ECDC Rapid Risk Assessment On H7N9

 

# 7064

 

The ECDC has published a rapid assessment on the emergence of the H7N9 virus in China.  Excerpts follow, but click the link for the entire PDF.

 

Severe respiratory disease Associated with a novel influenza A virus, A(H7N9) – China

3 April 2013

 
On 31 March, the Chinese authorities announced the identification of a novel influenza A virus, A(H7N9), in three seriously ill people in two provinces. Two male cases in Shanghai without any epidemiological link aged 87 and 27 years old became ill with respiratory infections in mid to late February and both have died.

In Anhui Province, a 35-year-old woman became ill on 9 March and is now in critical condition. The three cases presented with acute high fever onset, cough and respiratory tract infection symptoms. After five to seven days, the patients developed severe pneumonia, progressing rapidly into acute respiratory distress syndrome.

The influenza A viruses from the three cases were non-subtypeable and were sent to the WHO Influenza Collaborating Centre at the Chinese Center for Disease Control and Prevention (CDC). They were sequenced and found to be almost identical. China CDC posted an announcement on its website (31 March) and lodged the genetic information on the publicly accessible GISAID website. It identified genes from both A(H7N9) and A(H9N2) viruses, thus indicating a novel reassortant avian influenza A virus. No similar viruses have been seen before and they differ genetically from A(H7) and A(H9) viruses that have been detected in Europe and elsewhere worldwide. This is the first time that human infection with influenza A(H7N9) virus has been identified. It is also the first time that human infection with a low pathogenic avian influenza A virus has been associated with a fatal outcome.

The Chinese CDC reports that most close contacts of the confirmed cases from Shanghai and Anhui have not shown similar symptoms so far. However, there are reports of a small family cluster of severe disease around the first case. There are no links between the three cases and no obvious association with bird die-offs (which may not have any relevance, since this is a low-pathogenic avian influenza virus and will not cause any poultry die-offs). Chinese authorities have notified the event to WHO under the International Health Regulations (IHR) for assessment. Local investigations are underway in China and it is too early to anticipate the outcome of these as additional patients with severe respiratory disease are under investigation.

Main conclusions and recommendations continued
Threat assessment

Such severe disease involving a novel reassortant influenza virus, in the context of an unknown animal source and mode of transmission is a significant public health event requiring notification under the terms of the International Health Regulations (IHR). As such it was notified through the IHR system by the Chinese authorities. The risk of disease spread to Europe is considered low at this stage though  individual cases coming from China cannot be ruled out.

Recommendations for the EU/EEA
There is no need for any change in case finding strategy that was developed in relation to human infections with highly pathogenic avian influenza A (H5N1) virus. This new event stresses the importance of considering the possibility of zoonotic influenza due to novel influenza A viruses in persons presenting with severe acute
respiratory disease who have recently been in countries where there are animal influenza A viruses circulating, and have recently caused severe respiratory disease in humans which includes China.

It will be important that EU/EEA countries:

• Remind clinicians and laboratory specialists to consider the possibility of human infection with novel
• influenza A viruses such as A(H7N9) and A(H5N1) in persons presenting with severe acute respiratory
  disease who have, in the last ten days, been in China and other countries where there are have been animal influenza A viruses circulating known to have recently caused severe respiratory disease in humans.
• Clinicians should also be reminded of standard guidance for infection control and contact tracing around such cases.
• Similarly, standard guidance should be applied for vigorously investigating clusters of severe respiratory infections and such infections in health care workers who have been caring for patients with severe acute respiratory disease.
• Particular emphasis should be put upon laboratories rapidly referring non sub-typeable influenza A viruses to the WHO Collaborating Centre for Reference and Research on Influenza in London.
• Data from animal surveillance should be examined to ensure that it is known whether any such viruses are present in European animals and birds.
• Although it needs to be noted that as these are low pathogenic avian influenza viruses and they will not be subject to statutory surveillance.
• Patients under investigation for suspected infection with avian influenza A viruses such as H7N9 or H5N1 may need to be notified to national authorities but do not need to be reported to ECDC before confirmation.
• Any confirmed case being diagnosed in the EU/EEA area should be reported to national authorities, through the Early Warning and Response System (EWRS) and to WHO under the International Health Regulations (2005). Reporting through EWRS qualifies as IHR notification and avoids double reporting.