Avian Influenza A (H7N9) Virus
Human infections with a new avian influenza A (H7N9) virus were first reported in China in March 2013. Most of these infections are believed to result from exposure to infected poultry or contaminated environments, as H7N9 viruses have also been found in poultry in China. While some mild illnesses in human H7N9 cases have been seen, most patients have had severe respiratory illness, with about one-third resulting in death. No evidence of sustained person-to-person spread of H7N9 has been found, though some evidence points to limited person-to-person spread in rare circumstances. No cases of H7N9 outside of China have been reported. The new H7N9 virus has not been detected in people or birds in the United States.
It’s likely that sporadic cases of H7N9 associated with poultry exposure will continue to occur in China. Cases associated with poultry exposure also may be detected in neighboring countries. It’s also possible that H7N9 may be detected in the United States at some point, possibly in a traveler returning from an affected area. Most concerning about this situation is the pandemic potential of this virus. Influenza viruses constantly change and it’s possible that this virus could gain the ability to spread easily and sustainably among people, triggering a global outbreak of disease (pandemic).
On Feb. 3, 2014, the National Health and Family Planning Commission (NHFPC) of China notified the World Health Organization (WHO) of four additional laboratory-confirmed cases of human infection with avian influenza A(H7N9) virus, including one death.
Details of the cases are as follows:
A 27-year-old man from Zhangzhou City, Fujian Province, who became ill on January 21 and admitted to the hospital on January 31. He is currently in critical condition. The patient has a history of exposure to a live poultry market.
A 59-year-old man from Loudi City, Hunan Province, who became ill on January 23 and was admitted to the hospital on January 31. He died on February 3. The patient had a history of exposure to live poultry market.
A 2-year-old female from Zhongshan City, Guangdong Province, who became ill on January 31 and was admitted to the hospital on the same day. She has a mild illness. The patient has a history of exposure to live poultry and a live poultry market.
A 76-year-old woman from Huizhou City, Guangdong Province, who became ill on January 27 and was admitted to the hospital on February 1. She is currently in serious condition. The patient has a history of exposure to live poultry.
So far, there is no evidence of sustained human-to-human transmission.
The Chinese government continues to take the following surveillance and control measures: strengthen surveillance and situation analysis; reinforce case management and treatment; conduct risk communication with the public and release information; strengthen international collaboration and communication; and conduct scientific studies.
While the recent report of avian influenza A(H7N9) virus being detected in live poultry imported from the mainland to Hong Kong SAR, shows the potential for the virus to spread through live poultry, at this time there is no indication that international spread of avian influenza A(H7N9) has occurred through humans or animals.
Further sporadic human cases of A(H7N9) infection are expected in affected and possibly neighbouring areas, especially given expected increases in the trade and transport of poultry associated with the Lunar New Year.
WHO advises that travelers to countries with known outbreaks of avian influenza should avoid poultry farms, or contact with animals in live bird markets, or 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.