Animal health officials in Vietnam say they have detected the H5N1 bird flu virus on a small duck farm, this second case within a month, has sparked fears of a possible resurgence of the H5N1 virus in the country.

This comes as a disappointment as Vietnam has been free of human bird flu cases so far this year and has had considerable success in the past in dealing and eradicating the deadly virus.

The discovery was made in one duck in the southern Mekong Delta province of Ben Tre, and follows recent reports of new outbreaks of the H5N1 virus in Vietnam’s neighbours Laos, China and Thailand.

The virus appeared among eight samples taken from a farm of 45 ducks in Thanh Phu town.

According to Vietnamese authorities in the area all the ducks on the farm were immediately culled on Saturday and ducks in 14 nearby farms were also tested for the virus, but to date the results were all negative.

The source of the virus is as yet unknown and no one in nearby villages has become sick from the infected birds.

It seems the that the ducks were raised in an enclosed farm and had not been let out in the open for some time.

The farm and surrounding areas have been disinfected.

Another H5 subtype of the virus resurfaced in Vietnam in recent weeks, mainly in ducks and wild storks, but there have been no human infections of H5N1 since last December.

The Vietnamese authorities are aware that although the virus remains essentially an animal disease, it can return at any time and any mutation could trigger a pandemic.

Earlier this month Indonesia overtook Vietnam as the country with the most human deaths from avian flu; Indonesia has now suffered 46 reported deaths compared to Vietnam’s 42 since the virus re-emerged in late 2003.

The government had imposed a ban on hatching and raising water fowl, which can carry the virus without showing symptoms but the ban was said to be largely ignored by farmers.

There are estimated to be as many as 50 million to 70 million water fowl in the country.

Earlier this month, Prime Minister Nguyen Tan Dung put the nation on high alert after new outbreaks were reported in neighboring countries and urged local governments to tighten control along the land borders to prevent poultry from being smuggled into the country.

The country had been commended for controlling the spread of the virus through strong political commitment and a mass vaccination campaign.

According to the World Health Organisation, worldwide, 141 people have been killed, and millions of birds have either died from the virus or been culled because of it.