You Do Need power plug adapter while traveling from Vietnam to Senegal.

Here is Why You Need An Adapter

The outlet and plug type used in Senegal are C, D, E and K and in Vietnam are A, B and C. This is how they look like.

Vietnam

In Vietnam, outlets of type A, B and C are in use.

Type A

Type B

Type C

Senegal

In Senegal, outlets of type C, D, E and K are in use.

Type C

Type D

Type E

Type K