oozing body odor

Please, who knows how i can talk to a colleague of mine about his body odor? This kinda chat is one of the most awkward chat to have.
How do i tell him his hygiene isn't up to snuff?.
The odor is sickening and i think it's so unfair for someone to make another sick with their body odor.
Maybe he doesn't know about it but he needs to know and find solution asap.....!!!