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RESUME

ABSTRACT

The emergence of the influenza H1N1 pandemic virus with a porcine origin in 2009 shows the importance of swine influenza virus surveillance programs. The situation in Vietnam is conducive to the reassortment of human, swine and avian virus strains in pigs because of the large number of multi-species small farms with low biosafety level. To study the pig-poultry interspecies transmission, two surveys were carried out:
- a transverse survey with random sampling to estimate the swine influenza viroprevalence and to identify risk factors,
- a survey based on surveillance of porcine respiratory diseases to isolate the virus.

In total, 604 pigs and 475 poultry were sampled. Porcine swabs were tested with a rapid influenza antigen detection test, then with RRT-PCR, and avian swabs by RRT-PCR only. All tests were negative. In total, 93 farms were investigated, of which 28 with respiratory symptoms in pigs. The maximum possible viroprevalence estimated for the sample, with WinEpiscope ®, is 4 % for transverse survey farms with a level of confidence of 95 %, and 10 % in farms with symptoms. The importance of porcine respiratory diseases in farms was determined through the use of questionnaire analysis. This study enables the identification of the limits of transverse and surveillance surveys for swine influenza viruses. Suggestions were formulated concerning protocols for porcine respiratory disease surveillance, slaughterhouse surveys, and targeted kinetic studies.

KEY WORDS : influenza virus, pig, poultry, Vietnam, surveillance, prevalence, risk factor, interspecies transmission.