Evidence for freedom from swine influenza in a remote area of Northern Vietnam.

Swine influenza is responsible for one of the most prevalent disease affecting the swine industry worldwide. Epidemiological surveys rarely focus on remote areas, because traditional farming systems characterized by locally consumed production and low pig densities are considered as having little influence on the emergence, re-emergence, persistence or spread of swine influenza viruses. In addition, routine disease investigations in remote areas are often neglected due to logistic and economical constraints. A bank of swine sera collected in 2005 in the ethnic minorities households of Ha Giang province (Northern Vietnam) located adjacent to the Chinese border was analyzed to estimate the seroprevalence of swine influenza (SI) and to identify potential risk factors for infection. The results suggest that this specific agro-ecological system is free from SI and is not favourable to SI spread either through pig-to-pig transmission, or through poultry-to-pig transmission.