HANOI, Nov 7 (Reuters) - Bird flu has killed 590 ducks in a northern Vietnam province, the fifth to have reported outbreaks among poultry within about a month, the government said on Wednesday.

The two-month-old ducks started dying on Monday at a farm in Ha Nam province. Tests confirmed on Wednesday the presence of the H5N1 bird flu virus, the Animal Health Department said in its daily report.

Further tests also found the H5N1 virus in samples taken from two dead chickens dumped in a river in Ha Nam province, 60 km (37 miles) south of Hanoi, the report said.

The case in Ha Nam brought to five the number of provinces that have confirmed bird flu in poultry since early October. Three of the provinces are in the north, one is in the southern Mekong delta, while the fifth is in the central province of Quang Tri.

Floods that affected Quang Tri in the past two weeks could help spread the virus to nearby areas, an Agriculture Ministry official said.

No human infections have been reported in Vietnam since the virus killed a teenager in early August, one of four deaths among seven Vietnamese known to have been infected this year. Since 2003, bird flu has killed 46 people in Vietnam.

Globally, the H5N1 virus has killed 205 people out of 334 known cases, with most of the deaths in Indonesia, Vietnam, Thailand and Egypt, the World Health Organisation figures show. (Reporting by Ho Binh Minh, editing by David Fogarty)