Please do not confuse "mental illness" with the "true" belief some have that "prayer and god heals all human suffering.
Apples and oranges........
The parents did not take the child to the doctor at three to receive "medical attention", they took her to get vaccinated.
I do not defend these parents, not in the least, but if you put them on trial, you put their religion on trial. There are issues about a parents right, a states right, the interest of the state, religion, and the document of the founding fathers.
Can anyone look up the state law and if spirtual healing is a valid defense.
The defense will be "that they acted within their faith, their faith states......that they did not allow their child to die, that they did quite the opposite, they "prayed" for her recovery, that they did not know that she was near death or that she would die. That they put their "faith" in God to heal their child, that it was God's will that she died and that no "man or medical person" can interfere with the "plan of God".
But that does not mean that they will not be convicted.........