Raised temps and aquarium salt should do it BUT be sure your frog and fish can handle the temps as not all will go through it.
Also, salt can be bad for some fish (frog too i guess)
Read your fish and frog profile and take according mesures.
If temp and salt is not a solution, then med is the way to go.
Ick or ich is not a disease in any way so it is not contagious by mean..
Its a little creature that live on your fish or in them and feed on them.
They will multiply and then, other fish might or might not get it....
Treatment should lastfor at least 10days depending on temp so you can get rid of it when it is vulnerable....
It is relatively easy to get rid of.
Read on it in the disease forum...
Good luck.