Status:
Resolved
Health alert:
140002
Date Issued:
05 Feb 2014 (Update to 9 April circular)
Issued by:
Dr Rosemary Lester, Chief Health Officer, Victoria
Issued to:
Clinicians and Laboratories

Key messages

  • As of 28 January 2014, 238 cases of avian influenza A (H7N9), including 55 deaths, have been reported in China (including Hong Kong) and Taiwan.
  • During the latter part of January and the month of February the number of incoming passengers to Australia from China rises substantially.
  • Patients with pneumonia with a history of travel to China within seven days of illness onset, or contact with known confirmed or probable cases, the following is recommended:
    • Place the patient in a single room with negative pressure air-handling, or a single room from which the air does not circulate to other areas, and implement standard and transmission-based precautions (contact and airborne), including the use of personal protective equipment (PPE).
    • Investigate and manage the patient as for community acquired pneumonia. Appropriate specimens should also be collected for influenza PCR testing.
    • Arrange testing of any suspected or probable cases and contact the Department of Health, Communicable Disease Prevention and Control Section on 1300 651 160 to arrange testing.

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 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 OutbreakNews and Influenza at the Human-Animal Interface.

  • A total of 238 cases have been reported including 55 deaths. To date cases have been reported from 13 provinces of China (Shanghai, Anhui, Jiangsu, Zhejiang, Fujian, Beijing, Guangdong, Henan, Shandong, Hebei, Hunan, Guizhou and Jaingxi), Hong Kong and Taiwan.
  • 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.

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 new virus?

The number of cases identified in China increasing, but still relatively 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 pneumonia and history of travel to, or residence in China within the previous 7 days.
  • Individuals with pneumonia and history of contact with those in point 1 above.
  • Health care workers with 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. Please notify the Communicable Disease Prevention and Control Section on 1300 651 160 when considering testing.
  • 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 available.
  • Gloves, gown, P2 mask 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.

What are the recommended isolation and PPE recommendations for patients in hospital?

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 Controlof Infection in Healthcare 2010 (particularly section B2.4).

In summary, transmission-based precautions for 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 hygiene.
  • 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 etiquette.
  • 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 made.

Case definitions

1. 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 pigs). Close contact with a laboratory-confirmed case.

2. Probable Case

  • 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.

3. Confirmed Case

  • 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) and Taiwan are the only countries that have 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 family members.
  • 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 and Control Section of the Department of Health (Ph. 1300 651 160).