Public health priority: Urgent. Respond to a suspected case immediately on notification. Report details of the case to [Communicable Disease Branch (CDB)] within 1 hour of notification. [CDB] should report confirmed cases to the National Incident Room on day of notification. Data entry should be completed within the same working day.
Case management: Suspected cases must be cared for in a single room, and if available, a negative pressure room. Cases should be treated with neuraminidase inhibitors, ideally within 48 hours of onset.
Contact management: Contacts of confirmed cases and infected birds must be rapidly identified, counselled about their risk, provided with neuraminidase inhibitors (if indicated), and placed under surveillance for 10 days after the last exposure.
Revision history
This guideline is concerned with the public health response to people with avian influenza (AI) infection, and people who have been exposed to another person or birds with AI infection.
It is not concerned with human pandemic influenza. In the unusual event that an AI strain transforms into one that is easily transmitted between humans, it is no longer avian influenza, but becomes human (and possibly pandemic) influenza. The response to human pandemic influenza is described in the national and state influenza pandemic management plans. The pandemic phases are outlined in the Australian Heath Management Plan for Pandemic Influenza.1 The case definitions have been developed to apply to all AI strains regardless of their pathogenicity classification in birds (see section 7). This recognises that any strain of avian influenza could emerge as a public health threat.
Urgent. Respond to a suspected case immediately on notification. Report details of the case to [Communicable Disease Branch (CDB)] within 1 hour of notification. [CDB] should report confirmed cases to the National Incident Room on day of notification. Data entry should be completed within the same working day.
Suspected cases must be cared for in a single room, and if available, a negative pressure room. Cases should be treated with neuraminidase inhibitors, ideally within 48 hours of onset.
Contacts of confirmed cases and infected birds must be rapidly identified, counselled about their risk, provided with neuraminidase inhibitors (if indicated), and placed under surveillance for 10 days after the last exposure.
Infectious agents Avian influenza A virus. All AI viruses are influenza A viruses which are further divided into subtypes determined by haemagglutinin (H) and neuraminidase (N) antigens. At present, 16 H subtypes and 9 N subtypes have been identified in birds. Each AI virus has one of each H and N subtype occurring in many different combinations. The virulence is associated with the genetic properties of the virus.2 AI viruses are classified as highly pathogenic avian influenza (HPAI) and low pathogenicity avian influenza (LPAI) in conformity with criteria established in relation to poultry by the World Organisation for Animal Health (OIE).3 Hence the use of the terms HPAI or LPAI only refers to the virulence of the AI virus in birds. To date, only H5 and H7 subtypes have been known to cause outbreaks of HPAI in birds. Both LPAI and HPAI viruses can however rarely cause illness in humans following very close contact. It is believed that human pandemic influenza strains may arise from AI viruses.2 No assumption can be made about the clinical significance of a novel AI virus in humans based on the pathogenicity designation in birds.4 One HPAI strain, the H5N1 avian influenza virus, has caused serious infections in humans and deaths during poultry outbreaks overseas.5 One LPAI, H7N9, has caused serious infections in humans and deaths in China however has not been linked with clinical disease in birds.6
Note: As information as to risks and timelines becomes better documented public health staff should review the latest literature on transmission and timelines during investigations.
The species in the orders Anseriformes (ducks, geese, swans) and Charadriiformes (shorebirds, waders, gulls) are regarded as important reservoir hosts and disseminators of AI viruses, but rarely display clinical signs of infection.2 In this document, these reservoir birds are referred to collectively as “waterbirds”. However it is reasonable to assume all avian species are susceptible to AI infection.3
Infected birds may shed virus in their saliva, nasal and respiratory secretions, and faeces depending on many factors such as the type of bird, the virus subtype and the presence of other diseases. Faeces of infected birds can contain large amounts of virus with faecal-oral transmission the predominant mode of spread between birds. Asymptomatic waterbirds may directly or indirectly introduce the virus into poultry flocks via contaminated excretions from infected birds or via contaminated environments.7 Secondary dissemination is by fomites, movement of infected poultry, and possibly airborne. LPAI infection is primarily a localised infection in poultry and HPAI infection typically presents as a more systemic infection.7
Transmission of AI infection from birds to humans is rare. When it has occurred, it is believed to have resulted from close contact with infected poultry or breathing in dust contaminated with their excretions. The virus can survive on poultry products (including eggs and blood),8 however no infection has been documented from eating properly cooked eggs and meat from infectious birds. Transmission has been thought to occur by ingesting uncooked poultry products (including raw blood) from H5N1 infected poultry.9
The spread of AI viruses from one ill person to another through prolonged, unprotected, close contact has been reported very rarely, and has been limited, inefficient and not sustained.10-11
The incubation period for AI in humans may be longer than that for normal seasonal influenza, which is around two to three days. Current data indicate an incubation period will typically (and for public health purposes should be considered to) range from one to ten days.11-13 This may vary depending on the AI strain.
No detailed studies have been conducted of infectivity of AI viruses in humans. Viral shedding of H5N1 has been detected in some patients up to 21 days after symptoms begin,14-15 and up to 20 days after symptoms begin for H7N9 patients,16 however the low number of secondary cases detected indicates that viral shedding is not an accurate reflection of AI infectivity in humans.
Based on data on human influenza subtypes:
The clinical presentation of AI in humans may be highly variable both between and within haemagglutinin subtypes. As with seasonal human influenza, a person infected with AI may have no symptoms, mild upper respiratory symptoms, or symptoms typical of influenza (fever, cough, fatigue, myalgia, sore throat, shortness of breath, runny nose, headache); diarrhoea may also occur.5
Mild symptoms, including conjunctivitis and gastrointestinal symptoms, have been typically associated with several AI subtypes and should be considered in any person who has had close exposure to birds infected with any subtype of AI.8 An outbreak of LPAI H10N7 on a chicken farm in Australia was associated with conjunctivitis and mild respiratory symptoms in seven abattoir workers processing birds from this farm. H10 influenza subtype was laboratory confirmed in two of the cases.12 A large outbreak of HPAI H7N7 in the Netherlands in 2004 was reported to have resulted in a rate of conjunctivitis of 8%, influenza like illness in 2%, and one death associated with respiratory failure in those exposed.28
The H5N1 subtype has caused viral pneumonia with a high case fatality rate, and in a small number of cases, diarrhoea, vomiting, abdominal pain, chest pain, and bleeding from the nose and gums have also been reported as early symptoms.5 Initial data on the H7N9 subtype which emerged in eastern China in February 2013 indicates that human illness is characterised by rapidly progressive pneumonia, respiratory failure and acute respiratory distress syndrome (ARDS) with a high case fatality. However some confirmed cases, particularly young children, have been asymptomatic or associated with clinically mild upper respiratory illness.6,11
The likely scenarios in which a human infection with avian influenza could occur in Australia are:
As of June 2015 there have been no known bird or human cases in Australia associated with the H5N1 or H7N9 viruses which have caused human illness and death overseas. Recent poultry outbreaks of HPAI H7 (2012 and 2013),29-30 LPAI H4 and LPAI H9 (2012)31 and LPAI H10 (2010)12 subtypes have been recorded in New South Wales; only the H10 subtype was associated with recognised likely transmission of mild illness to humans. An LPAI H5 outbreak also occurred in a Victorian duck farm in 2012.32
The prevention of AI in Australians principally relies on:
Various strains of AI are enzootic in bird populations around the world. Outbreaks in Australian domestic poultry have been associated with poor biosecurity, confirmed or circumstantial evidence of contact with waterbirds, or inadequately treated surface water potentially contaminated by waterbirds or domestic ducks.34 AI-contaminated materials carried by humans or material brought into Australia from AI-infected countries may also pose a risk of infecting poultry or humans.
Biosecurity measures have been put in place in many commercial bird facilities to minimise the risk of future AI infections in birds. However, many facilities (notably free range farms) may present opportunities for exposure of domestic poultry to waterbirds and/or their excretions. Strict quarantine and inspection measures at Australian airports and seaports are designed to prevent the importation of bird products into Australia. [NSW Department of Primary Industries (DPI)] have contingency plans in place to minimise the impact of an outbreak of AI in Australia. These procedures are outlined in the Australian Veterinary Emergency Plan (AUSVETPLAN).2
People co-infected with avian influenza and human influenza infections are thought to provide the potential for re-assortment of genes from the two strains of influenza that could result in a new human pandemic influenza strain. Therefore, if human influenza is currently circulating in the community, poultry workers and other people directly involved in culling AI infected poultry should be vaccinated with the current recommended seasonal influenza vaccine. While vaccination will not prevent AI, it will help reduce the risk of co-infection, re-assortment and a pandemic.35
Within 1 working day of confirmation, enter confirmed case on [the Notifiable Conditions Information Management System (NCIMS) database.]
Immediately report suspected and confirmed cases of AI in humans to [CDB] by telephone with the patient’s age, sex, date of onset, laboratory status, possible sources of infection, other people thought to be at risk and follow up action taken. Any suspect or confirmed AI infected bird(s) should also be reported to [CDB] to assess the risk of infection in human contacts.
The [NSW CDB] should immediately notify confirmed human AI cases to the National Incident Room, and the [NSW DPI].
Avian Influenza in Humans (AIH) Case Definition
Both confirmed cases and probable cases should be notified. Suspected cases should not be notified.
A confirmed case requires laboratory definitive evidence and clinical evidence
Note: Tests must be conducted in a national, regional or international influenza laboratory whose AIH test results are accepted by WHO as confirmatory
An acute illness characterised by:
A probable case requires laboratory suggestive evidence and clinical evidence and epidemiological evidence.
Confirmation of an influenza A infection but insufficient laboratory evidence for AIH infection.
As with confirmed case.
One or more of the following exposures in the 10 days prior to symptom onset:
A suspected case requires clinical evidence and epidemiological evidence.
As with confirmed case
As with probable case.
Note: For overseas exposures, an AI-affected area is defined as a region within a country with confirmed outbreaks of AI strains in birds or detected in humans in the last month (seek advice from the National Incident Room when in doubt). With respect to the H5N1 AI outbreak that commenced in Asia in 2003, information regarding H5-affected countries is available. With respect to the H7N9 outbreak that commenced in eastern China in 2013, see WHO information regarding H7-affected countries.
Laboratory confirmation should be urgently sought to confirm all suspected cases. Consult with the virologist, but nose and throat swabs (usually for adults) and conjunctival swabs (even in the absence of conjunctivitis) are recommended. Sputum specimens may be more effective for detecting H7N9 and are recommended wherever possible.37
Collect baseline and convalescent sera for symptomatic cases. Do not collect sera for asymptomatic contacts.
Viral swabs should be collected and transported using viral transport medium (VTM) or universal transport medium (UTM).
Samples should be tested at a reference laboratory using:
Nasopharyngeal and throat swabs may induce coughing and should preferably be collected in a negative pressure room, if available, by health care workers (HCWs) wearing full PPE.38 Write on specimen forms and containers before entering the patient’s room to collect the specimens.
The laboratory should be notified in advance by telephone that the specimens will be sent, and specimens should be clearly marked URGENT: SUSPECTED AVIAN INFLUENZA to ensure prioritisation by the laboratory.
Specimens should be packaged and transported according to the National Pathology Accreditation Advisory Council (NPAAC) requirements.39 Diagnostic specimens for AI testing are classified as Biological Substances, Category B. Amplified viable material including viral cultures are classified as Infectious Substances, Category A. The Public Health Laboratory Network may advise on packaging and transport of these specimens.
As AI is often an unlikely diagnosis in most suspected cases, other relevant tests should be done concurrently to identify an alternative diagnosis.
Immediately on notification of a suspected case, begin follow up investigation and notify the [CDB]. For confirmed and probable cases, the “Avian Influenza (AI) in humans - Investigation Form” (see appendices) should be completed and data transferred to the [CDB] the same day.
The response to a notification will normally be carried out in collaboration with the case’s health carers. Regardless of who does the follow-up, for confirmed cases, PHU staff should ensure that action has been taken to:
Note. If interviews with suspected cases are conducted face-to-face, the person conducting the interview must have a thorough understanding of infection control practices, be competent in using appropriate personal protective equipment (PPE),39-40 and ideally have been vaccinated with the current (human) influenza vaccine.
Treatment of a case is the responsibility of the clinician in consultation with an expert virologist. Neuraminidase inhibitors (e.g. oseltamivir or zanamivir) have been shown to attenuate disease in cases of human influenza if started within 5 days of the onset of illness (ideally within 48 hours).1 They may also be effective for treating AI.
Provide the [NSW Health Avian Influenza (“Bird Flu”) Fact Sheet] to cases. Ensure that they are aware of the signs and symptoms of AI, the requirements of isolation, contact details of the PHU and the infection control practices and precautions that can prevent the transmission of AI.
Infectious cases must be isolated until no longer infectious (see Section 2). Advice from the facility’s infection control professional should be sought. Health care workers and others who come into contact with the case must use airborne, droplet, contact and standard infection control precautions including appropriate PPE (gown, gloves, protective eyewear and P2 respirator).40-41
The mode of transmission is unclear, but postulated to be mainly droplet and direct contact. However, the possibility of airborne transmission remains, and airborne precautions must be used.
Patients should be managed in a single room with airborne, droplet, contact and standard precautions and if available, a negative pressure room. Similarly, in a primary care setting such as a GP surgery, patient isolation and, droplet, contact and standard infection control precautions should be employed.39-40 Acute cases should be managed in hospital. When discharged home, a comprehensive discharge plan must be made by the treating hospital.
Where transmission has been identified from poultry to humans, Public Health Units should actively search for other cases in people who were exposed to the infected poultry and initiate active surveillance in these people for the duration of the infectious period.
Where local transmission of AI is thought possible, a thorough review of contributing environmental factors should be performed. If transmission is thought to be poultry-related, the environmental assessment should include a review of opportunities for exposure to infected birds, in collaboration with [NSW DPI] and the [SafeWork NSW] . If health care-associated infection is suspected, the adequacy of infection control procedures must be reviewed.
Staff conducting the environmental evaluation must have a thorough understanding of infection control practices, be competent in using personal protective equipment (PPE), and have been vaccinated with the current (human) influenza vaccine. They must follow airborne, droplet, contact and standard infection control precautions, including appropriate PPE (gown, gloves, protective eyewear and P2 respirator).33
AI is not easily transmitted between humans, and probably requires close and prolonged contact. Public health interventions need careful consideration on a case-by-case basis. Following a report of a confirmed case, an expert panel should be convened by [CDB] to help plan the public health response. The expert panel may include experts in human influenza and poultry influenza, animal health agencies, virologists, infection control, infectious disease physicians and PHUs. [The panel should include a local PHU Director where the case is associated with a certain geographical area.]
The evidence base for defining what constitutes “contact” with a case is limited. For the purposes of the contact definition, it is taken to mean being within one metre (e.g. caring for, speaking with, or touching) of an infectious case within the previous 10 days, in the absence of appropriate infection control. The expert panel will advise on a more specific contact definition as required. Where a case has travelled on an aeroplane, contacts are defined as persons sitting in the seats immediately beside the case, due to the lower rate of person-to-person transmission of AI viruses. However, the expert panel should advise on contacts to be traced.
Antiviral medications may be effective in preventing disease in contacts. Unless the available evidence clearly shows a lack of efficacy, close contacts of confirmed cases will generally be offered neuraminidase inhibitors (e.g. oseltamivir or zanamivir) to prevent infection. The expert panel will provide more specific advice as needed.
Contacts should be counselled about their risk and the symptoms of AI and placed under surveillance (see Appendix 3 “Avian influenza (“bird flu”) advice for people under surveillance” in appendices).
Contacts are not required to isolate themselves from the community but must adhere to advice regarding self-monitoring until the incubation period expires (see section 2).
The PHU should ensure that contacts are communicated with daily for 10 days after the last exposure to determine if symptoms of AI have developed. If symptoms develop, the contact must be rapidly isolated until AI is excluded. The PHU should arrange assessment by an appropriately skilled medical practitioner. This must take place in a setting where risk is managed through the use of appropriate infection control precautions. If this occurs at an emergency department, arrangements should be made to ensure that the patient does not wait in any common areas and will be placed immediately in a single room, ideally with negative pressure for assessment.
Where the [NSW DPI] reports any outbreak of AI in birds in Australia, the PHU is responsible for ensuring that the risk of human infection is minimised. The public health actions should be guided by the expert panel convened by the [CDB].
Issues to be addressed include:
The following documents are included as appendices:
Links to State and Territory Public Health Legislation, the Biosecurity Act 2015 and the National Health Security Act 2007.
[Note that human influenza with pandemic potential is a listed disease under the Biosecurity Act and that highly pathogenic avian influenza (human) is a nationally notifiable disease under the National Health Security Act. Avian influenza is a notifiable disease in NSW under the NSW Public Health Act (2010)]