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LinkTADs Webinar on influenza A(H7N9) epidemiology and surveillance in China


25 March 2016 - In the framework of the LinkTADs project, with the aim to facilitate research collaboration and increase coordination between the EU and China’s epidemiology networks, a webinar titled Epidemiology and Surveillance of Influenza A(H7N9) was held on 20 March 2016 in English, using a bilingual presentation (English-Chinese). Over 30 participants registered for the webinar, including professionals from the China Animal Disease Control Centre (CADC) and the China Animal Health and Epidemiology Center (CAHEC), China Field Epidemiology Training Program for Veterinarian (China FETPV) trainers and trainees from national and provincial veterinary agencies, and participants from veterinary colleges and research institutes worldwide as well as FAO Emergency Centre for Transboundary Animal Diseases (ECTAD) country teams in the region.

The 45 minute presentation was given by FAO’s Global Surveillance Coordinator, Sophie von Dobschuetz, who first set the scene by providing the background and current epidemiological knowledge of influenza A(H7N9), which emerged in China as a zoonotic virus in March 2013. As of 15 March 2016, a total of 751 human cases had been reported, of which 294 had a fatal outcome (39 percent case fatality rate). Most cases reported a history of direct or indirect exposure to live domestic poultry at live bird markets (LBMs). Through active surveillance, the H7N9 virus was detected in live birds and the environment of LBMs and, to a lesser extent, on farms. Dr von Dobschuetz then moved on to explain the basics of risk-based surveillance and reviewed risk factors pertinent to the H7N9 virus. A very important characteristic is that infected birds shed virus without showing any clinical signs. This “silent” infection increases the likelihood of undetected virus spread, and consequently of human exposure. Therefore, passive, event-based surveillance cannot be applied for the early detection of H7N9 in poultry populations. Instead, surveillance needs to follow a risk-based approach for early detection, with active sampling and virological testing, targeting those geographic areas, markets and production systems at highest risk of virus introduction.

The presentation concluded with the importance of surveillance activities being designed around clear objectives and that surveillance has to trigger action, therefore results need to be produced, shared, analysed and followed up in a timely fashion. An open question and answer session at the end benefited from very active participation. Of particular value was additional information provided by Chinese participants on poultry value chains and the design of the national surveillance system. The question why highly pathogenic avian influenza viruses of the H5 subtype spread quickly in the region (and beyond), while circulation of H7N9 still seems to be confined to China was discussed in detail. In this regard, colleagues from CAHEC mentioned the local importance and consumer preference for chickens of the yellow-feathered type, the species mainly implicated in H7N9 epidemiology and spread within China. Exclusive local demand for these birds and associated higher prices may be the reason why the virus has had less opportunity to spread beyond borders.

The webinar presentation can be viewed here.

 

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© FAO/Ryan Aguanno

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