Surveillance of avian influenza A(H7N9) virus infection in humans and detection of the first imported human

Surveillance of avian influenza A(H7N9) virus infection in humans and detection of the first imported human On 3 April 2013, suspected and confirmed cases of influenza A(H7N9) virus infection became notifiable in the primary care sector in Taiwan, and detection of the virus became part of the surveillance of severe community-acquired pneumonia. On 24 April, the first imported case, reported through both surveillance systems, was confirmed in a man returning from China by sequencing from endotracheal aspirates after two negative throat swabs. Three of 139 contacts were ill and tested influenza A(H7N9)-negative. The Taiwan Centers for Disease Control (TCDC) listed avian influenza A(H7N9) virus infection in humans as a nationally notifiable disease on 3 April 2013 [1], after the Chinese authorities had on 31 March 2013 announced the identification of two male influenza cases in Shanghai and one female case in Anhui with severe respiratory disease caused by an avian influenza A(H7N9) virus that had not previously been detected in humans or animals [2]. The viruses had genetic markers known to be associated with adaptation to mammalian hosts and respiratory transmission of avian influenza viruses, raising concerns about their pandemic potential [2]. The probability of introduction of this virus into Taiwan is considered high because of geographic proximity and more than 90,000 personal or business travels from Shanghai and Anhui to Taiwan per month. This report summarises Taiwan's surveillance for avian influenza A(H7N9) virus infection in humans in the period from 3 April to 10 May 2013. The National Influenza Surveillance System (NISS) in Taiwan consists of virological surveillance by senti-nel primary care physicians, syndromic surveillance of influenza-like illness in emergency and outpatient departments, and surveillance of influenza with complications reported through the National Notifiable Disease Surveillance System. These surveillance activities have been described [3,4]. On 3 April 2013, the TCDC added human infection with avian influenza A(H7N9) virus into the National Notifiable Disease Surveillance System to detect suspected and confirmed cases in the primary care sector. Before 3 April 2013, specimens positive for untypeable influenza A submitted through NISS were routinely tested for influenza A(H5) by realtime RT-PCR. Since 3 April 2013, such specimens have in addition been routinely tested by RT-PCR for influenza A(H7). The TCDC has also conducted surveillance of severe community-acquired pneumonia (CAP) of unknown aetiology since 2010. We focused on these two surveillance activities in this report. The maximal incubation period of influenza A(H7N9) was …