I think that they were infected by indras chakra.
Itachi for obvious reasons, he was born with Sasuke eyes what not.
And Kimmaru because of what juugo says, he is his reincarnation.
I think I was madaras fault for being stubborn and not dieing, Indras chakra needed to move on but couldn't because Madara was holding on to it. It tried to go into Itachi, then kimimaru , but failed, causing them to get infected.
I highly doubt the illnesses were physical...
Itachi for obvious reasons, he was born with Sasuke eyes what not.
And Kimmaru because of what juugo says, he is his reincarnation.
I think I was madaras fault for being stubborn and not dieing, Indras chakra needed to move on but couldn't because Madara was holding on to it. It tried to go into Itachi, then kimimaru , but failed, causing them to get infected.
I highly doubt the illnesses were physical...