It struck me that there is no mention of any sickness in Christ himself and his apostles. It is amazing that Christ healed countless people, and, apart from mention of fatigue and thirst, no disease or infirmity afflicted he or his closest disciples. Unless I am mistaken?
Peter's mother-in-law was sick with a fever (Luke 4:38-40.)
Yes, Jesus healed her, but she did get sick in the the first place, so she wasn't automatically protected from all infirmity. (I know a mother-in-law isn't the same as being one of his disciples, but this was a close relative of a disciple.)
We don't know if any in his circle got sick, or if Jesus always healed them -- the Bible just doesn't tell us.
One thing we do know is that God did not always save those closest to Him.
James was "killed by the sword," (Acts 12:22,) and Peter, though once rescued by an angel (!!!) from prison, was also eventually martyred.
Tradition has it that he was crucified, but asked that his cross be place upside-down because he said he was not good enough to be put to death in the same manner as his Lord.
Even the most amazing of miracles doesn't mean a person will be spared even worse things.