ducks in Nam Dinh Province have tested positive for the H5N1 virus, according to Hoang Van Nam, chief of the Department of Animal Health Wednesday.
Nam made his announcement a couple of days after Vietnam reported that it hasn't recorded any avian flu outbreaks, neither in humans nor birds, since July.
The recurrence signals the return of the epidemic season, according to Nam whose department falls under control of the Ministry of Agriculture and Rural Development.
Nam urged outbreak monitors nationwide to remain vigilant and to be prepared to mobilize preventative measures, should the virus spread.
In the meantime, foot-and-mouth disease, a highly contagious and sometimes fatal viral disease hosted by cloven-hoofed animals, has infected cattle populations in seven different provinces, according to Nam.