Flutrop CIRAD Avian Influenza

The Highly Pathogenic Avian Influenza H5N1 epidemic started in Vietnam in late 2003 and resulted in more than 50 million poultry culled as well as 100 human cases (46 fatal). In 2005, the Government decided to apply a mass vaccination campaign to limit virus circulation and to reduce the threat to human health. Then, neither outbreak in poultry nor in humans were notified for about one year. Late 2006 and in 2007, both poultry and human cases were reported again.

With a majority of poultry vaccinated in the higher risk areas, the clinical expression of H5N1 inevitably changed and as a result the surveillance approach needs to be adapted. Within a FAO project funded by the Japanese Government, a model is tested in four pilot provinces to strengthen the surveillance of H5N1 infection among backyard and commercial poultry. This model was designed to increase the detection and the notification of suspect poultry health events that could be the highly pathogenic avian influenza.

The first step was to stimulate the passive surveillance system using different activities including targeted awareness campaign and training programs and to improve the data standardisation and management at different levels. One of the purposes of this awareness campaign was to disseminate a very sensitive case definition for HPAI suspicions.

The second step was to develop an active surveillance programme. One component of this program was to test a disease-free certification for vaccinated, semi-commercial broiler farms. The second component was a risk-based surveillance programme, named Community Animal Disease Surveillance, CADS, using participatory approach for data collection. This CADS activity was designed to increase the chance of detecting outbreaks in communes selected according to history of outbreak and risk factors for disease transmission (semi-commercial farms density, total poultry density, road density, presence of live birds markets, and presence of wetlands).
For each of those activities performance indicators were developed to monitor the global implementation but also to assess improvements of some critical points related to the delays in reporting, the application of proper outbreak investigation…

The detailed methodology of this surveillance model, preliminary results and identified constraints are presented.

Key words : HPAI, vaccination, surveillance, participatory disease surveillance, Vietnam