Frequently asked questions on A(H7N9) virus

Updated 27 May 2013

What is the avian influenza A(H7N9) virus?

H7N9 is a new subtype of avian influenza virus. The current H7N9 virus is a reassortant (i.e. mix) of viruses previously detected in wild birds and poultry. The recent event in China represents the first ever report of H7N9 virus in humans.

What are the main symptoms of human infection with avian influenza A(H7N9) virus?

Thus far, patients with this infection have had severe pneumonia. Symptoms include fever, cough and shortness of breath. However, information is still limited about the full spectrum of clinical signs due to infection with the H7N9 virus. Source: WHO

How is H7N9 associated with animals?

Chinese authorities have officially reported their detection of this H7N9 virus in bird samples collected from chickens, ducks and captive-bred pigeons at live bird markets in areas where humans have been affected. Additionally, Guangdong province has detected the virus in chickens in LBMs without any links to human cases.
The only previous reports of infections with this virus subtype in Asia in animals come from surveillance activities in 2008 in the Republic of Korea and Mongolia where H7N9 subtype was isolated from wild birds. It is important to note that H7 viruses and their subtypes (e.g. H7N2, H7N6, and H7N7) have been identified in poultry from many counties throughout the world.

Are wild birds affected?

There has been no evidence of infection of this particular H7N9 virus in wild migratory birds in China since the virus was first identified. Surveillance efforts in wildlife and environmental sampling are ongoing in affected areas. FAO advises strongly against culling wild birds. Poultry and other domestic animals should be kept separate from wild birds and other wildlife.

What is the source of the avian influenza A(H7N9) virus that is infecting humans?

The source of infection has not yet been confirmed. A number of the human H7N9 cases in China have reportedly had contact with domestic poultry.

The Chinese authorities are conducting an extensive surveillance programme in domestic livestock throughout the country to gather further information.

The genetic analysis of the viruses isolated show components that are avian in origin, but the precise source of these human infections has yet to be determined.

How is this virus different from highly pathogenic viruses like H5N1, so called "bird flu"?

Generally viruses of H7 subtypes are referred to as low pathogenic when they cause mild or no disease in domestic poultry. Genetic analysis of the avian influenza A(H7N9) virus shows that  it is low pathogenic for chickens and animal experiments have shown that birds do not show any clinical signs after experiential infection. Low pathogenic viruses are difficult to detect in chickens since infected birds often do not show any signs of illness.

In contrast, highly pathogenic avian influenza viruses, like some H5N1 strains, cause severe disease and high mortality in chickens. This makes H5N1 and other highly pathogenic viruses easier to detect in poultry. For more information on H5N1, see FAO's FAQ on H5N1 highly pathogenic avian influenza:

It is important to note that some low pathogenic H7 viruses have evolved into highly pathogenic avian influenza viruses, as had been observed in Canada (2004), Chile (2002) and various countries in Europe.

What should be done to protect humans from influenza viruses?

FAO recommends following WHO guidelines with regard to human health concerns. See WHO's Frequently Asked Questions on human infection with influenza A(H7N9) virus, China

What precautions should be taken by authorities in a country affected by avian influenza?

It is important that countries have a well-resourced veterinary system in place for the prevention, detection and rapid response for the incursion of an animal pathogen or other threat.  Facilities are required for quarantine of live animals or inspection of animals and products. Well prepared teams of diagnosticians to conduct field investigations and laboratory testing are essential to inform decision makers as to the nature of the problem and trigger a response.

Low pathogenic influenza viruses are difficult to detect in birds because they cause only mild or no disease in poultry.  Farmers should look for subtle disease signs like a slight drop in egg production or lowered feed intake. Surveillance of live bird markets along with hygiene and disinfection practices in markets is highly recommended.

In the past, countries infected with low pathogenic avian influenza have relied on: i) targeted surveillance; ii) strengthened biosecurity at the farm and market level; and sometimes iii) the use of quality controlled vaccine. Some countries have eliminated low pathogenic avian influenza viruses through culling and compensation schemes.

Is FAO recommending the vaccination of animals against H7N9?

FAO considers it premature to recommend the vaccination of animal species against avian influenza A(H7N9). The degree to which the virus is circulating in animals is still unknown. Although commercial vaccines exist for H7 viruses, more information is needed to determine whether or not those vaccines can be effective against this new virus or if an appropriate vaccine would need to be developed.

If vaccination in animals were to be considered, what factors would be required to plan a vaccination campaign?

Vaccination aims to protect susceptible [animal] populations from potential infection. Vaccination reduces the amount of virus excreted by animals, thereby reducing the virus' capacity to spread. Vaccination strategies can effectively be used as an emergency effort in the face of an outbreak or as a routine measure in an endemic area. Source: OIE

Knowing where an infection is circulating is required before deciding to use vaccine. Vaccination alone does not resolve the risk to humans and needs to be complemented with improved production and market hygiene and systems of certification to protect workers and consumers.

Careful planning, including coverage of all logistical requirements, is important in deciding whether vaccines could be applied for a successful outcome. Training should also be carried out to ensure vaccinators understand the principles of biosecurity and biosafety so vaccinators do not aggravate the spread of the virus. Authorities should also include a plan to reach conditions in which vaccines should be withdrawn and vaccination stopped (i.e. an exit strategy).

What precautions should be taken by the general population in a country affected by avian influenza?

FAO recommends following good biosecurity and farm hygiene practices throughout the poultry and other animal marketing chain. While H7N9 seems to cause little to no signs of illness in birds, standard, good biosecurity and hygiene measures will still help protect animals and people from this and other influenza viruses in general. FAO recommends that you:

In the case of mild or no illness in livestock or wildlife populations, surveillance and sampling at points of concentration (such as live animal markets or fairs) should take place to see if the virus is circulating. 

Strengthened biosecurity at family farms, commercial operators and marketplaces will assist in reducing the risk of virus introduction.

Keep all birds and livestock separate from people and living areas. Close contact with infected animals can put people at risk. Since the avian influenza A(H7N9) virus causes little to no signs of disease in birds, separate living areas for animals and people is key.

Birds affected with low pathogenic avian influenzas like H7N9 often do not show clinical signs of disease. However, it is still important to report any clinical cases of sick or dead birds that you encounter to the local veterinary (or public health) authorities. If this is not possible, tell your neighbours or community leaders. It is important to report all signs of illness or sudden and unexplained deaths in poultry, wild birds, or other animals so veterinary services can investigate the cause, take samples for submission to the diagnostic laboratory and dispose of the carcases properly.

Keep wild birds away from poultry and other animals, and keep different types of animal species apart. Screens, fencing or nets can be used to separate species and help prevent transmission.

Wash your hands often to kill and remove viruses and other disease causing agents. You should always wash after handling birds or other animals, cooking or preparing food products and before eating.

What specific precautions should be taken by individuals involved in the sale or transport of poultry?

Poultry producers, transporters, sellers and all other intermediaries in the poultry value chain should use good biosecurity measures to minimize the risk of incursion of the virus into individual production units and the risk of outward and onward transmission through the market chain.

Transporters of live birds should use cages that: i) are only used for the purpose of transporting birds, and ii) can be easily cleaned and disinfected. All devices used for moving live poultry should be cleaned and disinfected before and after transport.

Veterinarians and other service providers who travel from site to site risk spreading disease if good biosecurity measures are not practiced. Veterinarians should also promote the use of good biosecurity measures to poultry keepers and other actors they encounter.

At farm level,  good biosecurity measures should be implemented. These include: creating physical barriers at farm entrances, using water and feed sources that are free from contaminants, employing poultry housing that effectively resists wild bird and rodent infestation, preventing poultry unit workers from keeping their own poultry, ensuring outer clothes and footwear are changed upon entry and exit, establishing mandatory rest periods (e.g. minimum 1 day) between farm visits to avoid the risk of intermediaries transferring the disease from one site to another, imposing quarantines on newly introduced or returning birds, keeping animal species separate and thoroughly cleaning and disinfecting premises on a regular basis.

What are appropriate hygiene measures to be implemented in live bird markets?

Instituting proper hygiene at live bird markets requires the consultation and involvement of all stakeholders (e.g. market operators, stall holders, local authorities, veterinary services, public health services and sellers). Markets should be easy to clean and disinfect regularly.

Market infrastructure improvements may be required, including installation of solid, easily washable flooring, effective waste disposal systems, proper drainage and reliable running water supplies. Holding cages should be easy to clean.

Markets practicing the slaughter of animals should be distinct from markets that maintain breeding animals. Furthermore, wholesale markets should be distinct from retail markets, and individual poultry species held at the market should be kept separate from one another. At retail markets where birds are slaughtered, workers should use protective clothing and equipment that can be easily cleaned and disinfected.

FAO is currently providing support to many countries in the improvement of live animal market infrastructure and organization.

What role do live bird markets play in the current situation?

More information is required to understand what role live bird markets may or may not have in the current situation.
In general, live bird markets likely have an important role in receiving and disseminating avian influenza viruses. Current information suggests live bird markets may even be responsible for virus mixing between species including humans.

Therefore, FAO is recommending enhanced, regular surveillance in live bird markets, especially considering that the majority of human cases found to date appear to have had a link to live bird markets. If positive animals are found in these markets, it is critical to trace the infection back to the farm of origin. Tracing back allows authorities to: i) better understand the extent of virus spread; ii) help identify the source of infection; and iii) target and implement appropriate control measures.

Is poultry meat safe for consumption?

Influenza viruses are not transmitted through consumption of well-cooked food. Influenza viruses are inactivated by normal temperatures used for cooking (so that food reaches 70°C in all parts- "piping" hot), it is safe to eat properly prepared and cooked meat, including from poultry and game birds.

Diseased animals and animals that have died of diseases should not be eaten. Do not give or sell these dead animals to other people. Such animals should also not be fed to other animals.

Meat products can be safely consumed provided that these items are properly cooked and properly handled during food preparation. The consumption of raw meat and uncooked blood-based dishes is a high-risk practice [for several food-borne microbes] and should be discouraged.  Egg and egg-containing dishes should also be fully cooked. 

Source: WHO and FAO

What are good food preparation practices?

Proper food preparation includes:
hand washing before and after handling food;
hand washing in between handling raw food and cooked or ready-to eat food;
keeping raw meat separate from cooked or ready-to-eat foods;
keeping utensils and surfaces used to prepare raw meats separate from those used for other foods (e.g. chopping boards, knives and plates);
washing and disinfecting all surfaces and utensils that have been in contact with raw meat.

Source: WHO and FAO

What is FAO doing?

FAO is monitoring the situation closely through its wide network of country offices, reference centres and other collaborators.

FAO is liaising with key partners, including the World Health Organization (WHO) and the World Organisation for Animal Health (OIE).

FAO and the scientific community are currently studying the virus sequences in order to better understand its properties and ensuring diagnostic approaches are able to detect this new strain of influenza virus.

FAO has set up a website for H7N9 and has posted guidelines for surveillance, risk assessment and risk management for avian influenza A(H7N9) for affected and at risk countries.

What is FAO's opinion on the actions of Chinese authorities?

FAO concurs with China's current management of the situation based on the information available.

FAO concurs with the recommendations of Chinese authorities for the public to take routine care to prevent transmission of respiratory infections and to pay special attention to avoid direct contact with sick or dead poultry and livestock.

FAO commends the Chinese authorities' decision to release virus information to the public. This has allowed the scientific community to perform further analysis and for countries to initiate efforts for early detection, prevention and control.

Should China be testing healthy birds for the virus in areas where human infections have been reported?

Yes. China has already begun this activity. FAO compliments China for its efforts in animal surveillance activities, and FAO is in the position to offer assistance to countries in this regard. Chinese authorities have increased sampling of poultry, wildlife and pigs in areas where human cases have been reported. Sites include live bird markets, intensive production sites and smallholder sites.

Is FAO recommending any trade restrictions at this time?

FAO recommends importing countries uphold international standards to ensure veterinary systems for live animal screening, certification and the control of goods.  These measures promote the import of healthy and wholesome products and/or animals.

Trade restrictions should always be reviewed in relation to the level of risk posed by specific animal products to a country. In the case of H7N9 in China, the reservoir or carrier of the virus has yet to be confirmed. Knowing which species serve this function is essential when dealing with animal diseases in order to target response actions accordingly, including trade restrictions. 

For additional information on trade-related aspects please visit:

Where can I get more information on influenza in humans?

Where can I get more information on biosecurity?

The below-mentioned references refer specifically to highly pathogenic avian influenza H5N1. However, their content is serves equally well in the management of H7N9.

Biosecurity HPAI Paper:
Biosecurity fact sheet:
Biosecurity brochure:
Biosecurity booklet:

Photo: ©FAO/Tariq Tinazay / FAO
Strong biosecurity and hygiene measures are essential to reducing the risk of A(H7N9) virus transmission.