Geographic tongue is not a virus and it isn't contagious.  Some people
are born with it.  It is due to the thickening of the surface cells
on the tongue.  The raised areas look white - like a road map.  That's
why it's called "geographic."  It is often misdiagnosed as thrush.
My brother has it and he claims that it doesn't cause him any discomfort
unless he eats acidic fruits.  Pineapple and kiwi are the worst.
To my knowledge, it shouldn't cause any breastfeeding difficulties.
Just keep the baby away from acidic foods in the future.

Susan Nachman-Srebrnik, LC
Ranana, Israel