WHO risk assessment
As seen in previous years, the number of weekly reported cases of infection with avian influenza A(H7N9) virus has decreased over the summer months. However, the number of human infections and the geographical distribution in the fifth epidemic wave (i.e. onset since 1 October 2016) has been greater than earlier waves. This suggests that the virus has spread, and emphasizes that further intensive surveillance and control measures in both the human and animal health sectors remain crucial.Most human case-patients have been exposed to avian influenza 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, and live poultry vending continues, further human cases can be expected. Additional sporadic human cases of avian influenza A(H7N9) are also expected in provinces in China that have not yet reported human cases. Similarly, sporadic human cases of avian influenza A(H7N9) detected in countries bordering China would not be unexpected. Although small clusters of cases of human infection with avian influenza A(H7N9) virus have been reported, including those involving patients in the same ward, current epidemiological and virological evidence suggests that this virus has not acquired the capacity for sustained transmission among humans. Therefore the likelihood of further community level spread is considered low.
Close analysis of the epidemiological situation and further characterization of the most recent viruses are critical to assess associated risk and to adjust risk management measures in a timely manner.
WHO advice
WHO advises that travellers to countries with known outbreaks of avian influenza should, if possible avoid poultry farms, contact with animals in live poultry 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, and follow good food safety and food hygiene practices.WHO does not advise special screening at points of entry, nor does it currently recommend any travel or trade restrictions, with regard to this event. As always, a diagnosis of infection with an avian influenza virus should be considered in individuals who develop severe acute respiratory symptoms while travelling in, 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 influenza-like illness (ILI) and to carefully review any unusual patterns; ensure reporting of human infections under the IHR 2005; and continue national health preparedness actions.
