Changing an Existing Order

My question involves a child custody case from the State of: PA
My child was exposed potential deadly disease while in the custody of the non custodial parent. Would I be able to request a modification to the visitation schedule, until at the very least her treatment is completed? Which could be over a year.

You might be able to seek modification on the grounds that treatment must take priority for a while, but unless the child was knowingly, willfully, and actively exposed by the NCP, that part won't be a factor (potential deadly diseases are everywhere).