of the severity of clinical signs in chickens. LPAI viruses may cause mild or no clinical disease in chickens, but are of no concern to human health. Certain strains of LPAI virus of the H5 and H7 subtype have changed to become highly pathogenic avian influenza (HPAI). The evolution of LPAI virus into a highly pathogenic disease in birds is rare.
What is highly pathogenic avian influenza?
Highly pathogenic avian influenza is a highly contagious viral infection that can affect all species of birds. The viruses that cause avian influenza are Influenza A viruses of the family Orthomyxoviridae. Avian influenza viruses are present worldwide, and numerous ‘subtypes’ and ‘strains’ exist.
Highly pathogenic subtypes arise by re-assortment and recombination of the genetic material between different strains. Although not all H5 or H7 subtypes cause disease, all overseas outbreaks of highly pathogenic avian influenza (HPNAI) to date have been H5 and H7. This has prompted the World Organisation for Animal Health (OIE) to designate H5 and H7 as notifiable avian influenza (NAI) because of their potential pathogenicity. This means these subtypes must be reported to the OIE when found in poultry, regardless of whether they are highly pathogenic (HPNAI) or of low pathogenicity (LPNAI).
What strain of avian influenza is the current global outbreak?
The current outbreak is caused by strains of the H5N1 subtype of highly pathogenic avian influenza (HPNAI) virus which has caused significant disease in South East Asian poultry since 2003. The spread of H5N1 (bird flu) from SE Asia across Russia to Europe and Africa is a concern because of the number of countries affected at the same time, the level of human exposure due to the size of the outbreaks, and the wider range of birds including wild ducks, swans, geese and also mammals affected.
Why do only some strains of avian influenza cause disease in birds?
The majority of avian influenza viruses cause no disease in their natural hosts. Some H5 or H7 viruses cause a much milder disease (low pathogenic avian influenza, LPAI), where signs of sickness are much less evident or even absent and far fewer birds die.
It is not known why some strains of avian influenza become highly infectious in some species under certain circumstances while others do not, but it is thought that inter-species mixing (i.e. quails, geese, ducks and chickens) and high bird population densities, such as those that occur in bird markets in China and other Asian countries, may promote interspecies transmission and subsequent re-assortment of the viruses. New Zealand does not have these situations.
Are there avian influenza viruses in New Zealand?
About 3500 samples have been taken from wild birds in New Zealand since 1976. Only three low pathogenic notifiable avian influenza viruses (LPNAI) have been found (one H7 and two H5). All viruses have been found in mallard ducks, and all are harmless to birds and humans.
Could migratory birds import avian influenza virus to New Zealand?
Migratory waterfowl (ducks and geese) present a natural reservoir for avian viruses and can be responsible for the primary introduction of infection in other countries. Fortunately, New Zealand is not on a migration pathway of any waterfowl, except very occasionally vagrants from southern Australia. Wild birds are considered to be a very low risk to New Zealand.
In New Zealand, the majority of migratory birds are shorebirds or waders, including bar-tailed godwit, lesser knot, ruddy turnstone, Pacific golden plover that arrive from Siberian breeding grounds in September-October. There is evidence that some fly directly to New Zealand but others stop off in Asia and Australia. Shorebirds present a much lower risk than waterfowl (geese/ducks) because they shed less virus and mix less with poultry.
Has MAF checked migratory birds and waterfowl?
MAF has long been aware of the theoretical risk of introduction of avian influenza viruses by migratory birds and has been monitoring migratory shorebirds soon after their arrival in this country since 1984.
In the last two years, almost 2000 samples were collected from bar-tailed godwits, knots and wrybills (a non-migratory wader that is in very close contact with the migrants from the time of their arrival in New Zealand) and mallard ducks in the vicinity of arrival locations. No H5N1 or highly pathogenic avian influenza viruses were isolated from any of these samples, or from the less intensive sampling that was conducted in previous years.
MAF will continue to conduct surveillance in line with World Organisation for Animal Health (OIE) recommendations. It is important to note that New Zealand is considered low risk for avian influenza viruses of public health concern.
What is MAF doing about avian influenza?
New Zealand is well prepared to respond to an outbreak of avian influenza. MAF has comprehensive response plans and policies for highly pathogenic notifiable avian influenza (HPNAI) or any H5 and H7 subtypes of avian influenza as well as any other exotic strains of avian influenza of regulatory concern.
As a member of the World Organisation for Animal Health (OIE), New Zealand is expected to conduct surveillance to demonstrate our freedom from HPNAI.
HPNAI and all H5 or H7 subtypes of avian influenza that could mutate to become HPNAI are classed under the Biosecurity Act as a notifiable exotic disease in New Zealand. This means that any suspect cases must be notified to MAF immediately.
Why has MAF decided to increase surveillance?
Changes to the World Organisation for Animal Health (OIE) reporting requirements for avian influenza and expectations that New Zealand is part of a global network for early detection and warning for highly pathogenic notifiable avian influenza (HPNAI) infection means that more stringent avian influenza surveillance is needed.
MAF has increased its surveillance and response planning as preparedness activity. A comprehensive surveillance programme will look at wild birds, game birds, farmed ducks and geese, commercial chickens and backyard flocks over the next few years. It will provide the evidence needed to demonstrate to the OIE New Zealand’s freedom from HPNAI virus. MAF has been working with the poultry industry to put in place the most effective surveillance strategy. Phase one of the programme is conducting surveillance for avian influenza in layer and broiler flocks.
What do you expect to find?
Surveillance may discover some evidence of low pathogenic notifiable avian influenza (LPNAI) since LPNAI virus exists at extremely low levels in our wild bird populations. This is not an immediate concern because LPNAI does not cause disease or only causes mild disease, and is not a human health concern.
New Zealand does not have highly pathogenic notifiable avian influenza (HPNAI). If it was present, it would be quickly evident in our commercial flocks. By increasing surveillance, New Zealand will be able to meet World Organisation for Animal Health (OIE) requirements for demonstrating freedom from HPNAI, in line with new reporting requirements.
What avian influenza viruses could affect human health?
Human health concerns relate mainly to specific global strains of H5N1 highly pathogenic notifiable avian influenza (HPNAI). The concern is that it might combine with current human-adapted influenza viruses and emerge as a new virus, which is easily spread between humans and causes significant disease that humans have no immunity to, thereby causing an influenza pandemic.
How will MAF respond if avian influenza arrives in New Zealand?
In the event of an outbreak of avian influenza in New Zealand, MAF would activate its Technical Response Policies and Operational Plans.
All highly pathogenic avian influenza virus will be eradicated. Responses to low pathogenicity notifiable virus infection will be phased eradication to prevent possible evolution to HPNAI. As with other animal disease responses, independent technical advice will be sought and a number of response options evaluated to decide the best response option.
In addition to enhanced biosecurity in collaboration with poultry owners, response options include:
- Quarantine
- Planned slaughter as part of normal management
- Culling
- Movement controls of risk goods
- Tracing and local surveillance to locate the source of infection and determine the extent of spread
How could H5N1 enter New Zealand?
Potential routes of entry include illegal imports of poultry and unprocessed poultry products or the movement of contaminated fomites (virus in avian faecal material on packaging, clothing, equipment etc and other commodities from infected areas). New Zealand prides itself on keeping disease at bay with strict biosecurity measures at the border and stringent testing regimes. Import Health Standards prevent entry in imported risk goods, and our unique major poultry disease-free status proves that this system is highly effective.
How does MAF prevent illegal entry?
MAF Quarantine Service staff inspect consignments of cargo, passengers, luggage and imported commodities using dogs and sophisticated X-ray equipment.
Does New Zealand import live birds from any of the affected countries?
No. There have been no imports of live birds into New Zealand since 1997, except for zoo species such flamingos.
Are New Zealanders at risk through food?
The New Zealand Food Safety Authority advises that avian influenza is not a risk in New Zealand in terms of food safety. Consumers can be confident that the raw poultry and table egg products purchased in New Zealand supermarkets are New Zealand produced and free from avian influenza.
There is no evidence that any of the human cases of avian influenza overseas occurred as a result of eating cooked poultry products. Human cases are generally a result of direct contact with live and infected birds or the consumption of raw poultry meat or blood.
Does New Zealand import any poultry products for human consumption from the affected countries?
There are some highly processed products which are imported including canned meat, chicken paste, powdered chicken stock, dried egg yolk and feathers. Any virus would have been killed during processing, posing no risk to either animal or human health.
Does New Zealand import hatching eggs?
Yes. New Zealand imports live chicken and turkey eggs from the United States, Canada, the United Kingdom and Australia. The eggs are hatched and the chicks reared in strict quarantine conditions under veterinary supervision, according to New Zealand import health standards. Strict biosecurity measures, stringent testing regimes for avian influenza and other exotic diseases and New Zealand’s major poultry disease free status proves that this system is highly effective.
Do products made from processed feathers and down pose a risk of introducing avian influenza to New Zealand?
No. The production processes used in the feather and down industry for washing, drying and separating feathers and down effectively kill any virus, posing no risk to either human or animal health. Strict New Zealand import health standards and biosecurity controls prevent unprocessed products from entering the country.
Will MAF vaccinate against bird flu?
Vaccination may be used in certain species or situations as a short-term measure when there is a significant and immediate threat of HPNAI spreading within New Zealand. Although vaccination reduces virus shedding and clinical signs, birds may still be infected and so vaccination should not be used without a specific monitoring programme. However, depending on the situation, and in consultation with experts, strategic emergency vaccination may be used in New Zealand to avoid local spread or to protect socially or culturally valuable collections or in threatened indigenous birds.
How can the public protect their birds?
The risk of H5N1 entering New Zealand in migratory birds is very low. Pet birds kept in your home should not catch avian influenza if you do not allow them to come into contact with wild birds, wild bird faeces or another introduced infected pet bird.
If you keep birds you should always follow simple biosecurity measures:
- Keep everything clean – spilled feed, litter and standing water attract vermin and wild birds
- If your birds are sick, contact your vet
What are the symptoms of bird flu?
The main symptoms to look for in poultry are:
- sudden and unexplained deaths
- rapid spread of disease throughout the flock
- depression and loss of appetite
- a drop in egg production
- signs of nervousness
- swelling and blue combs and wattles
- coughing, sneezing and diarrhoea.
Mortality may be extremely high with entire flocks dying over just a few days.
Please call your regular animal health advisor, or alternatively, the MAF Emergency Pest and Disease Hotline on 0800 80 99 66 if you suspect your birds may be infected with avian influenza.
I have chickens; what can I do to protect them?
Limiting contact between poultry flocks and wild birds (whether migratory or not) through good biosecurity practices is crucial in minimising the likelihood of entry of any type of avian influenza virus. This means that water and feed supplies for poultry flocks must be managed so that they do not become contaminated with faeces of wild birds. Equipment should not be shared between flocks without cleaning and disinfection.
What should I do if I see sick or dead wild birds?
You can play a significant role by reporting anything unusual, such as large numbers of sick or dead birds, to the Emergency Pest and Disease Hotline on 0800 80 99 66. Avian influenza is classed as a notifiable exotic disease under the Biosecurity Act; this means that any suspect cases must be notified to MAF immediately.
Is there a risk of migratory birds contaminating drinking water?
The risk of highly pathogenic notifiable avian influenza (HPNAI) entering New Zealand in migratory birds is very low. As protection from a range of diseases carried in bird faeces, you should follow good hygiene practices and ensure that reservoirs and storage tanks are covered.
Why is there concern about the current outbreak?
International concern relates to highly pathogenic H5N1 virus and the way it appears to have been spreading in a wide range of wild and captive birds. Not all H5N1 viruses are pathogenic and not all birds are equally susceptible to pathogenic strains. H5N1 virus infection may therefore occur in some birds without causing disease. Mammals (including humans) have been infected with H5N1 but these are aberrant hosts and have not to date been implicated in the spread of infection.
While there is no suggestion yet that the virus is easily spread from person to person, fatal human infections have led to the concern that H5N1 could contribute to the next human flu pandemic should this virus combine with a human adapted influenza virus.
How does H5N1 spread to humans?
Human have caught H5N1mainly through very close and prolonged contact with poultry in places such as markets and poultry farms, where there is a high density of different species of bird mixing, and where they are exposed to both live and dead birds and their droppings.
There is little risk of people in New Zealand being infected through normal contact with birds. New Zealand does not have live bird markets and our commercial poultry industry operates under strict biosecurity measures. New Zealand's major poultry disease-free status proves that our systems are highly effective.
What is pandemic human influenza?
Avian influenza viruses are highly unstable and are always changing. The evolution of low pathogenicity avian influenza virus into a highly pathogenic disease in birds occurs infrequently. In extremely rare cases a HPAI virus can mutate and emerge as a new human-adapted influenza virus, which is easily spread between humans and causes significant disease that humans have no immunity to, thereby causing an influenza pandemic.
There have been three global outbreaks of influenza:
1. Spanish Flu 1918 resulted in 40-50 million deaths (H1N1)
2. Asian Flu 1957 resulted in 1-4 million deaths (H2N2)
3. Hong Kong Flu 1968 resulted in 1-4 million deaths(H3N2)
Genetic studies have shown that human pandemic influenza viruses have been derived from birds. The risk of a new virus emerging is greatest in areas where there is close contact between humans and animal populations (primarily poultry and possibly pigs) with high endemic levels of infection i.e. as currently in Asia.
Can the virus spread between humans?
There is no evidence of H5N1 being readily transmitted from one person to another. Adaptation to, and evidence of, spread between humans would indicate the emergence of a potential human influenza pandemic.
Many thanks to Biosecurity New Zealand for providing us with this information. (Note: was last updated on the 3rd of July with a version provided on the 3rd of July, 2006).
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