You Do Need power plug adapter while traveling from Madagascar to Congo.

Here is Why You Need An Adapter

The outlet and plug type used in Congo are C, D and E and in Madagascar are C and E. This is how they look like.

Madagascar

In Madagascar, outlets of type C and E are in use.

Type C

Type E

Congo

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

Type C

Type D

Type E