Arly,
I've always felt that by the time a mother becomes aware that she is
coming down with an illness, the baby has already been exposed to that
disease anyway.  The mother is also already producing antibodies to
whatever is making her sick, so by continuing to breastfeed, the baby is
being given specific antibodies to whatever they are trying to fight
off. I would guess that withholding the breastmilk would be more risky.
Kris Rogers RN,BSN,IBCLC
Crystal Lake, Il