Human infection with avian influenza A(H7N9) virus – China
On 10 May 2016, the National Health and Family Planning Commission (NHFPC) of China notified WHO of 11 additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus, including 4 deaths.
Onset dates range from 23 March to 21 April. The cases range in age from 23 to 69 years, with a median age of 52 years. Of these 11 cases, 7 (64%) are male. The majority (10 cases, 91%) reported exposure to live poultry, slaughtered poultry or live poultry markets. One (1) case has a history of selling pork in a market.
Cases were reported from 5 provinces and municipalities: Jiangsu (6), Jiangxi (2), Anhui (1), Shandong (1) and Zhejiang (1).
One cluster was reported. It includes:
- A 23-year-old male from Jiangxi Province who developed symptoms on 1 April and was admitted to hospital on 8 April. He purchased poultry at a live poultry market. The patient is currently in critical condition.
- A 43-year-old female case from Jiangxi Province who developed symptoms on 5 April and was admitted to hospital on 15 April. She was exposed to slaughtered poultry at a market and was also exposed to the 23-year-old male. She is currently in critical condition.
Human to human transmission between the two patients cannot be ruled out, even though they both have a history of poultry exposure. Further information is awaited.
Public health response
The Chinese Government has taken the following surveillance and control measures:
- strengthening outbreak surveillance and situation analysis;
- reinforcing all efforts on medical treatment; and
- conducting risk communication with the public and dissemination of information.
WHO risk assessment
Most human cases are exposed to the A(H7N9) virus through contact with infected poultry or contaminated environments, including live poultry markets. Since the virus continues to be detected in animals and environments, further human cases can be expected. Although small clusters of human cases with influenza A(H7N9) viruses have been reported including those involving healthcare workers, current epidemiological and virological evidence suggests that this virus has not acquired the ability of sustained transmission among humans. Therefore further community level spread is considered unlikely.
Human infections with the A(H7N9) virus are unusual and need to be monitored closely in order to identify changes in the virus and/or its transmission behaviour to humans as it may have a serious public health impact.
WHO advises that travellers to countries with known outbreaks of avian influenza should avoid poultry farms, contact with animals in live bird markets, entering areas where poultry may be slaughtered, or contact with any surfaces that appear to be contaminated with faeces from poultry or other animals. Travellers should also wash their hands often with soap and water. Travellers should follow good food safety and good food hygiene practices.
WHO does not advise special screening at points of entry with regard to this event, nor does it currently recommend any travel or trade restrictions. As always, a diagnosis of infection with an avian influenza virus should be considered in individuals who develop severe acute respiratory symptoms while travelling or soon after returning from an area where avian influenza is a concern.
WHO encourages countries to continue strengthening influenza surveillance, including surveillance for severe acute respiratory infections (SARI) and to carefully review any unusual patterns, in order to ensure reporting of human infections under the IHR (2005), and continue national health preparedness actions.