What is the H7N9 influenza?
Influenza (A)H7 viruses are a group of influenza viruses that normally
circulate among birds. H7N9 is a reassortant derived from three
different avian influenza viruses. This strain is distinct from the H1N1/09
(that caused the 2009 pandemic in humans) and H5N1 influenza. H7N9 that is
genetically similar to that detected in infected humans has been detected
in pigeon and poultry samples collected at a live animal market in
Shanghai. Unlike other influenza strains, including highly pathogenic
avian influenza H5N1, this new virus is hard to detect in poultry because
this novel virus causes little to no signs of disease in animals. Although
there is no evidence of human-to-human transmission of H7N9 to date,
sequence analysis indicates the virus has properties to infect mammalian
cells; therefore, the potential for avian-human and human-human
transmission exists but requires further investigation. Sequences
previously associated with high virulence of A(H7) in humans (PB2 gene)
have been detected in isolates in the current outbreak.
What is the current situation?
See WHO website on the current situation, including epidemiological
updates, Q&A and guidance documents: Disease Outbreak
News Influenza at the Human-Animal Interface
- A total of 21 cases have been reported from China, including six
deaths. To date cases have been reported from four eastern provinces of
China (Shanghai, Anhui, Jiangsu and Zhejiang).
- There continues to be no evidence of human-to-human transmission
with medical observation of over 530 contacts ongoing. In
Jiangsu, investigation is ongoing into a contact of an earlier
confirmed case who developed symptoms of illness.
- The incubation period is not precisely known.
- There is currently no vaccine available for H7N9 influenza.
Laboratory testing conducted in China has shown that the influenza
A(H7N9) viruses are sensitive to neuraminidase inhibitors (oseltamivir
and zanamivir). When these drugs are given early in the course of
illness, they have been found to be effective against seasonal
influenza virus and influenza A(H5N1) virus infection. However, at this
time, there is no experience with the use of these drugs for the
treatment of H7N9 infection.
- From 1996 to 2012, human infections with H7 influenza viruses
(H7N2, H7N3, and H7N7) were reported in Netherlands, Italy, Canada,
USA, Mexico and the United Kingdom. Most of these infections occurred
in association with poultry outbreaks.
What are the symptoms?
H7N9 was initially identified in patients with severe pneumonia and/or
Acute Respiratory Distress Syndrome (ARDS) but 3 recent cases have been
mild. Symptoms include fever ≥ 38°C, cough and shortness of breath.
However, information is still limited about the full spectrum of disease
that infection with influenza A(H7N9) virus might cause. Symptoms and signs
of A(H7) infections during previous outbreaks mainly resulted in
conjunctivitis and mild upper respiratory symptoms, with the exception of
one death, which occurred in the Netherlands.
Are health workers at risk from H7N9 influenza?
The routes of transmission to humans of the H7N9 influenza have not yet
been fully determined, but there is currently no evidence that this strain
can spread from human to human. Infection control recommendations in this
document for suspected, probable and confirmed cases aim to provide the
highest level of protection for health care workers, given the current
limited state of knowledge.
Has WHO recommended any travel or trade restrictions related to this
The number of cases identified in China is very low. WHO does not advise
the application of any travel measures with respect to visitors to China
nor to persons leaving China. There is no evidence to link the current
cases with any Chinese products. WHO advises against any restrictions to
trade at this time.
Who do I test for H7N9 influenza?
Testing should be considered for:
- Individuals with acute pneumonia or pneumonitis and history of
travel to, or residence in China within the previous 7 days.
- Individuals with acute pneumonia or pneumonitis and history of
contact with those in point 1 above.
- Health care workers with acute pneumonia, who have been caring for
patients with severe acute respiratory infections, particularly
patients requiring intensive care, without regard to place of residence
or history of travel.
How do I test for H7N9?
- Where H7N9 infection is suspected, samples should be referred to
the Victorian Infectious Diseases Reference Laboratory for testing.
Specimens can be handled and transported routinely. They should be
clearly identified as requiring urgent testing for influenza A/H7N9,
and separated from non-urgent specimens. The reference laboratory
should be notified.
- Collect combined nose and throat swabs (usually from adults) or
nasopharyngeal aspirates (usually from children) and place in viral
transport medium. Sputum is strongly recommended wherever possible.
Bronchoalveolar samples and lung biopsy should also be sent if
- Gloves, gown, P2 respirator and eye protection should be worn as a
minimum when collecting samples from patients. If a negative pressure
room is unavailable, the patient should be placed in a single room with
the door closed.
- Testing for other infectious causes can be undertaken at the
referring laboratory using PC2 precautions, processing of samples in a
biosafety cabinet and use of PPE including a surgical mask and eye
protection. Routine tests for acute pneumonia should be performed where
indicated, including bacterial culture, serology, urinary antigen
testing and tests for influenza viruses.
- The laboratory carrying out the influenza testing should
immediately refer all unsubtypeable or presumptive H7 influenza A virus
to VIDRL or the WHOCC in Melbourne.
- Laboratory staff should handle specimens under enhanced PC2
conditions, with handling of open samples in a biosafety cabinet and
the use of gloves, gowns, masks and eye protection. PC3 conditions are
required for virus culture.
Further details about specimen collection and testing can be found
in Laboratory investigation for patients with suspected
infection with influenza A/H7N9: PHLN recommendations for laboratories
(Refer to downloads).
What are the recommended isolation and PPE recommendations for patients
While further information is accumulating, current recommendations are
for airborne transmission precautions for suspected, probable or confirmed
cases. These recommendations on isolation and PPE for suspected,
probable and confirmed cases take a deliberately cautious approach by
recommending measures that aim to control the transmission of pathogens
that can be spread by the airborne route. These measures are detailed
in NHMRC: Australian Guidelines for the Prevention and Control
of Infection in Healthcare – 2010 (particularly section
B2.4). In summary, transmission-based precautions for suspected,
probable and confirmed cases should include:
- Placement of cases in a negative pressure room if available, or in
a single room from which the air does not circulate to other areas
- Airborne transmission precautions, including routine use of a P2
respirator, disposable gown, gloves, and eye protection when entering a
patient care area
- Standard and contact precautions, including close attention to hand
- If a single or negative pressure room is not available (eg in
primary care settings), or if transfer of the confirmed or probable
case outside the negative pressure room is necessary, asking the
patient to wear a surgical face mask, if tolerated, while they are
being transferred and to follow respiratory hygiene and cough
- Triage areas should have signs asking that patients with severe
respiratory tract infections with a recent history of travel to China
should make themselves known so that appropriate arrangements can be
Suspected case (under investigation)*
- A person with an acute febrile respiratory infection with
clinical, radiological, or histopathological evidence of
pulmonary parenchymal disease (e.g. pneumonia, pneumonitis or
Acute Respiratory Distress Syndrome (ARDS))
AND With one or more of the following
exposures during the 7 days prior to the onset of symptoms:
- Travel to a country where
human cases of H7N9 influenza have recently been
reported, especially if there was recent direct or
close contact with animals (e.g. wild birds, poultry or
- Close contact with a
- A person fitting the definition of a Suspected Case but
with no possibility of laboratory confirmation for H7N9
influenza, either because the patient or samples are not
available for testing AND
- Not already explained by any other infection or aetiology,
including all clinically indicated tests for community acquired
pneumonia according to local management guidelines.
- A person with laboratory confirmation of infection with
H7N9 influenza at a WHO National Influenza Centre.
* Although most of the cases to date have
presented with a severe acute respiratory illness, mild cases have been
reported. If doctors are concerned about patients presenting with milder
illness, they should discuss this with the local public health authorities.
† Currently, China (excluding Hong Kong) is
the only country that has recently reported human cases of H7N9 influenza.
‡ Close contacts include:
- Any person who provided care for the patient or who had other
similarly close physical contact while not wearing appropriate PPE in
the 7 days before symptom onset; this includes health care workers or
- Any person who stayed in the same household as a probable or
confirmed case while the case was symptomatic.
Advice for contacts of cases
Contacts of cases should be directed
to the Communicable Disease Prevention & Control Section of the
Department of Health (Ph. 1300 651 160) for advice. <
Advice for travellers to China
At this time, it is advisable that
travellers to China keep away from sick and dead poultry and livestock and
avoid visiting live animal markets.<
Advice for returned travellers
At this time, if returned travellers
meet the exposure criteria for the case definition but have a less severe
respiratory illness, advice regarding further management should be sought
from the Communicable Disease Prevention & Control Section of the
Department of Health (Ph. 1300 651 160).<
Other useful links
Food and Agriculture Organization of the United Nations (FAO)
Who do I contact if I have a suspected case?
Call the Victorian Department of Health, Communicable Disease Prevention
and Control Section on 1300 651 160.
For advice on any updates to this document please also contact the
Dr Rosemary Lester
Chief Health Officer
Authorised by the Victorian Government, Melbourne.