Two died in neighbouring Rattanakiri province, including one person who was trying to escape flooding when the surge swept him into a river and he drowned, authorities said.
Authorities were searching for more victims and sending food, medical supplies and plastic sheeting for temporary tents to storm-hit areas.
Death toll rises
In Vietnam Ketsana left a trail of destruction across the country's central region, with the death toll rising to 38 on Wednesday.
The bodies of two people were recovered from their homes after being buried by a landslide, bringing the toll in Quang Nam to seven, Nguyen Hoai Phuong, a provincial disaster official, said.
Parts of the province were still isolated by flood waters and its main road remained partially submerged.
In Thua Thien Hue province, one more death was reported, bringing the toll there to four.
Buried in landslide
Elsewhere, in the Central Highland region, 30 deaths were reported in six other provinces, including 13 deaths in Kon Tum, the government said in a statement.
The deaths include five members of a family whose house was buried in a landslide.
The typhoon also left 10 people missing, destroyed or damaged nearly 170,000 homes and damaged crops and irrigation systems in the region.
Flooding from the typhoon killed 246 people in the Philippines, inundating the homes of nearly 2.3 million people over the weekend.
The typhoon was downgraded to a tropical storm on Wednesday after crossing into Laos, the national weather forecast center said.